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E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 08-07-2011, 07:40 PM
avs4820 avs4820 is offline
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Location: Portland, OR
 
Join Date: Mar 2011
Posts: 11
Mein Auto: 1997 528i Auto
How I fixed the tranny limp mode, error p0720

If you don't like reading that much, just skip to the bottom three paragraphs, cuz that's where the solution is, everything else is just my stupid story... i didn't put pics directly into the post, but i made a lot of links, just click on them to see what i'm talking about..

Good time of day everyone! I'm relatively new to the forum, joined a while ago but so far have been just reading a lot on here...

I'd like to share my story and how I got my p0720 error (output speed sensor circuit) fixed and hope this will help someone, someday!

I have a 1997 528i automatic with 244K miles, still running strong. About 4 days ago i was taking a trip from Oregon to California going on HWY 101. Decided to drive though an unpaved, gravel road that goes through the Redwood National forest to check out some big trees - Howland Hill Rd. On this Google Maps Link part of the road I failed to notice i big a$$ rock and drove the car straight over it at about 10mph. The rock hit the bottom of the car a couple of times as it rolled underneath, not too violently, but could definitely feel it. I stopped the car, shut it off, hit myself in the face a couple of times, came out and looked under to see the damage and if anything was leaking. Couldn't see any real damage, no leaks, but there was a slight dent in the transmission fluid pan.

Ok, got back in the car and started it. Check Engine Light was on, wasn't on before this happened. I started driving and noticed the tranny doesn't shift out of the first gear, i continue to accelerate and at 3000rpm the tranny jerks itself into 3rd (i think) gear and Trans Failsafe Prog comes on. At this point the person I hate the most in the whole world is none other but myself. I stop, looked under the car again, disconnected the battery for a few minutes (why the heck not?), but it doesn't fix the problem. At that time I knew next to nothing about this tranny indicator light or limp mode, other than what i read in the owner's manual right after it happened.

I was way too far away from any BMW dealers or shops, the car could move so I had no choice but to continue driving. Around 800 miles later I make it home, all this time in limp mode. I have owned 2 bmws (both were '97 E39 528i's) and I know that with normal operating condition when you go 80mph the car is at just over 3000rmp, but in limp mode I was at 3000rpm at 70-75mph, so I was going around 60-65 the whole way. Also the car simply couldn't get much above 3000rmp. Going through some of the mountain passes i could barely go 60mph. Later down the road I noticed that I could manually shift it from 3rd to 2nd and back, but no 1st or 4th.

So i got home and started reading the ish out of this forum. Figured out that it was useless to do anything without knowing what code the car gives. BTW, I'm broke as hell and it was a tough decision to go by the OBDII scanner. Got myself the cheapest thing they had at Oreilly's autoparts - Innova 3030 OBDII code reader. Plugged it in, gave me the code P0720 - Output Speed Sensor Circuit. Back to reading...

Idk, maybe it's just me but there is SO MUCH confusion going on on the web about what sensor is called what, where they are located and so on. Looked at tons of diagrams, came to the conclusion that at most OEM diagrams these "speed sensors" actually are called pulse generators. Not even talking about CAM- vs CRANK- shaft position sensors mess.

Anyway, I started by taking off the trans fluid pan in hopes to see if there is any damage. I followed this exact procedure as the trannys are the same E36 Transmission Fluid Change. I couldn't see anything out of the ordinary except that the fluid was BLACK, smelled burned, and everything was covered in a thick layer of sludge. Main reason I was taking the pan off is because on some diagrams and pictures i looked through, there was some sort of a speed sensor installed right in plain view after pan removal, just like the brown two pin connector on the bottom here (NOT where the finger is), and #6 on the diagram here. I know, different car... I obviously didn't see anything like that, my tranny looked like this and there was no such speed sensor there, later i looked through A4S 270R/310R diagrams and there is no speed sensor under the pan.

I cleaned everything, got new filter and gasket (from Autozone), some DexIII/Merc Fluid and put everything back together. I didn't expect just the fluid change alone to fix anything, but i took it for a drive and it still kicked itself into limp mode after 3000rpm but it did it a lot smoother than before. I parked it and did some more reading. Something made me take out the Crankshaft Position Sensor following this procedure. I took it out, looked at it and noticed that there is a tiny crack on the bottom of it, here is a picture of it, there was also some fluid (engine oil?) coming out of it in tiny amounts. I thought that this could be the problem, BTW I am having some cold starting problems which I think could be due to this sensor going bad so I'm going to be replacing it soon. As for now, I put it back in but DID NOT yet connected it. Started the car with difficulty, and in addition to P0720 code, it gave me P0335 code (Crankshaft Position Censor Circuit), connected the sensor, P0335 code disappeared. So that made me think that my P0720 code has nothing to do with the CPS. Back to reading...

IDK what took me so long but during my last reading session i stumbled across a forum post saying something about a pulse generator located on the rear top of the tranny. I then looked closer at the A4S 270R/310R diagram here and the part I'm talking about is #4. Since the diagram is called "A4S 270R/310R output" and part #4 is called a pulse generator (AKA speed sensor), my brain finally put it together: THIS MUST BE THE OUTPUT SPEED SENSOR" my code reader is talking about. So I jack the car up, get under it and start feeling for the sensor. What i found was a damn connector that was just hanging loose, the bump against the rock must've knocked it off the sensor... i plugged it back in, drove the car and everything was perfect. What could have been a 5 second "on-the-spot" fix, turned out to be a 3-day headache and lets just hope that i didn't mess up my tranny more by driving it so far in limp mode...

The moral of the story is i guess, whenever there is a problem check the damn electrical connections first and get yourself the OBDII scanner. Read, read, read the forums, use search and your head, don't go to the stealer unless you absolutely have to.. I went.. they told me straight up without looking at the car that I need a new tranny...

Hopefully this info was somewhat interesting and will be helpful to someone. The end!
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  #2  
Old 08-08-2011, 11:52 AM
microswitch's Avatar
microswitch microswitch is offline
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Location: Los Angeles
 
Join Date: Dec 2009
Posts: 291
Mein Auto: 2006 5251
That is great way of staying with the problem. I'm sure a dealer would have made a bundle on you.
It goes to show a bit of "handyness" with tools and a clear mind, with persistence AND this forum, you can do anything.
Congrat on saving yourself mucho bucks and the pride of having fixed a major problem.
Thank you for sharing
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  #3  
Old 09-08-2011, 10:11 PM
jstancic jstancic is offline
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Location: Kansas City
 
Join Date: Apr 2011
Posts: 8
Mein Auto: 525i
Your story was inspiring. I'm not kidding. My 2001 525i has been out of commission for a year now. Blew the head gasket. Replaced it. Couldn't get it to run right after that. No power at all. I've taken it apart 5 times. Today I adjusted the cams (which I refused to believe was the cause of my problems). One cam sprocket was one tooth off, the other was 3 teeth off. I've learned the hard way with every turn of the wrench on this car. I'm IRS poor so I can't just throw money at it either. I have to budget parts, etc. I'll make my point and sign off. I have searched and read plenty on this forum and have come to this conclusion. There are a ton of folks that are eager to help and very few that can teach you something. You, my friend, have taught me that I need to remember to always consider the basics and to double check myself. I don't have a sensor on my car that tells me to do that. Thanks.
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  #4  
Old 09-23-2011, 05:23 AM
maggy maggy is offline
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Location: bristol ct
 
Join Date: Sep 2011
Posts: 3
Mein Auto: bmw325i
Thumbs up tranny problem

can you please let me know were is located the output speed sensor i work on it all day yesterday and did not find it, i am trying to do the job my self. becouse the mecanic wants 21 hundred dollar. ufff . please thank you.
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  #5  
Old 09-23-2011, 06:12 AM
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doru doru is offline
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Location: Calgary
 
Join Date: Sep 2007
Posts: 4,457
Mein Auto: 2003 530iA
Nice find. This is for a GM tranny I believe.
For my ZF5HP19 tranny (2003 / 530) the speed sensor is inside the slushbox.
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  #6  
Old 09-23-2011, 10:48 AM
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bluebee bluebee is offline
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Location: San Jose, California
 
Join Date: Mar 2008
Posts: 20,420
Mein Auto: 02 BMW 525i M54 auto 130K
For the record, these are some solutions to the limp mode:
- How people resolved transmission "Trans Failsafe Program", aka "Limp Mode" (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15)

I just clicked on a couple, and this one seems to be something similar. Is it?
- HELP! My first E39, and first Transmission Problem

Quote:
OK, there is a switch/selector for the trans that can fail and cause these symptoms.

The part I had a prob with was Part number 6 in this diagram. If there are wires crossed that would explain your condition. On initial startup everything is fine, but after a while it recognizes the prob and goes into safe mode.

http://www.realoem.com/bmw/showparts...20&hg=24&fg=15
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  #7  
Old 09-19-2013, 10:19 PM
emaxon emaxon is offline
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Location: Chicago, IL
 
Join Date: Sep 2013
Posts: 7
Mein Auto: 2002 330cic
Don't drive through water! (Another cautionary P0720 tale)

My first post here.... had to join to chime-in. The original poster and his rock saga was the single most helpful read for solving last night's p0720 (and other wrong gear ratio codes, limp-home) nightmare with my car. A call to Ben Thongsai of B&D Auto, (THE BMW guru of Chicago,) confirmed that water incursion into the electrical connectors on the trans, and even into the selector shaft switch itself are not unheard of. It was raining so damn hard here in Chicago last night I saw no puddle, let alone a half block long lake. 2/3 of the way through, loss of momentum, trans limp-home mode. I gathered from the description of the plug in this thread that you guys have the GM trans. I've got the ZF box, and there are two plugs... one clearly visible at the front lower left, which is just for the selector shaft switch, and another, barely visible, near the left mid rear, concealed by the mount bracket. This morning, I opened up the front connector, shook it out, let it dry for a few hours, greased it with dialectric grease, went for a spin. No joy... same codes, clunky shifting, limp-home as soon as I exceeded 15mph. I finally found some photos of used zf boxes, saw the second connector. Sure enough, many more pins, totally water-logged, thanks in part to a torn boot. Shaking it out, cleaning it with Caig Deoxit, (I favor Wurth Contactol, but am out,) working it in/out a few times, greasing with dialectric did the trick. To be thouough, I removed the selector shaft switch, fearing that may have gotten wet inside, saw that it was riveted together... totally unservicable, so I put it right back, wet or not. After servicing both connectors, clearing codes, which btw was possible with an $8 Elm blietooth ebay adapter and the free version of Torq, the car shifted like the underwater excursion never happened.

Be advised that the hall-effect sensors that give speed signals when slotted wheels, gear teeth, etc fly-by, give a very weak signal... as little as 10-20mV for a slowly-turning wheel from a wheel speed sensor. So, if you've got a lousy connection, thanks to corroded contacts, water incursion, etc, it stands to reason that this info will be the first to go. P0720 signifies a lack of a good signal from the sensor that indicates the speed of the output shaft of the trans... little wonder.

Hopefully the next guy who goes surfing with his slushbox E46/39 etc can save some trouble by heading straight for these not-so-watertight connectors.

Thanks again.

Eric

(2002 330cic, 213k and going strong.)

Thanks again for posting your saga... helped me immensely.

Eric.




Quote:
Originally Posted by avs4820 View Post
If you don't like reading that much, just skip to the bottom three paragraphs, cuz that's where the solution is, everything else is just my stupid story... i didn't put pics directly into the post, but i made a lot of links, just click on them to see what i'm talking about..

Good time of day everyone! I'm relatively new to the forum, joined a while ago but so far have been just reading a lot on here...

I'd like to share my story and how I got my p0720 error (output speed sensor circuit) fixed and hope this will help someone, someday!

I have a 1997 528i automatic with 244K miles, still running strong. About 4 days ago i was taking a trip from Oregon to California going on HWY 101. Decided to drive though an unpaved, gravel road that goes through the Redwood National forest to check out some big trees - Howland Hill Rd. On this Google Maps Link part of the road I failed to notice i big a$$ rock and drove the car straight over it at about 10mph. The rock hit the bottom of the car a couple of times as it rolled underneath, not too violently, but could definitely feel it. I stopped the car, shut it off, hit myself in the face a couple of times, came out and looked under to see the damage and if anything was leaking. Couldn't see any real damage, no leaks, but there was a slight dent in the transmission fluid pan.

Ok, got back in the car and started it. Check Engine Light was on, wasn't on before this happened. I started driving and noticed the tranny doesn't shift out of the first gear, i continue to accelerate and at 3000rpm the tranny jerks itself into 3rd (i think) gear and Trans Failsafe Prog comes on. At this point the person I hate the most in the whole world is none other but myself. I stop, looked under the car again, disconnected the battery for a few minutes (why the heck not?), but it doesn't fix the problem. At that time I knew next to nothing about this tranny indicator light or limp mode, other than what i read in the owner's manual right after it happened.

I was way too far away from any BMW dealers or shops, the car could move so I had no choice but to continue driving. Around 800 miles later I make it home, all this time in limp mode. I have owned 2 bmws (both were '97 E39 528i's) and I know that with normal operating condition when you go 80mph the car is at just over 3000rmp, but in limp mode I was at 3000rpm at 70-75mph, so I was going around 60-65 the whole way. Also the car simply couldn't get much above 3000rmp. Going through some of the mountain passes i could barely go 60mph. Later down the road I noticed that I could manually shift it from 3rd to 2nd and back, but no 1st or 4th.

So i got home and started reading the ish out of this forum. Figured out that it was useless to do anything without knowing what code the car gives. BTW, I'm broke as hell and it was a tough decision to go by the OBDII scanner. Got myself the cheapest thing they had at Oreilly's autoparts - Innova 3030 OBDII code reader. Plugged it in, gave me the code P0720 - Output Speed Sensor Circuit. Back to reading...

Idk, maybe it's just me but there is SO MUCH confusion going on on the web about what sensor is called what, where they are located and so on. Looked at tons of diagrams, came to the conclusion that at most OEM diagrams these "speed sensors" actually are called pulse generators. Not even talking about CAM- vs CRANK- shaft position sensors mess.

Anyway, I started by taking off the trans fluid pan in hopes to see if there is any damage. I followed this exact procedure as the trannys are the same E36 Transmission Fluid Change. I couldn't see anything out of the ordinary except that the fluid was BLACK, smelled burned, and everything was covered in a thick layer of sludge. Main reason I was taking the pan off is because on some diagrams and pictures i looked through, there was some sort of a speed sensor installed right in plain view after pan removal, just like the brown two pin connector on the bottom here (NOT where the finger is), and #6 on the diagram here. I know, different car... I obviously didn't see anything like that, my tranny looked like this and there was no such speed sensor there, later i looked through A4S 270R/310R diagrams and there is no speed sensor under the pan.

I cleaned everything, got new filter and gasket (from Autozone), some DexIII/Merc Fluid and put everything back together. I didn't expect just the fluid change alone to fix anything, but i took it for a drive and it still kicked itself into limp mode after 3000rpm but it did it a lot smoother than before. I parked it and did some more reading. Something made me take out the Crankshaft Position Sensor following this procedure. I took it out, looked at it and noticed that there is a tiny crack on the bottom of it, here is a picture of it, there was also some fluid (engine oil?) coming out of it in tiny amounts. I thought that this could be the problem, BTW I am having some cold starting problems which I think could be due to this sensor going bad so I'm going to be replacing it soon. As for now, I put it back in but DID NOT yet connected it. Started the car with difficulty, and in addition to P0720 code, it gave me P0335 code (Crankshaft Position Censor Circuit), connected the sensor, P0335 code disappeared. So that made me think that my P0720 code has nothing to do with the CPS. Back to reading...

IDK what took me so long but during my last reading session i stumbled across a forum post saying something about a pulse generator located on the rear top of the tranny. I then looked closer at the A4S 270R/310R diagram here and the part I'm talking about is #4. Since the diagram is called "A4S 270R/310R output" and part #4 is called a pulse generator (AKA speed sensor), my brain finally put it together: THIS MUST BE THE OUTPUT SPEED SENSOR" my code reader is talking about. So I jack the car up, get under it and start feeling for the sensor. What i found was a damn connector that was just hanging loose, the bump against the rock must've knocked it off the sensor... i plugged it back in, drove the car and everything was perfect. What could have been a 5 second "on-the-spot" fix, turned out to be a 3-day headache and lets just hope that i didn't mess up my tranny more by driving it so far in limp mode...

The moral of the story is i guess, whenever there is a problem check the damn electrical connections first and get yourself the OBDII scanner. Read, read, read the forums, use search and your head, don't go to the stealer unless you absolutely have to.. I went.. they told me straight up without looking at the car that I need a new tranny...

Hopefully this info was somewhat interesting and will be helpful to someone. The end!
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  #8  
Old 09-20-2013, 04:26 AM
Fudman's Avatar
Fudman Fudman is offline
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Location: Sudbury, MA
 
Join Date: Apr 2007
Posts: 6,157
Mein Auto: '02 530i Sport auto
+1, a wet drive also triggered my TPF and limp mode many years ago. This underlines the fact that many tranny "problems" are in fact, not tranny problems but triggered by a sensor (wet or broken). Look for the easier fix before replacing your tranny.
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  #9  
Old 09-20-2013, 05:12 AM
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shaftdrive shaftdrive is offline
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Location: USA
 
Join Date: Mar 2005
Posts: 583
Mein Auto: 1999 K1200 & 2001 525
When mine went into limp mode, it was because of the alternator.
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  #10  
Old 09-21-2013, 07:57 PM
AllesklarBMW AllesklarBMW is offline
Registered User
Location: Seattle
 
Join Date: Sep 2013
Posts: 83
Mein Auto: 530i
Quote:
Originally Posted by bluebee View Post
For the record, these are some solutions to the limp mode:
- How people resolved transmission "Trans Failsafe Program", aka "Limp Mode" (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15)

I just clicked on a couple, and this one seems to be something similar. Is it?
- HELP! My first E39, and first Transmission Problem



Thanks bluebee. I'll check into this data!
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  #11  
Old 10-27-2013, 04:22 PM
buhddy1 buhddy1 is offline
Registered User
Location: dallas texas
 
Join Date: Oct 2013
Posts: 5
Mein Auto: 2002 330i
Quote:
Originally Posted by avs4820 View Post
If you don't like reading that much, just skip to the bottom three paragraphs, cuz that's where the solution is, everything else is just my stupid story... i didn't put pics directly into the post, but i made a lot of links, just click on them to see what i'm talking about..

Good time of day everyone! I'm relatively new to the forum, joined a while ago but so far have been just reading a lot on here...

I'd like to share my story and how I got my p0720 error (output speed sensor circuit) fixed and hope this will help someone, someday!

I have a 1997 528i automatic with 244K miles, still running strong. About 4 days ago i was taking a trip from Oregon to California going on HWY 101. Decided to drive though an unpaved, gravel road that goes through the Redwood National forest to check out some big trees - Howland Hill Rd. On this Google Maps Link part of the road I failed to notice i big a$$ rock and drove the car straight over it at about 10mph. The rock hit the bottom of the car a couple of times as it rolled underneath, not too violently, but could definitely feel it. I stopped the car, shut it off, hit myself in the face a couple of times, came out and looked under to see the damage and if anything was leaking. Couldn't see any real damage, no leaks, but there was a slight dent in the transmission fluid pan.

Ok, got back in the car and started it. Check Engine Light was on, wasn't on before this happened. I started driving and noticed the tranny doesn't shift out of the first gear, i continue to accelerate and at 3000rpm the tranny jerks itself into 3rd (i think) gear and Trans Failsafe Prog comes on. At this point the person I hate the most in the whole world is none other but myself. I stop, looked under the car again, disconnected the battery for a few minutes (why the heck not?), but it doesn't fix the problem. At that time I knew next to nothing about this tranny indicator light or limp mode, other than what i read in the owner's manual right after it happened.

I was way too far away from any BMW dealers or shops, the car could move so I had no choice but to continue driving. Around 800 miles later I make it home, all this time in limp mode. I have owned 2 bmws (both were '97 E39 528i's) and I know that with normal operating condition when you go 80mph the car is at just over 3000rmp, but in limp mode I was at 3000rpm at 70-75mph, so I was going around 60-65 the whole way. Also the car simply couldn't get much above 3000rmp. Going through some of the mountain passes i could barely go 60mph. Later down the road I noticed that I could manually shift it from 3rd to 2nd and back, but no 1st or 4th.

So i got home and started reading the ish out of this forum. Figured out that it was useless to do anything without knowing what code the car gives. BTW, I'm broke as hell and it was a tough decision to go by the OBDII scanner. Got myself the cheapest thing they had at Oreilly's autoparts - Innova 3030 OBDII code reader. Plugged it in, gave me the code P0720 - Output Speed Sensor Circuit. Back to reading...

Idk, maybe it's just me but there is SO MUCH confusion going on on the web about what sensor is called what, where they are located and so on. Looked at tons of diagrams, came to the conclusion that at most OEM diagrams these "speed sensors" actually are called pulse generators. Not even talking about CAM- vs CRANK- shaft position sensors mess.

Anyway, I started by taking off the trans fluid pan in hopes to see if there is any damage. I followed this exact procedure as the trannys are the same E36 Transmission Fluid Change. I couldn't see anything out of the ordinary except that the fluid was BLACK, smelled burned, and everything was covered in a thick layer of sludge. Main reason I was taking the pan off is because on some diagrams and pictures i looked through, there was some sort of a speed sensor installed right in plain view after pan removal, just like the brown two pin connector on the bottom here (NOT where the finger is), and #6 on the diagram here. I know, different car... I obviously didn't see anything like that, my tranny looked like this and there was no such speed sensor there, later i looked through A4S 270R/310R diagrams and there is no speed sensor under the pan.

I cleaned everything, got new filter and gasket (from Autozone), some DexIII/Merc Fluid and put everything back together. I didn't expect just the fluid change alone to fix anything, but i took it for a drive and it still kicked itself into limp mode after 3000rpm but it did it a lot smoother than before. I parked it and did some more reading. Something made me take out the Crankshaft Position Sensor following this procedure. I took it out, looked at it and noticed that there is a tiny crack on the bottom of it, here is a picture of it, there was also some fluid (engine oil?) coming out of it in tiny amounts. I thought that this could be the problem, BTW I am having some cold starting problems which I think could be due to this sensor going bad so I'm going to be replacing it soon. As for now, I put it back in but DID NOT yet connected it. Started the car with difficulty, and in addition to P0720 code, it gave me P0335 code (Crankshaft Position Censor Circuit), connected the sensor, P0335 code disappeared. So that made me think that my P0720 code has nothing to do with the CPS. Back to reading...

IDK what took me so long but during my last reading session i stumbled across a forum post saying something about a pulse generator located on the rear top of the tranny. I then looked closer at the A4S 270R/310R diagram here and the part I'm talking about is #4. Since the diagram is called "A4S 270R/310R output" and part #4 is called a pulse generator (AKA speed sensor), my brain finally put it together: THIS MUST BE THE OUTPUT SPEED SENSOR" my code reader is talking about. So I jack the car up, get under it and start feeling for the sensor. What i found was a damn connector that was just hanging loose, the bump against the rock must've knocked it off the sensor... i plugged it back in, drove the car and everything was perfect. What could have been a 5 second "on-the-spot" fix, turned out to be a 3-day headache and lets just hope that i didn't mess up my tranny more by driving it so far in limp mode...

The moral of the story is i guess, whenever there is a problem check the damn electrical connections first and get yourself the OBDII scanner. Read, read, read the forums, use search and your head, don't go to the stealer unless you absolutely have to.. I went.. they told me straight up without looking at the car that I need a new tranny...

Hopefully this info was somewhat interesting and will be helpful to someone. The end!
i just went thru high water during rain, got the red cog. tried blowing out water from the one connector i could get to, nothing. no OBD codes, but check engine and red cog are on. i don't have a way to get transmission codes. battery is at 13.9 volts according to OBD. Thinking alternator might have been damaged, or egs needs to be reset. any thoughts? 2002 330i 94K. no problems at all before this.
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  #12  
Old 10-27-2013, 05:09 PM
emaxon emaxon is offline
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Location: Chicago, IL
 
Join Date: Sep 2013
Posts: 7
Mein Auto: 2002 330cic
Even w/o clearing the codes via the ELM bluetooth interface, turning off the car, starting up again started with a clean slate TCM-wise... Until 15mph is exceeded. Every time I exceeded 15mph, the TCM went into limp-home mode again... Until I cleaned the difficult-to-reach connector at the rear of the trans.
You'll need to cram your hand above the rear mount cross-member to reach the second connector, regardless of whether you've got the ZF or GM box. It twists to remove, just like the the easy to reach connector up front. The front connector is only for the selector switch that indicates what gear has been mechanically selected... Cleaning, drying, greasing that one didn't help me. The rear connector carries signals for all of the internal temperature and speed sensors... Some of which are as weak as a 20mV P-P pulse train. You've GOT to clean and dry it out, might as well silicone grease it to prevent a future episode. My 2c. Good luck! Eric.
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  #13  
Old 10-27-2013, 05:20 PM
buhddy1 buhddy1 is offline
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Location: dallas texas
 
Join Date: Oct 2013
Posts: 5
Mein Auto: 2002 330i
Quote:
Originally Posted by Fudman View Post
+1, a wet drive also triggered my TPF and limp mode many years ago. This underlines the fact that many tranny "problems" are in fact, not tranny problems but triggered by a sensor (wet or broken). Look for the easier fix before replacing your tranny.
Do you remember what it took to get it fixed? I have the exact same issue.
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  #14  
Old 10-27-2013, 05:54 PM
buhddy1 buhddy1 is offline
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Location: dallas texas
 
Join Date: Oct 2013
Posts: 5
Mein Auto: 2002 330i
Quote:
Originally Posted by emaxon View Post
Even w/o clearing the codes via the ELM bluetooth interface, turning off the car, starting up again started with a clean slate TCM-wise... Until 15mph is exceeded. Every time I exceeded 15mph, the TCM went into limp-home mode again... Until I cleaned the difficult-to-reach connector at the rear of the trans.
You'll need to cram your hand above the rear mount cross-member to reach the second connector, regardless of whether you've got the ZF or GM box. It twists to remove, just like the the easy to reach connector up front. The front connector is only for the selector switch that indicates what gear has been mechanically selected... Cleaning, drying, greasing that one didn't help me. The rear connector carries signals for all of the internal temperature and speed sensors... Some of which are as weak as a 20mV P-P pulse train. You've GOT to clean and dry it out, might as well silicone grease it to prevent a future episode. My 2c. Good luck! Eric.
Eric,

Thanks for the quick response. I saw that thing, and I cannot get my hand in there, can barely touch it with my finger tips. I also cannot find any diagrams that even acknowledge it's existence, which is very strange. I guess I'll jack it up one more time, now that I'm certain I know what it is. But I have the cog at start up every time. Even after disconnecting the battery, and clearing one code about a water temperature sensor. I'll report back.

David
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  #15  
Old 10-27-2013, 08:30 PM
buhddy1 buhddy1 is offline
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Location: dallas texas
 
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Mein Auto: 2002 330i
went swimming in my 330i

Well, I have dried and cleaned both electrical cables going to the transmission, and no luck, even though quite a bit of water came off both connections once opened up. Even used electrical contact cleaner to make sure no residue was left.

Still get the red cog immediately at startup. Letting it sit right now with battery disconnected, hoping that will somehow let the ecu forget about the previous codes and start fresh. I cannot talk to the egs with my elm 327 and movi pro on my mac. Wish me luck.
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  #16  
Old 10-28-2013, 04:56 AM
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Fudman Fudman is offline
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Location: Sudbury, MA
 
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Mein Auto: '02 530i Sport auto
Quote:
Originally Posted by buhddy1 View Post
Do you remember what it took to get it fixed? I have the exact same issue.
Mine sat at the dealer for 2 days as they tried to figure it out. They finally said to replace the tranny. I said forget it, had them reset the tranny light and took the car back. It was fine ever since (until it got totaled). You need a GT-1 or equivalent scanner to reset tranny codes.
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  #17  
Old 10-28-2013, 09:42 AM
buhddy1 buhddy1 is offline
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Location: dallas texas
 
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Mein Auto: 2002 330i
Getting scanned at a local place with the right equipment now.
Will report. Considering filing insurance claim since it was high water that caused it, but only if it's going to be really high.
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  #18  
Old 10-28-2013, 02:59 PM
EconoBox EconoBox is offline
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Location: LA
 
Join Date: Aug 2011
Posts: 937
Mein Auto: 2001 530i (E39) 120k
OP should have Googled that ODB2 code.
First 2 hits would have told him to look for that sensor.
http://engine-codes.com/p0720.html
http://wiki.answers.com/Q/What_is_th...roblem_is_this
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  #19  
Old 02-17-2014, 11:58 AM
55bmw 55bmw is offline
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Location: knoxville tn
 
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Mein Auto: 1992 525i
I replaced my low band solenoid under the trans filter, fixed my tranny problem, finally :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-)
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  #20  
Old 02-17-2014, 01:46 PM
emaxon emaxon is offline
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Location: Chicago, IL
 
Join Date: Sep 2013
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Mein Auto: 2002 330cic
Don't forget to GREASE the electrical connections.

If you're having trouble with limp-home mode, brought-on by an underwater excursion, it's bound to happen again. Beside cleaning and drying the connections at the trans, don't forget to squeeze some dielectric (silicone) grease in the female side to prevent future woes. (I bought the tiny tube, snipped off the tip leaving a very tiny hole, squeezed it into each female socket until it was full of grease.) Both the rubber boots and corrugated plastic sleeves eventually dry up and crack or crumble, making water incursion into these connectors more likely as our cars age, making the grease even more important.
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  #21  
Old 02-17-2014, 06:15 PM
StRaNgEdAyS StRaNgEdAyS is offline
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Location: Caboolture
 
Join Date: Nov 2012
Posts: 122
Mein Auto: E39 535i
This is an excellent thread!
I'm about to dive into the depths of my transmission, I'm hoping one of these solutions works for me.
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