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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 7 Series / 8 Series > 7 Series - E38 (1995 - 2001)

7 Series - E38 (1995 - 2001)

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  #1  
Old 06-21-2010, 12:42 AM
ngraz617 ngraz617 is offline
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Location: Long Island, New York
 
Join Date: Feb 2010
Posts: 31
Mein Auto: 2011 750I X M sport
2001 740i sport

I can be driving on the highway at 65 and car will out on no where downshift to 3rd and unless I go faster it will not go into 4th or if faster 5th as I slow down the car drops gears all the way down to 1st at close to stop. As I go faster it will shift as if in steptronics and shift at the pre designated shift points at red line as if you didn't do it yourself while in steptronics it would do it on its own. it's hard to get past 3rd because you have to go over 70 I think. so regardless of what I do with shifter it does not respond. if I'm doing 65 and it went to third and I put it in manual it would go up on the numbers to 4th on dash but drop back down to 3rd but the tranny doesn't respond at all that remains in 3rd. It can happen when driving around town. I can just be driving around 35 and it all of the sudden out of no where down shift to 2nd and then I speed up it will go to 3rd max and as I slow down back to 2nd or 1st. when I turn car off it will be fine after say 30 minutes and drive perfect as if the problem doesn't exist and then may drive perfect for weeks and then do it everyday for a week or just basically out of no where. It is just as if you were shifting it manually without shifting and it shifts at the pre determined shift points except slowing down too. so as you go slower in 3rd it will downshift at redline second and then red line 1st which it wont do when car is running normal. If you are in manual and shifting yourself and are in 3rd it does not down shift to first on it's own and also in steptronics you can start off in up to third in manual not when this problem happens you don't control it at all. Again you can move the numbers on dash but it will fall back to whatever number car is in and also tranny does not respond when you change the numbers it never changes from what gear you're in. I assumed this was hot mode. Also I never got faults or codes. I changed EGS and then received some which led me to change ignition switch The latest being simply (voltage supply terminal R faulty KOM) will see if there are any codes tomorrow since it was cleared Friday when I picked up the car after having Water pump and thermostat and pulley and belts and Expansion tank without level sensor, Re code instrument cluster updates were installed but not on the cluster it was on the COM or something but not the cluster itself, I think or part of cluster. I have replaced the radiator, water pump, alternator, Battery, rebuilt transmission including wire harness, ignition switch, EGS, reset car to factory specs by putting battery cables togeher for 10 hours clearing out everything.
Anyone, HELP
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  #2  
Old 06-21-2010, 08:05 PM
ngraz617 ngraz617 is offline
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Location: Long Island, New York
 
Join Date: Feb 2010
Posts: 31
Mein Auto: 2011 750I X M sport
Today I went to the garage that services my car and the same terminal R fault was there but then he programmed the KOM to the car and cleared the codes. He uses Auto Logic which is actually similar to the device the BMW dealers use from what I have read. So we hooked up the Auto Logic to the cars engine compartment and went for a ride. We started with the Engine at 108* C and the Transmission oil at 87* C, as we drove the temperature in the transmission kept rising and after a few miles of city and highway driving the Engine was slowly lowering in temp. and the Transmission was going up steadily and the coolant temp was perfect. At exactly 128* C the transmission went into the mode I described and we continued and went back to the shop and the temp continued to go down on the engine and up on the Tranny fluid. When we got back to the shop the engine was 99* C and the tranny was 136* c and if we kept going it would have kept going up, no doubt, how far? I don't know. We scanned the engine and there were absolutely no faults and since he programmed the KOM earlier that fault is now of no concern to us and no longer present. I don't know the standard temperature operating range of the Transmission Fluid so I don't know if it was hot or not and once I find out that will narrow down what the possibilities are at this time. If it was the interior wire harness as per SIB 24 02 01, I would get a code 34 stored in the TCM which I didn't. Hopefully while my mechanic does some homework I will get some answers from some of you who are somewhat familiar with this issue. Again the Transmission shop claims to have replaced the wire harness #24 00 92 79 00 and I know he did in fact purchase it but I don't know if he did the following.

A) Replace the temp. sensors, there are 2 on this harness because it is unclear if that has to be done and if in fact he did the harness and not the sensors that could be a problem because the sensors may or may not come with the harness but if you were doing the harness I would think you would do the sensors. I believe at least 1 sensor comes with the wire harness, the other sensor if you look at the diagram could be separate.

B) Remove and replace the sensor (s) and exchange them with the ones that exist on the existing wire harness already in the transmission therefore not replacing the wire harness which is in fact the problem due to an "Incorrect crimp of the transmission temperature sensor connector" This is more likely but until it is opened up I wont know. This all happened at the end of the day.

C) It's possible he didn't do the harness at all but like I said it was purchased.



Anything you can tell me based on this information will be greatly appreciated and any repairs or suggestions will be great.

Thanks
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  #3  
Old 07-01-2010, 10:16 PM
ngraz617 ngraz617 is offline
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Location: Long Island, New York
 
Join Date: Feb 2010
Posts: 31
Mein Auto: 2011 750I X M sport
In case in the future someone has a problem like I described I will post what should be done. You have to go to a BMW repair shop that has an Auto Logic Diagnostic machine or similar and run your car and while driving track your ATF temp. While you drive. If your temp. goes up like mine did and you go into hot mode start by checking that your trans has enough ATF and that your voltage regulator and heat exchanger are running right and not clogged as well as the two metal tubes that run back to the trans. if you are running hot and check that your oil pump in the trans is pumping through the tube I would change voltage reg. and heat exchanger. I would then see if you are running cooler. if you are that was most likely the problem but if you are running a little on the hot side still but not hot where the car should go into hot mode then replace the wire harness in trans valve housing and that should be it. SO far I'm running at most 100*c now and have not gone into hot mode and have driven car for hours at a time so it looks like around 126*c + is too hot and can cause problems and changing these parts should cool you down if you don't have another trans problem. If this works you will be fine. if you are going into hot mode and not running hot it's just the wire harness..
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  #4  
Old 07-01-2010, 10:16 PM
ngraz617 ngraz617 is offline
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Location: Long Island, New York
 
Join Date: Feb 2010
Posts: 31
Mein Auto: 2011 750I X M sport
Special thanks to Wiggi for helping me out and everyone else.
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