Help! If I don't fix this, I'm selling this F*ing BMW!!

I am at my wit's end, and am dangerously close to having a heart attack at age 25. Here's the problem:
Car will crank strong but not start. Keeps blowing DME fuse #3 (20amp). Every time I think I have it fixed, the problem returns. I have been working on this for 3 weeks now, and I am not a stranger to cars.

What sensors, etc go to DME fuse #3:
* A/C compressor clutch
* Camshaft position sensors
* Crankshaft position sensor
* DME & Fuel pump relays
* Evaporative system leak diagnostics pump
* Mass air flow sensor
* Secondary air pump
* Electric thermostat

What I have done:

1. Checked all other fuses, all were good.
2. Disconnected sensors that go to that fuse one by one, didn't blow when intake cam position sensor was disconnected. However, this was temporary, and the problem came back
3. Disconnected all sensors on that circuit except the AC clutch (don't know how), and it still kept blowing!
4. Disconnected the fuel pump and it started briefly.
5. Replaced fuel pump, DME relay, and switched fuel pump relay with horn relay. Started, but problem returned next day.
6. Inspected wiring on all sensor connected to the fuse and corrected any sketchy parts
7. Verified that power is getting to the fuel pump with voltmeter (except when the DME fuse blows, of course)
8. Checked codes again. Besides those thrown by the fuse, there is an 'AC AUC sensor', 'terminal 30 defective' and 'thermal oil level sensor' errors that come up intermittently, but I don't know if they are connected to this at all.

WHAT AM I MISSING?!?!?! I have loved my BMW up until now, and troubleshooting has been a breeze. This is seriously making me consider torching it and collecting the insurance money. ANY help WHATSOEVER would be greatly appreciated. Oh, and it's disabled in my GF's parking spot, so our relationship is on the line, too!




My car: 200 BMW 328i, Manual, 115,000 miles, sport and luxury package

Thanks,

Jon

Seems like the AC compressor clutch is the only thing drawing from that fuse that you haven't checked yet. You'll have to crawl under the car and remove the plastic belly pan to get at the wiring to disconnect it

Crawled under there and didn't see any wiring plug. Only one I see going to the ac is the trigger wire on top of the ac, and it's hard to access and can only be seen from above. Is there another plug I'm missing?

Originally Posted by joncahill

Crawled under there and didn't see any wiring plug. Only one I see going to the ac is the trigger wire on top of the ac, and it's hard to access and can only be seen from above. Is there another plug I'm missing?

Wait wtf you live in my town. Dude let me see the car I'll help you in like two seconds no joke. I'm guessing your a pepperdine student?.

I actually live in Santa Monica now, but we are pretty close. If you have time to help ms out, I'll be back in town Monday (wedding), and would gladly pay you in beer, etc! I'm dying here! On top of it all, I move out of this place next Sunday, so I need to resolve it before then or I'm screwed royally.

Oh, and yea I'm a pepp law school grad. You?

Originally Posted by joncahill

I actually live in Santa Monica now, but we are pretty close. If you have time to help ms out, I'll be back in town Monday (wedding), and would gladly pay you in beer, etc! I'm dying here! On top of it all, I move out of this place next Sunday, so I need to resolve it before then or I'm screwed royally.

Originally Posted by joncahill

Oh, and yea I'm a pepp law school grad. You?

We can do this next week no problem bud. You can come by my house and will take a look at it. I work Mon-Fri and wont be home till around 5 or 6pm. Although I drive through Santa Monica on my way home from work usually. From what I see as he said above it may be the AC compressor but personally I believe you have a short some where. I'm usually pretty good and finding those. have you spilled water anywhere in the car recently?

And no I'm not a student. Just Malibu local, lived here my whole life basically

And on a nother note I found youa very useful link.
http://blog.bavauto.com/3744/bmw-e46...0-amp-blowing/
I'd say completely disconnect the AC compressor and see if it still happens. That's what I'd do if you were to come to my house. I'd also see how many volts the AC compressor is pulling compared to my car and see if they match.

Have you owned this car since new ? If not, does it have any aftermarket equipment (alarm, stereo, etc.) ? Just thinking that maybe a PO piggybacked something onto that circuit that you're not aware of....

Sent from my SPH-D700 using BimmerApp

Bought it used. No aftermarket equipment. Cowl is cracked though, water has def gotten back there, metal is rusty when I look back where the fuses/relays are behind the glove box . First thing ill fix once she starts!

Malibumafia- car doesn't run so I can't come to you unfortunately. You're welcome to stop by if I'm on the way to/from work. Any help would be appreciated. Another set of eyes/hands can sometimes make all the difference.

Thanks,
Jon

Originally Posted by joncahill

Bought it used. No aftermarket equipment. Cowl is cracked though, water has def gotten back there, metal is rusty when I look back where the fuses/relays are behind the glove box . First thing ill fix once she starts!

Malibumafia- car doesn't run so I can't come to you unfortunately. You're welcome to stop by if I'm on the way to/from work. Any help would be appreciated. Another set of eyes/hands can sometimes make all the difference.

Thanks,
Jon

Sent you a PM. If you know of water leaking where it shouldn't be. I bet will find a corroded connection most likely. I know it's probably a dumb question and you've already checked it but. Is your batteries positive and negative cables ok?

find a wiring diagram. trying to approach this without a diagram would be like trying to find a buried treasure without the treasure map.

http://wds.spaghetticoder.org/en/

ok so I got home last night from the wedding and got to work. Unplugged the AC clutch, and that didn't work. Wanted to test the SAP relay. Read on a forum, and some guy said the horn relay and the SAP relay were interchangeable! Well needless to say, they definitely are not! I learned this when the ground wire from the SAP relay burned all the way from the relay to the grounding point behind the passenger headlight!!! Huge puff of smoke, and a very distraught owner! So now I need to replace that wire. Anyway, the SAP relay I took off looked pretty bad, so I decided to simply leave it off and thus bypass the damaged SAP wires. Car started right up! It appears (knock on wood), that it was simply a bad SAP relay! Reconnected everything else (except SAP of course), and it still works.

New problem: connected by laptop to clear codes and check up on the car....and it will not recognize the DME (using BMW scanner 1.4.0). Any way I damaged DME/OBC functions or something? Only thing not connected at this point is the horn relay and SAP relay. Any ideas?



Lesson learned: not everything on the internet is correct....shocker!

This has been a very interesting story to follow. At least you are mobile now!

Jona just let me know if you still need help. You've got my #.

OH MY GOD THIS F*KING THING!! IT IS BACK!!

Started the car like 5 times last night and let it idle for a long time. Started her a few times this morning. And the problem with not talking to the DME disappeared. Cleared all codes, perfect! Re-assembled whole car. Started her, and she died 2 mins later!! Blown fuse again!!! This isn't even an electrical problem anymore, my car is just ****ing with me!

MalibuMafia, I may need to take you up on that help after all

ANY suggestions? This doesn't make ANY sense. I am officially on suicide watch now.........

Originally Posted by joncahill

OH MY GOD THIS F*KING THING!! IT IS BACK!!

Started the car like 5 times last night and let it idle for a long time. Started her a few times this morning. And the problem with not talking to the DME disappeared. Cleared all codes, perfect! Re-assembled whole car. Started her, and she died 2 mins later!! Blown fuse again!!! This isn't even an electrical problem anymore, my car is just ****ing with me!

MalibuMafia, I may need to take you up on that help after all

ANY suggestions? This doesn't make ANY sense. I am officially on suicide watch now.........

I really think it's just a bad ground wire. Have you checked all the ground wires established with what the fuse does? Even if a unit is plugged it doesn't mean it still wont cause a problem if say a negative and a positive is touching... lol.

If anything I know if I can't figure it out I know who can easily. Southbay autohaus it's located right off the 405 and roscrans. Ask for Qais and tell him I sent you. Hill help you over the phone to troubleshoot it if you mention you know me and I sent you.

Hey I appreciate it guys. I already gave up and sent it to a shop. Apparently the positive wire going to the leak diagnostic pump fried and was shorting. Never would have found it. All said and done- $700 to fix that and the SAP ground I fried. However, I'll need to replace the leak diagnostic pump soon (can't leave it disconnected forever).

And expensive learning experience I guess? Ughhb

Originally Posted by joncahill

Hey I appreciate it guys. I already gave up and sent it to a shop. Apparently the positive wire going to the leak diagnostic pump fried and was shorting. Never would have found it. All said and done- $700 to fix that and the SAP ground I fried. However, I'll need to replace the leak diagnostic pump soon (can't leave it disconnected forever).

And expensive learning experience I guess? Ughhb

I told you it was a bad ground wire... I could of found it for you for free

I know, and I'm sure you could have found it, but given my tight timetable I didn't have any room for error. That and my GF likes me again. Not cheap, but the stress and inconvenience was pretty bad.

Thank you all! And thanks malibumafia for offering to stop by! I'm moving up to Sacramento, so hopefully there are some good 'festers up there

Jon

Originally Posted by joncahill

I know, and I'm sure you could have found it, but given my tight timetable I didn't have any room for error. That and my GF likes me again. Not cheap, but the stress and inconvenience was pretty bad.

Thank you all! And thanks malibumafia for offering to stop by! I'm moving up to Sacramento, so hopefully there are some good 'festers up there

Jon

No problem man. If your ever around in town don't hestitate to say hello!. And glad you got your car fixed.

There is one and only one reason to blow a fuse: excess amperage. Excess aperage can come from several places. First and most obvious is a short. Second would be some type of motor/load failure causingthe amperage to spike.

You've pulled all the sensors and still have an issue. Since you've taken all of the loads offline, that suggests a short. You need to find the wire from the DME and locate its first stop. Rig a jumper around this stretch while removing the original wire from the circuit (don't want to back feed power to the shorted position).Continue with this till your fuse issue is resolved. Once you discover the offending circuit, "flat rate" a new wire in it's place.

Hope this helps. (I don't work on cars for a living, but I do chase electrical issues in automated equipment on a daily basis.)

OOPS...Now I see you have it fixed... Always a day late and a dollar short!