Battery drain, dash light issues, top & windows non-fucntional, etc..

jesseicp · Post by **jesseicp** » Thu Mar 16, 2017 6:09 pm

I have a 2003 BMW Z4 2.5i Sport. About a year and a half ago, I started having some electrical issues, most of which have gotten worse. I can't remember the exact progression of these things, but some of them started before others, though all began within a two month period. The top doesn't go up or down (red lights don't even come on anymore when the button is pressed), the windows don't go up or down (unless operated with the key in the door), the key fob intermittently will not operate the locks or trunk release, the A/C only works sometimes if the A/C was turned on before shutting the car off and starting the car again, the instrument cluster looks like a Christmas tree, the turn signal indicators don't light up (exterior signals do flash though), high beam indicator doesn't light up (high beams work), the battery drains while the car is off, the dash lights stay on when the car is shut off (probably the cause of the battery drain), the dash light dimmer is non-functional and the CD player reads <Disabled>. When the car is first started, the dash lights shut off and it takes around two minutes for them to come back on, but then do not turn back off when the car is shut off. I've installed a negative terminal switch in the trunk that I've been using every time I drive the car to avoid the battery drain since the issue began.

One thing that I've tried recently, after reading a little about people having similar issues, is replacing the relays in the GM5 module. This probably wasn't a good place to start, but like I said, I'm a little lost as to where to look next. Unfortunately, after replacing the relays, the car is starting intermittently. I'm not sure how this affected it, as I read that the car should run fine even with the module removed from the car, but my guess is that something related to the electrical issues I've been having worsened with the GM5 module removed. The relay swap went reasonably well and when I put the module back in, the door locks are functioning fine (which they did before I changed the relays as well), however the car doesn't want to start 3/4 of the time when the key is turned.

I feel like I need to start by chasing down the culprit of the electrical issue. I think that the two issues are probably related, but I need to start somewhere. It's possible that they aren't, but if I can fix the electrical issue with the car off, that at least gives me a starting point.

Right before these issues began, I installed coilovers and threw new 19" wheels on the car. If I didn't have so much money invested in it, this issue has gotten out of control enough that I might even consider having to sell the car. I've really loved my Z4 for the 6 years that I've owned it though, and really hope that someone can offer me some sort of advice to help get the car back into shape before the summer.

Thanks in advance for any advice that anyone can offer!

Mike6 · Post by **Mike6** » Thu Mar 16, 2017 6:49 pm

I am sure someone with more knowledge will be along shortly but how about earthing problems as a start.

jesseicp · Post by **jesseicp** » Thu Mar 16, 2017 6:53 pm

Thanks for the response! I think that it could very well be some sort of an earthing issue, but I'm not sure where to start testing at this point.

Just went out and tested the battery, which is only 2 years old. 12.58v.

Scooba_Steve · Post by **Scooba_Steve** » Thu Mar 16, 2017 7:31 pm

Has it been sat for a few hours before you've measured the voltage? It's only a rough guide but does need time to settle.

jesseicp · Post by **jesseicp** » Thu Mar 16, 2017 7:35 pm

The last time it was ran was approximately four hours before checking the voltage on the battery. I should also add that on top of the battery only being two years old, I've been driving it with these issues for the past year and a half. This being said, if it were somehow a battery issue, the battery would have been six months old when it failed.

jesseicp · Post by **jesseicp** » Fri Mar 17, 2017 3:09 am

The Good News:
After a year and a half of dealing with these issues, making this post and spending the majority of today messing around with various things and rooting through forums, I have finally found the resolution to this issue: the air bag module.

It was this thread that led me to believe the air bag module could be the cause: viewtopic.php?f=3&t=86125

His issues were exactly identical to mine in every way, so I headed out to the garage and tore apart the center console so that I could disconnect the module. When I unplugged the harness that brings power into the module, I noticed a lot of corrosion on the plug. When I put the key in the ignition and watched for the turn signal indicator to work, it finally lit up! The windows are back to working and the power top latch functions! All the crazy electrical issues are resolved.

Now I'll look into purchasing another airbag module and getting it coded after replacement.

The Bad News:
The intermittent starting issues remain. Either I've messed something up on the GM5 module when I changed the relays (unlikely since everything works now, including the key fob to unlock the doors) or something else just happened to fail at the same time that I messed around with the module. I'm guessing that either the battery, starter or ignition switch has gone bad, all of which have been replaced within the last several years on this car, so it is pretty interesting.

Also, my power top motor is not working. This was an issue that had started right before the crazy electrical issues began. I just assumed that the problem got worse when it stopped unlatching at the same time that the other electrical issues showed up. Now that I've resolved the electrical issues, the latch is back to operating at the touch of the button, but the top is still not mobile. Looks like I'll be tearing that down to replace or repair the top motor as well.

In the end, I'm happy that I've finally made some progress with the car. It feels a little less like a lost cause now. I've put a lot of work into trying to locate the cause of this issue with no results, so it was really doing a number on the reward system, lol. Just thought I'd update this thread for anyone that stumbles upon it in the future with similar issues. Thanks to those who responded!

Rufus59 · Post by **Rufus59** » Fri Mar 17, 2017 2:34 pm

Have you had the modules scanned for codes? Would have thought you could rule out the ignition switch through diagnosis in dis or inpa.

Starter does seem to be a reasonably common issues on these. My old e85 had it, something to do with the solenoid sticking. Someone with more knowledge would probably be able to tell you how to test this using a multimeter to measure amps drawn by the starter.

When you say it won't start, is it even cranking/turning over?

jesseicp · Post by **jesseicp** » Fri Mar 17, 2017 3:11 pm

I haven't had the modules scanned for codes. I purchased the cable and installed all the software last year, but my main objective at that point was to get rid of the airbag light staying on (came on when I unplugged the airbag sensor under the seat without disconnecting the battery). I was never able to get the software to communicate with the airbag module to reset the code for the light, but now I know that it's because the module failed at some point after the light came on, but before I got the software set up. I'll have to grab the laptop that I have everything set up on from the office and see what kind of results I get with it now that the electrical issues have been corrected. It will probably work as it should and I can finally start to familiarize myself with it.

It doesn't crank over when it fails to start and the starter doesn't try to engage. When the car does start, however, as this issue has been intermittent, the starter and battery show no signs of weakness in the form of sluggishness.

Interestingly enough, I left the battery trickle charging last night and I've tried to start the car four times so far this morning. Each time, the car has fired right up. I'll check it a couple more times throughout the day, as well as leaving it on the charger. This should ensure that it stays fully charged if the battery is starting to fail. If the issue doesn't return until I disconnect the charger for awhile, I'll replace the battery.

In a way, the battery would be the component that seems the most likely point of failure in this case. Out of the starter, ignition switch and battery that have been replaced, the battery was the least recent. The battery drain issue has probably also been extremely harsh on it. I usually don't forget to flip my negative terminal switch in the trunk when I park the car, but I have several times. When this would happen, the battery would fully drain and this happened more than a few times, including during the winter where it could sit for extended periods of time in freezing temperatures with a dead battery. I hadn't experienced issues with starting prior to the GM5 module removal, no, but it's certainly reasonable that the battery failing at the same time that I pulled the module is just a nasty coincidence.

Mike6 · Post by **Mike6** » Fri Mar 17, 2017 6:58 pm

Have you checked the main lead to the starter for proper connection. Also any loose connections on the solenoid.

CHUCKNADO · Post by **CHUCKNADO** » Sun Jul 26, 2020 8:28 am

Sorry to dig up old post... but this is exactly what I'm going thru right now. Albeit not quite so bad..

I left the roof off w
In the rain and came back to a soggy car and a few faults...

Can't wait to give this a try

Cheers

C

jesseicp · Post by **jesseicp** » Sun Jul 26, 2020 4:44 pm

The failed starting issue progressively got worse until finally it would never start. The car sat for several months while I tried to troubleshoot it unsuccessfully. Finally, thinking that it would be a PCM issue, I sent the key, EWS module, gauge cluster and PCM into a service to have them flashed as I read on many other forums that reflashing the PCM often fixed issues like these.

When the guy received all of my parts and started working on them, he quickly realized that the issue I was having was simply caused by a bad key transponder, causing it not to be able to properly communicate with a car.

After changing the transponder, the car started properly, but this broke functionality of the buttons on the key fob to repair the transponder. Finally I wound up swapping to a new key by buying an AK90 and coding my own key. This however did not resolve the battery draining portion of the issue, only the starting.

After searching around forever, I finally found that the airbag module had failed by getting water into the connector someplace and several of the pins had corroded away. replacement and recoating of the airbag module resolve the rest of the issues. The car now starts properly, I'm still driving it, and no more battery draining issues or malfunctioning electronics.

CHUCKNADO · Post by **CHUCKNADO** » Wed Aug 19, 2020 2:45 pm

This is amazing, i tried this on my car and everything is back up and running... thank you everyone

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