Mom's new 2003 525i Touring has a few electrical issues

[LysanderSpooner]

I just found a really nice E39 wagon for my mom to tool around in, and she's loving it. It does have a few electrical problems that I am hoping I can clear up with a little help.

1. The radio (Business Class CD) makes really pretty lights when you turn it on, but it makes absolutely no sounds. From what I have read here and elsewhere it's likely that the amp is blown. I'll be looking for alternatives such as scoring a working one at the local pick-a-part, or more likely an aftermarket solution. I'm not really looking for specific advice on the radio in this thread (though go ahead if you wish), but rather I'm including it in the mix of other problems that I will detail below, just in case there are connections to be made.

2. The interior lights don't come on when you open the doors. I had an old Mercedes once that had this same issue (plus a non-functional key warning buzzer; mom's buzzer now works fine*), and the fix was a simple relay replacement. I have checked all fuses, and the dome lamp bulb passes current, but there just isn't any juice being delivered to it. The map lights don't work either, for what that's worth.

3. The brand new remote key we just dished out $236 for doesn't do squat, electronically speaking. Five different techs took a stab at it at the dealership with no luc, and I tried it a few times myself. The process I found is to cycle the key quickly (~1 sec.) on/off in the ignition switch, pull it out, hold down the unlock button, then press the lock button three times, all of this with the doors closed and locked, and seat belts on. As I said, squat. Zilch. Nada.

One thing I read elsewhere that I am leaning toward as the root cause of at least #2 & 3 is the possibility of broken wiring at the rear hatch hinges. I understand there is a an antenna embedded in the rear glass that is used by the keyless system. And come to think of it, I'm not sure that rear hatch light is still working now. I do know that mom and I both saw it come on though.

So... little help here? Mom likes her Jazz 88... and dome lights and stuff.

*When we got the car, the left front turn signal wires were cut inside the engine compartment. After soldering them back together, in addition to the signal now working, the ignition key warning buzzer and rear hatch overhead light both came to life. Prior to that they were both non-functional.

[ColtonBH]

I might have an amp for you

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[LysanderSpooner]

I just found a really nice E39 wagon for my mom to tool around in, and she's loving it. It does have a few electrical problems that I am hoping I can clear up with a little help.

1. The radio (Business Class CD) makes really pretty lights when you turn it on, but it makes absolutely no sounds. From what I have read here and elsewhere it's likely that the amp is blown. I'll be looking for alternatives such as scoring a working one at the local pick-a-part, or more likely an aftermarket solution. I'm not really looking for specific advice on the radio in this thread (though go ahead if you wish), but rather I'm including it in the mix of other problems that I will detail below, just in case there are connections to be made.

2. The interior lights don't come on when you open the doors. I had an old Mercedes once that had this same issue (plus a non-functional key warning buzzer; mom's buzzer now works fine*), and the fix was a simple relay replacement. I have checked all fuses, and the dome lamp bulb passes current, but there just isn't any juice being delivered to it. The map lights don't work either, for what that's worth.

3. The brand new remote key we just dished out $236 for doesn't do squat, electronically speaking. Five different techs took a stab at it at the dealership with no luc, and I tried it a few times myself. The process I found is to cycle the key quickly (~1 sec.) on/off in the ignition switch, pull it out, hold down the unlock button, then press the lock button three times, all of this with the doors closed and locked, and seat belts on. As I said, squat. Zilch. Nada.

One thing I read elsewhere that I am leaning toward as the root cause of at least #2 & 3 is the possibility of broken wiring at the rear hatch hinges. I understand there is a an antenna embedded in the rear glass that is used by the keyless system. And come to think of it, I'm not sure that rear hatch light is still working now. I do know that mom and I both saw it come on though.

So... little help here? Mom likes her Jazz 88... and dome lights and stuff.

*When we got the car, the left front turn signal wires were cut inside the engine compartment. After soldering them back together, in addition to the signal now working, the ignition key warning buzzer and rear hatch overhead light both came to life. Prior to that they were both non-functional.

ColtonBH's offer of an amp turned out to not be the answer, as his was a DSP amp and our radio is not DSP. So off to the pick-apart I went and found a good working one. Problem #1 is now solved.

Numbers 2 & 3 are still a challenge. Today I will be installing new rear hatch struts, and whilst doing so I will be checking all hatch wiring very closely for signs of failure there. The odd thing is the trunk release button on the key works, just not the locking buttons. This points toward the rear hatch antenna not being the root of the key issue, yeah?

I'm also still baffled by the interior lights not coming on. Is there a relay involved? No wonder I can't sleep at night... ;-)

[ColtonBH]

Does it not turn the lights on for ant doors or just the drivers?

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[LysanderSpooner]

Does it not turn the lights on for ant doors or just the drivers?

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No ant doors, nor any doors, nuttin'... ;-)

[ColtonBH]

XD

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[LysanderSpooner]

Well... at least the rear hatch struts weren't too hard to install. I saw no signs of wiring damage in the hinge area, which jives with A below.

So... some more clues:

A. The remote key operates the rear hatch, so I assume pairing was done successfully.
B. There was all kinds of gunk in the master door lock switch in the center console, so I replaced it.
C. There is no hood latch sensor switch. I currently have the plug jumpered so that the car thinks the hood is always closed.
D. The map lights front and rear work fine, as does the glove box light and rear hatch light.
E. There are three wires in the front grille area that are clipped (brown, yellow/gray, black/gray). See the photo below.

IMG_2100.jpg

[LysanderSpooner]

A little more digging brought me to the conclusion that the GM3 located behind the glovebox was the culprit. In addition to the other issues I mentioned previously, the car also had really heavy steering at slow speeds. Turns out the GM3 also controls the Servotronic steering system...

Being the adventuresome type, I took the unit apart and saw four capacitors inside. More digging brought up some posts about successfully replacing these capacitors in the GM units on older model cars, so off to the local electronics store I went. I soldered the new caps in one at a time (remove just one, solder a new one in its place, remove the next one, etc... this was suggested with the idea that the unit would have a better chance of retaining its settings), making sure to get the polarity correct, and doing a pretty nice tidy job of it if I do say so myself...

And then I reinstalled it, forgetting to disconnect the battery first. I don't know if this killed it, or if the repair failed, but now nothing worked... no interior lights, no Servotronic, nuthin...

Next up was a trip to the local breakers, from where I brought home three units from sedans of similar vintage, showing the same part number on the outside. As soon as I popped in a "new" one, Servotronic and the interior lights started working, hurray!

Now I just have to get the remote locking to work. As I mentioned before, the key operates the rear hatch remotely, so I'm assuming it's paired. Should I expect that having the GM3 recoded will bring the remote locking back to life?

At least I'm making progress, which feels gooooood.