Two questions: Voltage Reg and Electronics stay on

[express_wagon]

Hello,

1) For the Voltage Regulator, is it right on the alternator itself or is there another separate unit that is attached somewhere else? This is for a 1990 325is with stock M20.

2) My radio, on-board computer, and some other electronics are staying on even after I take out the key. What is the issue with this? I had a tough time searching for a definitive answer.

Thank you.

Jason

[DJB]

The voltage regulator is combined with the brush assembly. It's held onto the back of the alternator with two cap screws (likely #2 phillips or 8mm hex head). Remove the air box (loosen the two mounting points with a 10mm box wrench) for better access.

While you have the regulator out check the carbon brush length. New is 12mm, replace at 5mm.

The OBC LCD should remain on, with no backlight. It should display only the clock and not respond to button presses.

What other electronics remain on? Instrument cluster? Dash lights?

Does wiggling the ignition cylinder make a difference? What about removing the hazard light switch? (The latter causes weird symptoms when an internal diode fails.)

[AdamF 88iS]

2) My radio, on-board computer, and some other electronics are staying on even after I take out the key. What is the issue with this? I had a tough time searching for a definitive answer.

Thank you.

Jason

Pull fuses one by one to isolate where the short is. Any component that has batter power with the key off can short to ground and keep the ACC position stuff turned on. Once I had a customer car with a hazard switch that failed and caused the same symptoms.

[express_wagon]

So do you just remove the hazard switch? Do I have to replace it right away to see if that's the case?

[AdamF 88iS]

So do you just remove the hazard switch? Do I have to replace it right away to see if that's the case?

Well, thats what it happened to be in the case that I had to track down. If you unplug it and everything shuts off like it should with the key out then you know.

If that doesn't work, pull fuses one by one until everything shuts off. Then get a wiring diagram and see what components are on that fuse and remove those components one by one until everything shuts off. If that sill doesn't do it, you'll have to check for bad wiring or a bad ignition switch, both of which are very unlikely.

[Mystikal]

FYI: My car is also a '90 325iS, and I had the hardest time finding the voltage regulator (after I already purchased one). Turns out the Bentley manual as well as my usual resources failed to divulge the info that some cars came with Valeo alternators rather than Bosch; these units have an internal regulator, which isn't nearly as fun to change. I had the damn thing rebuilt.

-Jay

[express_wagon]

FYI: My car is also a '90 325iS, and I had the hardest time finding the voltage regulator (after I already purchased one). Turns out the Bentley manual as well as my usual resources failed to divulge the info that some cars came with Valeo alternators rather than Bosch; these units have an internal regulator, which isn't nearly as fun to change. I had the damn thing rebuilt.

-Jay

What if I have the Valeo, where is the VR located then?

Man, I really need to get a Bentley manual.

[Mystikal]

It's internal. Not easily replaceable.

-Jay

[express_wagon]

It's internal. Not easily replaceable.

-Jay

Well, then can't I just buy a brand new alt to take care of that?

[Mystikal]

Yep.

-Jay