ELectrical issues, please help 550i

[MJ535]

I recently (tow months ago) bought a 2010 550i GT. Just recently I have been having peculiar electrical issues. It only happens in the morning or after the car has been sitting. For example I drove the car on a 400 mile round trip to visit family yesterday. No issues. I go to start it this morning and I get the dreaded Drivetrain Malfunction message. The car starts and runs fine but won't shift into gear. I used my Carly adapter to pull the codes and they all seem to related to system voltage:

ABS
Code D36C22 - Error signal height Channel EHC - Invalidlow

Transmission
Code 420531 - Power Amplifiers: Short Circuit to Ground

Systems
Junction Box - Code C90D60: K-LIN 6 x AUX Sensor - Internal Error
Central Control - Code 801405: Undervoltage Detected

My experience has been that I can let the car warm up, reset the codes and go. Takes a while.

The battery is 2 years old (manufacture date), genuine BMW and looks fine.

Any idea where I should start looking. The transmission one is the scary one.

I am missing the super simple and reliable 530i I sold when I bought this one.

Thanks.

Mark

[f10_M550i]

I recently (tow months ago) bought a 2010 550i GT. Just recently I have been having peculiar electrical issues. It only happens in the morning or after the car has been sitting. For example I drove the car on a 400 mile round trip to visit family yesterday. No issues. I go to start it this morning and I get the dreaded Drivetrain Malfunction message. The car starts and runs fine but won't shift into gear. I used my Carly adapter to pull the codes and they all seem to related to system voltage:

ABS
Code D36C22 - Error signal height Channel EHC - Invalidlow

Transmission
Code 420531 - Power Amplifiers: Short Circuit to Ground

Systems
Junction Box - Code C90D60: K-LIN 6 x AUX Sensor - Internal Error
Central Control - Code 801405: Undervoltage Detected

My experience has been that I can let the car warm up, reset the codes and go. Takes a while.

The battery is 2 years old (manufacture date), genuine BMW and looks fine.

Any idea where I should start looking. The transmission one is the scary one.

I am missing the super simple and reliable 530i I sold when I bought this one.

Thanks.

Mark

most obvious thing to me is that it may be time for a new alternator. (assumption: original alternator in the car). a bad alternator can throw all kinds of weird electrical issue. you can check it by using a voltage meter on the battery terminals with everything electrical running and turned on, it should read approx. 13.5 volts. You can also check it via the hidden OBD menu from the instrument cluster. (menu has to be unlocked first using the last 5 of your VIN) This would be my next step. If that checks out, you should take it to a shop that has ISTA and get it properly diagnosed.

[MJ535]

For additional clarity, these errors pop up and I get the powertrain malfunction message on the dash when I open the door in the morning prior to starting or even getting into the car despite that when I parked it there were no issues.

[jclausen]

I would check the alternator

[f10_M550i]

For additional clarity, these errors pop up and I get the powertrain malfunction message on the dash when I open the door in the morning prior to starting or even getting into the car despite that when I parked it there were no issues.

probable symptoms of diminished voltage level on a battery as a result of not getting a full charge from the alternator.

[MJ535]

Continuing to research this issue. Could this be the integrated supply module? Any experience with this part that controls some of the voltage.

Mark

[White94RX]

I doubt it. The IVM supplies power to the valvetronic, injectors, and probably coils too. You don't have faults for any of those components.

[MJ535]

Thanks Russ, that makes sense.

It hasn't happened in a couple days. I will get the opportunity to test the alternator this weekend.

Mark

[White94RX]

I'm trying to figure out which code is turning on the drivetrain malfunction light. It's got to be the transmission code. Power amplifier? I'm not even sure I've ever seen that code before. But a short to ground fault probably isn't voltage related.

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[MJ535]

I have narrowed this down to moisture getting into the electrical system and causing havoc. It only happens when it's wet. If I warm the car up after the Drivetrain Malfunction comes on, shut it down and come back in a few minutes it's starts up and drives just fine. Maybe it's still a relay, but I think moisture in getting into the transmission controls.

[MJ535]

I'm trying to figure out which code is turning on the drivetrain malfunction light. It's got to be the transmission code. Power amplifier? I'm not even sure I've ever seen that code before. But a short to ground fault probably isn't voltage related.

Sent from my Pixel XL using Tapatalk

I believe relay and power amplifier are used equivalently. Would it make sense to target a particular relay?

Mark

[DylanL]

Hey Mark

Have you been able to solve the issue?

Ive got the same transmission code. Im able to unplug the neg battery cable for a min then i can start it no problem. I would like to solve the issue but cant seem to figure it out.