E39 Ecu issues

[Dashao252]

I have an E39 and I was just gonna Get the ECU rebuilt because I am having various issues that point to it being the culprit. Headlights don't turn off. Only one headlight doesn't work. The transmission Gets stuck in second and I have to switch to Drive 3 and back to Drive to get it to shift. Speedo and odo stopped working randomly. im new the thread. Am I rite to assume ECU or does Anybody have any other ideas?

[328 Power 04]

No, the ECU doesn't deal with any of those.

You need to get a diagnostic scan of the entire car (looking for the faults in the transmission and engine computers), and likely get someone with electrics and wiring experience to look at the headlight switch, relays, and/or wiring for the headlights.

Don't go by assumptions, it will cost you much more in the long run.

- - - Updated - - -

Also, for what it's worth, all the ECU "rebuild" services don't actually rebuild anything. They visually inspect and check a few circuits *at best*. It's almost scammy.

If it's a known circuit or electronic ECU component that is faulty, as proven by correct diagnostics, then you can essentially get just that circuit looked at and repaired. But there's no one that will rebuild an ECU in the sense of making it like new. This is just wasted money.

[Dashao252]

Hey thanks for your input. After doing a little more research I learned you are rite every symptom has a list of things can be the issue. Like I have the Trifecta lit on my dash. And odo and speedo doesn't work. That could be abs module or one of the speed sensors. The trans not shifting could also be a speed sensor or transmission sensor. Thanks for your input. It made a difference. I'm now checking circuits and relays to rule those out.

[328 Power 04]

Do you have access to a scanner that can scan the ABS/DSC module, and other modules for BMW manufacturer codes?

I would consider the odometer, speedometer, and the transmission shifting issues as the same problem. You'll get a lot more information from the codes. It may be as simple as a wheels speed sensor or similar.

[hakentt]

ABS unit is known to short out CAN BUS communication creating many problems on E39