Update on Auto Transmission light

[mrw187]

re:
https://z4-forum.com/forum/viewtopic.php?p=2027641#p2027641

04 BMW Z4 is limp mode with transmission light and giving solenoid errors upon scanning.

Took it to a transmission specialist:

They dropped the pan
checked all the solenoids - all good
checked the wiring from the solenoids to the plug on the outside - all good

everything inside the transmission is fine

problem in wiring from transmission to control unit or problem in control unit itself

Since they were only a trans specialist they recommended taking it to an auto electrician.


How major does this sound? Price range?

 

[bigwinn]

I recall on a previous thread a few replies said to check your selector switch?? It’s the commonest fault that throws a transmission light

Have you removed and cleaned it?

 

[mrw187]

I recall on a previous thread a few replies said to check your selector switch?? It’s the commonest fault that throws a transmission light

Have you removed and cleaned it?

No, I'm not mechanically inclined unfortunately.
Could this selector switch throw up solenoid errors on both a carly scan and when they scanned it with their own pro tool as well?

 

[Matty_Z4]

I recall on a previous thread a few replies said to check your selector switch?? It’s the commonest fault that throws a transmission light

Have you removed and cleaned it?

No, I'm not mechanically inclined unfortunately.
Could this selector switch throw up solenoid errors on both a carly scan and when they scanned it with their own pro tool as well?

If the electrical connector gets water in it you will see a whole host of codes and can go into limp mode. For the moment mine is just gunked up with silicone to keep it dry until I need to change the connector/switch.

I have seen speed sensor codes and solenoid codes on my car when the plug was damp both times went into limp mode and only allowed gear 3.

 

[mrw187]

I recall on a previous thread a few replies said to check your selector switch?? It’s the commonest fault that throws a transmission light

Have you removed and cleaned it?

No, I'm not mechanically inclined unfortunately.
Could this selector switch throw up solenoid errors on both a carly scan and when they scanned it with their own pro tool as well?

If the electrical connector gets water in it you will see a whole host of codes and can go into limp mode. For the moment mine is just gunked up with silicone to keep it dry until I need to change the connector/switch.

I have seen speed sensor codes and solenoid codes on my car when the plug was damp both times went into limp mode and only allowed gear 3.

oh ok, so, is that what its called the electrical connector? where is it located? Just so i know and present the idea to the auto electrician while im there

 

[Johnbmwz4]

I had my auto transmission switch replaced in my old E85 for around £300 if I remember rightly. It was the gearbox specialist who did the job though not an auto electrician.

 

[mrw187]

TCM 3 problems exist
Pressure Actuator 3 P0700, P0798
Pressure Actuator 2 P0700, P0778
Pressure Actuator 4 P0743

Dropped transmission pan and resistance tested solenoids, OK
Checked internal wiring loom, OK
Checked fuses and visually checked wiring & connectors, no fault found

Appears to be a broken connection from TCM to trans, or a faulty TCM.


That was the transmission specialist diagnosis and they recommended taking it to an auto electrician.


The gears do clunk a little when going from park to reverse/park to drive/reverse to drive/drive to reverse.
I may have heard wrong but the trans guy reckons the solenoids are out of action to apply the correct pressure or something.

 

[Matty_Z4]

No, I'm not mechanically inclined unfortunately.
Could this selector switch throw up solenoid errors on both a carly scan and when they scanned it with their own pro tool as well?

If the electrical connector gets water in it you will see a whole host of codes and can go into limp mode. For the moment mine is just gunked up with silicone to keep it dry until I need to change the connector/switch.

I have seen speed sensor codes and solenoid codes on my car when the plug was damp both times went into limp mode and only allowed gear 3.

oh ok, so, is that what its called the electrical connector? where is it located? Just so i know and present the idea to the auto electrician while im there

On mine its water getting into the black plug on the left of this photo so my mechanic just sealed it up with a bunch of silicone after cleaning it out and using some contact cleaner. This plug does seem to be part of the selector switch so is might be better to get that replaced/repaired as others have suggested.

Your welcome to try a "temporary" repair like mine by disconnecting the plug, cleaning with contact cleaner/drying out and then re assembling to see if the problem goes away.