Trans Failsafe Prog today
 

3.0 M54 with GM Transmission.

Got the "Trans Fail Safe Prog" across the bottom of the cluster + yellow brake light today after only driving 5 mins. Car felt like it had loss of power for split second a couple of times (not a trans slip) and changed up and down through the gears fine otherwise.
Error message still up when reached destination, turned ignition off and on again-error message had cleared.

Scanned for codes when I got home- TCM code "97 CAN status, fault" ?
Scanned all other modules on the CAN circuit (DME, DSC, Cluster etc) no other codes.

Voltage fine with ignition off and on (12.4v & 13.9v)

Took it for a drive and monitored a few things with the scanner- Brake switch activation OK. All trans activations working as they should, All speeds sensors reading correct etc.

Cleared code. Took it for a drive up around a Mountain pass to load it up, trans ran and shifted flawlessly.
No warnings or codes since.

I replaced the trans fluid when I first got the car about a year ago- 3x drain and fill with Valvoline Maxlife ATF, new bmw filter.
Never any issues before today.


Anyone experienced anything similar? Any ideas what might have caused that one off situation?

Well from what I can tell you have a bad brake light switch at the brake pedal.

Well going bad as it didn't pop back up instantly.

I had that once in my e38 (5HP30). Battery nap and I never saw it again.

Fitted a new BMW brake switch at the pedal and all seems well now.

Not sure if the old one was failing or the adjustment had been disrupted, but so far so good with the new switch :thumbup: