ECU/ECM, car does not stay started

VVERDEKAL

MEMBER
2014 GMC TERRAIN
2.4L
4 CYL
2WD
AUTOMATIC
89,000 MILES

ECU problems, U401 codes popped up, 3 to be exact. Car runs but says there is a problem with ECU communications. So I got a new programmed ECU from a company, "programmed" and both replacements sent throw a camshaft position sensor unlearned. So my car runs and cranks with old ECU. The new (2) I've replaced doesn't crank at all. My car shuts off as I turn the key. Check engine light just blinks. I can't relearn the crank position because it has to run. Any help would be grateful.

1 Reply

JONNYB1963

MECHANIC
252 POSTS

Okay, I need to catch up here.

You stated that you had received a "U401" which means invalid data was received from the ECM/PCM.

First, its important to note that nowadays, all modules are called ECM's so its important to specify exactly which one we are discussing. (For example: PCM, IPC, ABS, RCM, PAM PACM etc.)

The important thing to know here is exactly which module was reporting the DTC code. For example I will see DTC codes from several different modules in the vehicle each stating Invalid Data received from the ABS module.

Was it the PCM itself reporting the problem? Were there any other DTC codes present in any other modules at the same time?

Was a Self-test performed on the PCM?

Let me know!
Jon