G8 goes on limp mode after reflashing.

[[email protected]]

Folks,

I reflashed ECM and TCM because my car got the valve body and TCM replaced. Drove the car for about 20 miles then the contact dealer warning came up, followed by downshift to 2nd gear, then ABS Fault light and Stability Control light. After that the car was basically in limp mode, stuck in 2nd gear and then instrument panel went crazy. It happened twice after re-flashing and driving the car for about 20 miles.


[ECM] P0700 - Transmission Control System Malfunction
[ECM] P0575 - Cruise Control Related Malfunction (History) (Immature)
[ECM] P0856 - Traction Control Input Signal (Old) (History) (Immature)
[TCM] U0073 - Control Module Communication Bus Off



Is it possible that somehow i got a short, or there's something by plugging hptuners that's causing this issue?

Thanks in advance,
Alex

[[email protected]]

Anyone?

[Napalm]

I hear its common for a g8 to lose connection to the TCM after a read. maybe even a flash.

On mine I have had to pull the TCM fuse to re-set the module. Or pull the negative battery cable.

Try that.

[5_Liter_Eater]

Not sure if it applies but are you currently running SD? There is a TCS patch because putting some 4th gens in SD mode triggers similar TCS errors. Go into OS, General and see if there is a TCS patch available. If so apply it and write entire.

[[email protected]]

I hear its common for a g8 to lose connection to the TCM after a read. maybe even a flash.

On mine I have had to pull the TCM fuse to re-set the module. Or pull the negative battery cable.

Try that.

Tried that and it didn't work. I took the car to the dealer on Tuesday and supposedly found the Trans Connector pins backed out of the connector, they rebuilt the connector test drove without any issues after this. So i got the car back on Tuesday afternoon, drove it for 150 miles with no issues. Yesterday i connected hp tuners to re-flash the ECM and TCM because the dealer reflashed the TCM to stock, then drove the car back from work to home (about 35miles) without issues. Today on my way to work it happened again! The first thing that popped up was the contact dealer warning, then it started locking and unlocking the doors while driving, abs fault light came up, Stability control, check engine, and shifted down to 2nd gear. What's going on?!!?!?!

[[email protected]]

Not sure if it applies but are you currently running SD? There is a TCS patch because putting some 4th gens in SD mode triggers similar TCS errors. Go into OS, General and see if there is a TCS patch available. If so apply it and write entire.

No, the car is not running SD, but it has an LS3 3bar MAP with the proper calibration. Looked under OS and it looks the TCS patch is available but not applied. VATS1/2 and Starter Checks are enabled.

[ElecTech]

Are you re-reading your car and applying the changes to the new TCM OS prior to reflashing? If you are just slapping your old TCM tune back in, this may be the issue.

When the "returned it to stock" I assume they did an OS update.

[tpy2kws6]

What was the final outcome on this problem?