TCM DTCs Set on Vehicle Start Up

Some 2020-2022 Corvette models may have a Service Transmission message on the Driver Information Center (DIC), an illuminated Check Engine MIL and a squealing sound immediately after starting the engine. DTC P0700 (Transmission Control Module Requested Malfunction Indicator Lamp Illumination) may be stored in the Engine Control Module (ECM) and DTC P0606 (Control Module Processor Performance) or P0607 (Control Module Performance) may be stored in history the Transmission Control Module (TCM). Other P codes also may be set. This condition will be present on vehicle start up only (Fig. 26) and not when the vehicle is in motion.

Fig. 26

The DIC transmission message and possible squealing sound are default actions of the DTC as the TCM is in a defaulted state and may not be controlling line pressure, resulting in the transmission operating a maximum line pressure.

DTC P0700 is an informational DTC. Do not replace the control module if DTC P0700 is set.

If DTC P0606 or P0607 is set as a current DTC in the TCM, without other DTCs set, follow the published diagnostics in the appropriate Service Information. The condition should be resolved by allowing the vehicle to go through a complete sleep cycle (i.e., 15 minutes). Explain to customers that they can complete this process if they experience the condition again before a correction is available.

If DTC P0606 or P0607 is set as a history DTC in the TCM with other P codes (e.g., P07E5 or P07E6), the other codes are a byproduct of the controller state. Do not replace the TCM for P0606/P0607 when other P codes are present or when DTCs P0606/P0607 are in history. If DTCs P0606/P0607 are in history, clear the codes and test drive the vehicle to make sure the DTCs do not return. If the DTCs do not set again, return the vehicle to the customer. Permanent repair information will be released when available.

For more information, refer to #PIP5852.

– Thanks to Steve Schipansky

Using R-99 or R-95 Diesel Fuel
June Service Newsletter from the Experts at GM TAC

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