GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Vivant 🢒 Transmission/Transaxle 🢒 Automatic Transmission - ZF 4HP 16 🢒 DTC P0603

Circuit Description

A normal function of the transmission control module (TCM) programming is to perform an internal check that verifies the integrity of the keep alive memory (KAM) allocations.

The DTC P0603 sets when the KAM is not operating correctly when checked on initialization. An area of KAM is failed a read/write test.

Conditions for Setting the DTC
    • The checksum of the current regulator data will be tested. If the checksum is not OK, then the error bit will be set.
    • If writing to FLASH during power latch phase failed
    • Each of the flash blocks has its own status which is located at the beginning of each flash block and the status of the FLASH blocks do not fit together.
    • The system voltage is too high or too low.
    • The transaxle input voltage is too high or too low.

Action Taken When the DTC Sets
    • The malfunction indicator lamp (MIL) will illuminate.
    • The TCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffer.
    • Adopt Emergency/Substitute mode and constant 4th gear by hydraulic control.
    • After ignition OFF/ON: 3rd gear by hydraulic control. Possible P, R, and N also possible.
    • Power supply cut off to the PCS valve.

Conditions for Clearing the MIL/DTC
    • A MIL will turn OFF when the malfunction has not occurred after 3 ignition cycles.
    • A history DTC will clear after 40 consecutive warm-up cycles without a fault.
    • Using a scan tool can clear history DTCs.

Diagnostic Aids

When DTC P0603 sets, the possible cause of the fault could be the TCM.

Step

Action

Yes

No

1

Did you perform the Diagnostic System Check-Automatic Transmission?

Go to Step 2

Go to Diagnostic System Check - Automatic Transmission

2
  1. Install the scan tool.
  2. Turn ON the ignition, with the engine OFF.

Does the scan tool display DTC P0603?

Go to Step 3

Go to Diagnostic Aids

3
  1. Turn OFF the ignition.
  2. Replace the transmission control module (TCM). Refer to Transmission Control Module Replacement .

Is the action complete?

Go to Step 4

--

4
  1. Using the scan tool, clear the DTCs.
  2. Road test the vehicle within the Conditions for Setting this DTC as specified in the text.

Does the scan tool indicate that this diagnostic has run and passed?

Go to Step 5

Go to Step 2

5

Check if any DTCs are set.

Are any DTCs displayed that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List/Type

System OK