A P0603 on the Duramax indicates a keep-alive memory (KAM) error in the control module, often tied to power supply or a module problem.
What P0603 means
Control Module Keep-Alive Memory Error is a diagnostic trouble code set when the monitored value falls outside its expected range. On the Duramax, it narrows the problem to a specific system, and reading it correctly prevents replacing good parts.
Common causes
- Weak or failing batteries
- Corroded or loose battery and ground connections
- Recent battery disconnect without relearn
- Control module fault
Symptoms you may notice
- Check-engine light
- Possible drivability or shifting quirks
- Relearned adaptive values
- Intermittent electrical faults
How to diagnose it
Start with the batteries and connections, since KAM errors often follow low voltage or a disconnect. Verify battery health, clean grounds, and check for parasitic drains. Persistent errors with good power may indicate the module.
How to fix it
Repair battery and ground issues and perform any required relearn after a disconnect. If the fault persists with good power, the module may need attention. Clear the code and verify normal operation.
Frequently asked questions
What is a KAM error?
A keep-alive memory fault in the control module, often triggered by low voltage, a battery disconnect, or a bad connection.
Do I need to relearn after a battery disconnect?
Some adaptive values relearn on their own with driving; verify normal operation and address any lingering codes.
Is the module bad?
Usually it is power-related. Fix batteries and grounds first; a persistent error with good power may point to the module.
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