Invalid Data Received From Transfer Case Control Module

Where it lives

For U0403, start at the module the description names.

Check these first

• The Transfer Case Control Module sending data the ECM rejects as invalid
• A wiring or connector fault between the Transfer Case Control Module and the ECM
• Low voltage that corrupts the Transfer Case Control Module messages
• Software in the Transfer Case Control Module that is out of step with the ECM

What to do next

1. Read stored codes on every module and note codes paired with the Transfer Case Control Module code
2. Check the Transfer Case Control Module connector pins for corrosion or a poor fit
3. Test the wiring between the Transfer Case Control Module and the ECM
4. Check battery voltage and charging under load
5. Replace the Transfer Case Control Module if the data stays invalid
6. Clear the code and retest

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