GM Service Manual Online
For 1990-2009 cars only

Circuit Description

Internal defects in the theft deterrent module (TDM) set DTC 55.

Conditions for Setting the DTC

Theft deterrent module hardware failure (EEPROM, RAM, ROM defective).

Action Taken When the DTC Sets

The engine will not start.

Conditions for Clearing the DTC

    • Replacing the theft deterrent module.
    • A history DTC will clear after 20 consecutive ignition cycles if the condition for the fault is no longer present.
    • Use a scan tool in order to clear this DTC.

Diagnostic Aids

    • Before replacing the TDM, always inspect the power and ground circuits to the module.
    • Replace the TDM if the power and ground circuits are OK.