As part of the vehicle telematics enhanced services, a request may be sent to the theft deterrent module (TDM) to disable vehicle starting. If a valid message is received by the TDM requesting that starting be disabled, the start enable message will not be sent to the engine control module (ECM).

A valid start disable from telematics will set DTC  B302A only as a history DTC.

Vehicle starting will be suspended and the security indicator will be illuminated.

A history DTC will a scan tool is used to clear DTCs or after 100 ignition cycles in which the telematic start disable request is not seen.

DTC B302A is only an indicator that a start disable request has been received from the vehicle telematics system and does not indicate a fault in the vehicle theft deterrent system. B302A will only set as a history DTC. The only procedure required is to clear the DTC with a scan tool.

Schematic Reference

Immobilizer Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Immobilizer Description and Operation

Electrical Information Reference

Scan Tool Reference

1. Verify the OnStar system is operating properly.
2. With a master vehicle key, turn the ignition ON.
3. Observe the security indicator. After approximately 10 minutes, the indicator will turn OFF.
4. Turn the ignition OFF and wait 5 seconds.
5. Repeat steps 2-4 two more times for a total of 3 cycles or 30 minutes.
6. With a master vehicle key, turn the ignition ON. The start disable will now be cleared.
7. With a scan tool, clear any DTCs.

Perform the Diagnostic Repair Verification after completing the repair.