Immobilizer System Check

NOTE: When conditions for setting fault code are no longer present, DTC will clear after 20 ignition switch ON and OFF cycles.

NOTE: Theft deterrent module failure is extremely unlikely. Ensure all circuits are okay before replacing theft deterrent module.

Turn ignition switch to ON position. Observe check engine light. If CHECK ENGINE light is on steady, go to next step. If CHECK ENGINE light is not on steady, repair as necessary. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
Turn ignition off. Connect scan tool to Data Link Connector (DLC). See Fig 1. Using scan tool, establish communication with Engine Control Module (ECM). See scan tool manufacturer's instructions. If scan tool displays ECM data, go to next step. If scan tool does not display ECM data, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
Place transmission in Park (A/T) or Neutral (M/T) and apply parking brake. Start engine. If engine starts, go to next step. If engine does not start, go to step 8.
Using scan tool, select IMMOBILIZER. See scan tool manufacturer's instructions. Turn ignition switch to ON position. Using scan tool, establish communication with theft deterrent module. If scan tool displays immobilizer data, go to next step. If scan tool does not display immobilizer data, see TEST 1: SCAN TOOL DOES NOT COMMUNICATE WITH TDM under SYMPTOM TESTS.
Using scan tool, select DTC information. If any theft deterrent module DTCs are set, see DIAGNOSTIC AIDS in appropriate DTC test and repair accordingly. See DIAGNOSTIC TROUBLE CODE INDEX table. If no theft deterrent module DTCs are set, go to next step.
Check for theft deterrent module history or intermittent DTCs. If history or intermittent DTCs are set, problem is intermittent. Go to description relating to that DTC. If no intermittent DTCs are set, go to next step.
Start engine. If engine starts, system is okay. If engine does not start, go to next step.
Check fuel system, ignition system and general engine condition. If no problem was found, system is okay. If a problem was found, repair as necessary.

DIAGNOSTIC TROUBLE CODE INDEX

DTC

⁽¹⁾ Description

Transponder Key Problem

Wrong Transponder Key

Immobilizer Not Programmed

No Transponder Key Programmed

Vehicle Speed Sensor (VSS) Voltage Low

Vehicle Speed Sensor (VSS) Voltage High

No Engine Request Received

Malfunction Indicator Light (MIL) Circuit

Theft Deterrent Module Malfunction

⁽¹⁾	Perform appropriate test under DIAGNOSTIC TESTS .

Fig 1: Identifying Data Link Connector (DLC) Terminals

Courtesy of GENERAL MOTORS CORP.