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Malfunction Indicator Light Check

NOTE: When ECM memory is cleared, battery voltage is disconnected or ECM is disconnected it is necessary to generate a ECM readiness code. See READINESS CODE  under SELF-DIAGNOSTIC SYSTEM.
NOTE: Malfunction Indicator Light (MIL) check should only be performed if MIL is on continuously and no DTCs are stored, or MIL never illuminates.
  1. Turn ignition on. If MIL does not illuminate, go to next step. If MIL illuminates, but does not shut off after 3 seconds, go to step  5.
  2. Turn ignition off. Disconnect Engine Control Module (ECM) harness connector. ECM is located in left rear corner of engine compartment, in electronics box. Connect VAG 1598/31 test box to ECM harness connector (leave ECM disconnected). See Figure. Bridge VAG test box sockets No. 2 and 47. Turn ignition on. If MIL does not illuminate, go to next step.
  3. Check MIL bulb in instrument panel. Replace if necessary. Retest system. If bulb is okay, test voltage supply to MIL. For 2002, see WIRING DIAGRAMS article. If problem is found, repair as necessary. If no problem is found, go to next step.
  4. Turn ignition off. Check for open in circuits between ECM and MIL. If problem is found, repair as necessary. If no problem is found, replace ECM. See ENGINE CONTROL MODULE REPLACEMENT  under PROGRAMMING.
  5. Turn ignition off. Disconnect Engine Control Module (ECM) harness connector. ECM is located in left rear corner of engine compartment, in electronics box. Connect VAG 1598/31 test box to ECM harness connector (leave ECM disconnected). See Figure. Using DVOM, measure resistance between ground and VAG test box socket No. 47. Resistance should be infinity. If resistance is as specified, and no other problems are found, go to step  7. If resistance is not as specified, go to next step.
  6. Repair short to ground in circuit between ECM and MIL. After repairs, retest system.
  7. If no problem in wiring was found, replace ECM. See ENGINE CONTROL MODULE REPLACEMENT  under PROGRAMMING.
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