MIL Circuit Troubleshooting
  1. Turn the ignition switch ON (II).
Does the MIL indicator flash?
YES -
Go to Step 3 .
NO -
Substitute a known-good gauge control module (tach), and recheck. If the MIL circuit is OK, replace the original gauge control module (tach). ■
  1. Check the SCS in the DATA LIST with the HDS.
Is a short indicated?
YES -
Go to Step 5 .
NO -
Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM. ■
  1. Turn the ignition switch OFF, and wait 2 minutes.
  1. Disconnect the HDS from the DLC.
  1. Check for continuity between ECM connector No. 2 terminal No. 20 and body ground.
Is there continuity?
YES -
Repair short in the wire between the SRS unit, the DLC and ECM connector No. 2 terminal No. 20.■
NO -
Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM. ■