Check for continuity between ECM/PCM connector terminal A20 and body ground. ECM/PCM CONNECTOR A (31P) Wire side of female terminals Is there continuity? YES - Repair short in the wire between the ECM/PCM (A20) and the EGR valve position sensor, knock sensor or TP sensor, or repair short in the wire between ECM/PCM (A8) and the knock sensor. NO - Substitute a known-good ECM/PCM and recheck. If symptom/indication goes away, replace the original ECM/PCM.

Measure voltage between body ground and ECM/PCM connector terminals E5. ECM/PCM CONNECTOR E (31P) Wire side of female terminals Is there about 5 V? YES - Substitute a known-good ECM/PCM and recheck. If the symptom/indication goes away, replace the original ECM/PCM. NO - Go to step 63. Turn the ignition switch OFF. Disconnect the idle mixture adjuster (IMA) 3P connector. Turn the ignition switch ON (II).