Ignition "OFF" & Engine "OFF".

Disconnect ECM from vehicle.

Substitute with a known-good ECM and check for proper operation.

Is the problem corrected?

YES

▶ Replace ECM and then go to "Verification of Vehicle Repair" procedure.

NO

▶ Thoroughly check connectors for looseness, poor connection,bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.