STEP 1. Measure the power supply voltage at ECM connector by using power plant ECU check harness special tool MB992110.
(1) Disconnect all ECM connectors. Connect the power plant ECU check harness special tool MB992110 between the separated connectors.
(2) Start the engine and run at idle.
(3) Measure the voltage between terminal OCVP and ground.- Voltage should be 1 volt or less when engine is idling.
- Voltage should be battery positive voltage when engine speed is higher than 5,200 r/min.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the measured voltage normal?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions . Go to Step 2.