STEP 3. 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) Turn on the power supply mode of the electric motor switch.
(3) Measure the voltage between terminal LHFL and ground.- Voltage should be 12V starter battery positive voltage.
(4) Turn off the power supply mode of the electric motor switch.
Is 12V starter battery positive voltage (approximately 12 volts) present?
Go to Step 4. Repair or replace the connector(s), or check and repair the harness of short to ground and open circuit in LHFL line between linear air-fuel ratio sensor connector and ECM connector. Then go to Step 7.