Testing if display approx. 140.0°C

-- Disconnect the Engine Coolant Temperature (ECT) Sensor - G62 or 83- electrical harness connector.

-- Turn the ignition switch ON.

If indication jumps to approx. - 40.0°C:

-- Switch ignition OFF.

-- Replace the Engine Coolant Temperature (ECT) Sensor - G62 or 83-. Refer to the Repair Information.

If the value remains at approx. 140.0°C

Checking wiring 

If the manufacturers test box is being used, perform the following step.

-- Install the test box.

If the manufacturers test box is not being used, perform the following step.

-- Remove the Motronic Engine Control Module (ECM) -J623- and disconnect the ECM connectors. Refer to the Repair Information.

-- Disconnect the ECT harness connector at the sensor.

-- Using a multimeter, check the signal circuit of the Engine Coolant Temperature (ECT) Sensor - G62 or 83- electrical harness connector terminal 1 to engine ground.

Specified value: OL or no continuity.

If the specified value was Not obtained:

-- Check the wiring for a short circuit to Ground.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If the specified value was obtained:

-- Replace the Motronic Engine Control Module (ECM) -J623-. Refer to the Repair Information.