Testing if display is approx. - 40.0°C
-- Disconnect the Engine Coolant Temperature (ECT) Sensor -G62 - electrical harness connector.
-- Using a jumper wire, connect the Engine Coolant Temperature (ECT) Sensor - G62- electrical harness connector terminals 3 to 4.
-- Start the engine and let it run at idle.
-- Check the value indicated on the scan tool display.
If the value jumps to approx. 140.0 °C:
-- Switch the ignition OFF.
-- Replace the Engine Coolant Temperature (ECT) Sensor -G62 -.
If indication remains at approx. -40.0 °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) -J220-. Refer to the Repair Information.
-- Using a multimeter, check the Engine Coolant Temperature (ECT) Sensor -G62 - electrical harness connector terminals to the Motronic Engine Control Module (ECM) -J220- electrical harness connector for an open circuit or a short to voltage, refer to the chart below.
| Engine Coolant Temperature (ECT) Sensor -G62 - electrical harness connector terminals | Motronic Engine Control Module (ECM) -J220- electrical connector T121 terminals or test box socket |
|---|---|
| 3 | 93 |
| 4 | 108 |
Specified circuit values: 1.5 Ω Max. resistance and 0 volts when disconnected from ECM.
If the specified value was Not obtained:
-- Check the wiring for an open or short circuit to Battery (+).
-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
-- If necessary, repair the faulty wiring connection.
If no malfunction is detected in the signal circuit:
-- Using a multimeter, check terminal 3 of the ECT sensor to engine ground.
Specified value: 1.5 Ω Max
If the specified value was Not obtained:
-- Check the wiring for an open circuit or high resistance.
-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
-- If necessary, repair the faulty wiring connection.
If no malfunction is detected in the ground circuit:
-- Replace the Motronic Engine Control Module (ECM) -J220-. Refer to the Repair Information.