1223 - Coolant Temperature Sensor

NOTE: Perform this test only if MCU code 1223 was retrieved from Digital Motor Electronic (DME) memory.

Engine Management:

1. With the ignition switch in the OFF position, disconnect the coolant temperature sensor connector.
2. Turn the ignition switch to the run position and make the following voltage measurements at the connector (female half).

^ Brown/red wire (terminal 1) and ground = approx. 5 volts.

If not check wire to terminal 78 of the DME control unit harness connector for an open or short to voltage or ground. If wire is OK, the DME control unit is defective.

^ Brown/red (terminal 1) and brown/black (terminal 2) = approx. 5 volts. If not, check wire to ground for an open.
^ If all voltages are correct, continue with step 3.


3. With the ignition switch in the OFF position, clear the DME control unit memory by disconnecting the DME control unit harness connector. Reconnect the control unit harness connector.
4. Install a new coolant temperature sensor.
5. Start the engine and warm it up to normal operating temperature, varying the load conditions.

^ If the check engine light remains off, retain the new coolant temperature sensor. End of test.
^ If the "Check Engine" light illuminates, repeat the self diagnostic procedures in "EXTRACTING FAULT CODES".
^ If a code 1223 reoccurs the DME control unit is defective.