Without ETS

DIAGNOSTIC TROUBLE CODES P0115, P0117, P0118 (cars without ETS)
Engine coolant temperature sensor, malfunctioning or not working at all

Fault symptom
The CHECK ENGINE lamp (MIL) is on.
Poorer engine performance.
Difficult to start engine from cold.


Conditions.
If there is a short circuit/open circuit, a DTC will be generated after 5 seconds.

DIAGNOSTIC PROCEDURE

1. Checking the operation of the temperature sensor
Connect the Scan Tool.
Ignition switch in the ON position.
Select "READ FUNCTIONS"
Select "COOLANT TEMPERATURE".
The Scan Tool shows the prevailing engine temperature.

NOTE: In the event of a temperature sensor fault, the control module will assume the default value of 26°C. This is the figure that the Scan Tool will display in such cases.

If the reading is OK, continue with point 4.

If the reading is not OK, continue with point 2.






2. Checking the electrical interfaces of the temperature sensor
Turn the ignition switch to the ON position and then back to the OFF position.
Unplug the temperature sensor's 2-pin connector.
Take voltage readings at the connector across:
- Pin 2 and battery negative about 5 V
- Battery positive and pin 1 about 12 V.

Check the control module's temperature input for continuity.
- Select "READ FUNCTIONS".
- Select "COOLANT TEMPERATURE".

The Scan Tool should show a reading of about -40°C.
Connect a jumper lead across pins 1 and 2 of the temperature sensor connector.
The Scan Tool should show a reading of about +125°C.
The above tests show whether the control module and wiring as far as the temperature sensor are in good working order.

If all readings are OK, change the temperature sensor.

If any reading is not OK, continue with point 3.





3. Checking the wiring harness
Check The Wiring between the control module and the temperature sensor's 2-pin connector for continuity.
Check The Wiring for continuity, shorting and any stray currents.

If the wiring is OK, continue with point 4.

If any lead is not OK, rectify the fault.

4. Final Check
Clear the diagnostic trouble code, drive the car on test and check whether the trouble code is generated afresh.

If the DTC is generated again, refer to Before Replacing A Control Module.

If the DTC is not generated again and is not recorded, the action taken to rectify the fault was correct, otherwise the fault is of intermittent nature.