P0118

P0118-ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT HIGH






For a complete wiring diagram refer to: Electrical Diagrams

When Monitored
With the ignition on. Battery voltage greater than 10.4 volts.

Set Condition
The Engine Coolant Temperature (ECT) sensor circuit voltage at the PCM is greater than 4.98 volts for more than 2.8 seconds. One Trip Fault. Three good trips to turn off the MIL. (ETC lamp will illuminate with the MIL.)

Possible Causes
- (K2) ECT SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
- (K2) ECT SIGNAL CIRCUIT OPEN
- (K900) SENSOR GROUND CIRCUIT OPEN
- ECT SENSOR
- PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test
1. ECT SENSOR VOLTAGE ABOVE 4.98 VOLTS





Ignition on, engine not running.
With a scan tool, read the ECT voltage.

Is the voltage above 4.98 volts?
Yes >> Go To 2
No >> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

2. ECT SENSOR





Turn the ignition off.
Disconnect the ECT harness connector.
Connect a jumper wire between the (K2) ECT Signal circuit and the (K900) Sensor ground circuit in the ECT harness connector.
Ignition on, engine not running.
With a scan tool, read ECT voltage.

Is the voltage below 1.0 volt with the jumper wire installed?
Yes >> Replace the ECT Sensor.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 3

NOTE: Remove the jumper wire before continuing.

3. (K2) ECT SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE





Turn the ignition off.
Disconnect the PCM harness connectors.
Ignition on, engine not running.
Measure the voltage on the (K2) ECT Signal circuit in the ECT Sensor harness connector.

Is voltage present?
Yes >> Repair the short to battery voltage in the (K2) ECT Signal circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 4

4. (K2) ECT SIGNAL CIRCUIT OPEN





Turn the ignition off.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

Measure the resistance of the (K2) ECT Signal circuit from the ECT Sensor harness connector to the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?
Yes >> Go To 5
No >> Repair the open in the (K2) ECT Signal circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

5. (K900) SENSOR GROUND CIRCUIT OPEN





Measure the resistance of the (K900) Sensor ground circuit from the ECT Sensor harness connector to the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?
Yes >> Go To 6
No >> Repair the open in the (K900) Sensor ground circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

6. PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

Were there any problems found?
Yes >> Repair as necessary
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Replace and program the Powertrain Control Module per Service Information.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test