P0118

SYMPTOM
P0118-ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT HIGH

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. (5.7L 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. Scan Tool Testing and Procedures

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>> Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5. Powertrain Verification Test - Ver 5

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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.
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 the voltage above 5.2 volts?
Yes>> Repair the short to battery voltage in the (K2) ECT Signal circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.
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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.

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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.

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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.
No>> Replace and program the Powertrain Control Module per Service Information. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.