P0118

P0118-ENGINE COOLANT TEMPERATURE (ECT) SENSOR VOLTAGE TOO HIGH

P0118 - Engine Coolant Temperature (ECT) Sensor Voltage Too High:

WHEN MONITORED
With ignition on and battery voltage greater than 10.4 volts.

SET CONDITION
The circuit voltage to the ECM is above a calibrated threshold for a certain period of time.

POSSIBLE CAUSES
- Coolant temperature sensor
- Intermittent condition
- (K2) Signal circuit open
- (K914) Sensor return circuit open
- (K2) Signal circuit shorted
- ECM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test

1. COOLANT TEMPERATURE SENSOR
Disconnect the coolant temperature sensor harness connector.
Check connectors - Clean/repair as necessary.
Measure the resistance of the coolant temperature sensor.

Q: Is the resistance between 300 and 90k ohms?

YES: Go To 2
NO: Replace the coolant temperature sensor. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

2. INTERMITTENT CONDITION
Reconnect the disconnected coolant temp sensor harness connector.
With the scan tool, erase DTCs.
With the scan tool, read DTCs.

Q: Did the DTC return?

YES: Go To 3
NO: Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure).

3. HIGH RESISTANCE IN CIRCUIT





Turn the ignition off.
Disconnect the ECM harness connector.
Check connectors - Clean/repair as necessary.
Measure the resistance between the (K2) temperature sensor signal and (K914) return circuit at the ECM harness connector with the coolant temp sensor harness connected.

Q: Is the resistance between 300 and 90k ohms?

YES: Go To 6
NO: Go To 4

4. (K2) SIGNAL CIRCUIT OPEN





Disconnect the coolant temperature sensor harness connector.
Measure the resistance of the (K2) coolant temperature sensor signal circuit between the coolant temperature sensor connector and the ECM connector.

Q: Is the resistance less than 10 Ohms?

YES: Go To 5
NO: Repair or replace the open (K2) signal circuit. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

5. (K914) SENSOR RETURN CIRCUIT OPEN






Measure the resistance of the (K914) coolant temperature sensor return circuit between the coolant temperature sensor connector and the ECM connector.

Q: Is the resistance less than 10 Ohms?

YES: Go To 6
NO: Repair or replace the open (K914) sensor return circuit. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

6. (K2) SIGNAL CIRCUIT SHORTED






Measure the resistance of (K2) signal circuit to all other circuits at the ECM harness connector.

Q: Is the resistance more than 100k ohms?

YES: Go To 7
NO: Repair or replace the (K2) coolant temperature sensor signal circuit. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

7. ECM





Reconnect the ECM harness connectors.
Turn the ignition on.
With the scan tool, erase DTCs.
While monitoring with scan tool, use a jumper wire and connect the sensor (K2) signal circuit to the (K914) sensor return circuit at the sensor connector.

Q: Did the DTC P0117 set?

YES: Test Complete.
NO: Replace the ECM. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1