0115

0115 ENGINE COOLANT TEMPERATURE SENSOR SIGNAL VOLTAGE TOO HIGH





For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
With the ignition on.

- Set Condition:
The Engine Coolant Temperature Sensor Signal circuit voltage is above the upper limit.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview

Diagnostic Test

1. DTC IS ACTIVE
Ignition on, engine not running.
With the scan tool, Clear DTCs in the Engine Control Module (ECM).
Monitor the scan tool for at least two minutes.
Cycle the ignition key off and on several times, leaving the ignition on for at least 10 seconds at a time.
Start the engine.
Allow the engine to reach normal operating temperature.
With the scan tool, select View DTCs.
Is the status Active for this DTC?

Yes

- Go To 2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Component Tests and General Diagnostics

2. ENGINE COOLANT TEMPERATURE SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE
Turn the ignition off.
Disconnect the Engine Coolant Temperature Sensor harness connector.
Disconnect the Engine Control Module (ECM) harness connector.
Remove the ASD Relay.
Connect a jumper wire between cavity 30 and cavity 87 of the ASD Relay connector.
Turn the ignition on.
Measure the voltage of the Engine Coolant Temperature Sensor Signal circuit in the Engine Coolant Temperature Sensor harness connector.
Is there any voltage present?

Yes

- Repair the Engine Coolant Temperature Sensor Signal circuit for a short to voltage.
- Perform the ECM Verification Test Ver. 1.Verification Tests

No

- Go to 3

3. ENGINE COOLANT TEMPERATURE SENSOR GROUND CIRCUIT SHORTED TO VOLTAGE
NOTE: The jumper wire should still be in place.

Measure the voltage of the Engine Coolant Temperature Sensor Ground circuit in the Engine Coolant Temperature Sensor harness connector.
Is there any voltage present?

Yes

- Repair the Engine Coolant Temperature Sensor Ground circuit for a short to voltage.
- Perform the ECM Verification Test Ver. 1.Verification Tests

No

- Go to 4

4. ENGINE COOLANT TEMPERATURE SENSOR
Turn the ignition off.
Remove the jumper wire and install the ASD Relay.
Connect the Engine Control Module (ECM) harness connector.
Connect a jumper wire between the Engine Coolant Temperature Sensor Ground circuit and the Engine Coolant Temperature Sensor Signal circuit in the Engine Coolant Temperature Sensor harness connector.
Turn the ignition on.
With the scan tool, Clear DTCs.
With the scan tool, select View DTCs.

NOTE: The scan tool should display a Engine Coolant Temperature Sensor low voltage or short to ground DTC with the jumper wire in place.

Does the scan tool display the DTC(s) as described above?

Yes

- Replace the Engine Coolant Temperature Sensor.
- Perform the ECM Verification Test Ver. 1.Verification Tests

No

- Go to 5

5. ENGINE COOLANT TEMPERATURE SENSOR SIGNAL OPEN OR HIGH RESISTANCE
Turn the ignition off.
Disconnect the Engine Control Module (ECM) harness connector.
Measure the resistance of the Engine Coolant Temperature Sensor Signal circuit between the Engine Coolant Temperature Sensor harness connector and the Engine Control Module (ECM) harness connector.
Is the resistance below 10.0 ohms?

Yes

- Go to 6

No

- Repair the Engine Coolant Temperature Sensor Signal circuit for an open circuit or high resistance.
- Perform the ECM Verification Test Ver. 1.Verification Tests

6. ENGINE COOLANT TEMPERATURE SENSOR GROUND CIRCUIT OPEN OR HIGH RESISTANCE
Measure the resistance of the Engine Coolant Temperature Sensor Ground circuit between the Engine Coolant Temperature Sensor harness connector and the Engine Control Module (ECM) harness connector.
Is the resistance below 10.0 ohms?

Yes

- Go to 7

No

- Repair the Engine Coolant Temperature Sensor Ground circuit for an open circuit or high resistance.
- Perform the ECM Verification Test Ver. 1.Verification Tests

7. ENGINE CONTROL MODULE (ECM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Engine Coolant Temperature Sensor and the Engine Control Module (ECM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
Look for the data to change or for the DTC to reset during the wiggle test.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes

- Repair as necessary.
- Perform the ECM Verification Test Ver. 1.Verification Tests

No

- Replace the Engine Control Module (ECM).
- Perform the ECM Verification Test Ver. 1.Verification Tests