2000 - 2999: 2065

2065-ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT LOW





For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
With the ignition on and battery voltage greater than 10 volts.

- Set Condition:
The PCM detects that the Engine Coolant Temperature Sensor input voltage is below the minimum acceptable value.





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

Diagnostic Test

1. DTC IS ACTIVE

NOTE: Diagnose and repair any system voltage or sensor supply voltage DTCs before continuing with this test.

Turn the ignition on.
With the scan tool, read DTCs.
Record all DTC and applicable Freeze Frame information.
With the scan tool, clear DTCs.
Cycle the ignition off for at least one minute.
Start the engine and allow it to reach operating temperature.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose fitting clothing. Failure to follow these instructions can result in personal or fatal injury.

With the scan tool, read DTCs.
Does this DTC reset?

Yes

- Go to 2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Checking for an Intermittent DTC

2. ENGINE COOLANT TEMPERATURE SENSOR WIRING AND CONNECTORS




Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Engine Coolant Temperature Sensor (1) and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Inspect the Engine Coolant Temperature Sensor for any condition that would result in an incorrect signal, such as damage, corrosion, or contamination.
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test.Powertrain Verification Test.

No

- Go to 3

3. ECT SIGNAL CIRCUIT SHORTED TO GROUND




Turn the ignition off.
Disconnect the Engine Coolant Temperature Sensor connector.
Disconnect the Powertrain Control Module (PCM) connector.
Measure the resistance between ground and the ECT Signal circuit in the Engine Coolant Temperature Sensor harness connector.
Is the resistance above 100 ohms?

Yes

- Go to 4

No

- Repair the ECT Signal circuit for a short to ground.
- Perform the PCM Verification Test.Powertrain Verification Test

4. ECT SIGNAL CIRCUIT SHORTED TO SENSOR GROUND CIRCUIT




Measure the resistance between the ECT Signal circuit and the Sensor Ground circuit in the Engine Coolant Temperature Sensor harness connector.
Is the resistance above 100 ohms?

Yes

- Go to 5

No

- Repair the ECT Signal circuit for a short to the Sensor Ground circuit.
- Perform the PCM Verification Test.Powertrain Verification Test

5. ECT SIGNAL CIRCUIT OPEN CIRCUIT OR HIGH RESISTANCE




Measure the resistance of the ECT Signal circuit between the Engine Coolant Temperature Sensor harness connector and the PCM harness connector.
Is the resistance below 5.0 ohms?

Yes

- Go to 6

No

- Repair the ECT Signal circuit for an open circuit or high resistance.
- Perform the PCM Verification Test.Powertrain Verification Test

6. ENGINE COOLANT TEMPERATURE SENSOR
Turn the ignition off.
Connect the Powertrain Control Module (PCM) connector.
Turn the ignition on.
With the scan tool, read the Engine Coolant Temperature Sensor signal voltage.

NOTE: The sensor voltage should be greater than 4.8 volts with the connector disconnected.

Does the scan tool display the voltage as described above?

Yes

- Replace the Engine Coolant Temperature Sensor.
- Perform the PCM Verification Test.Powertrain Verification Test

No

- Go to 7

7. POWERTRAIN CONTROL MODULE (PCM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Engine Coolant Temperature Sensor and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test.Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module (PCM).
- Perform the PCM Verification Test.Powertrain Verification Test.