P0117

P0117-ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT LOW





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams.

Theory of Operation

The Engine Coolant Temperature (ECT) sensor is a negative temperature coefficient thermistor-type sensor. The resistance varies inversely with temperature. At cold temperatures the sensor resistance and voltage is high. As the coolant temperature increases, the resistance decreases and the voltage becomes low.

- When Monitored:
With the ignition on. The battery voltage greater than 10.4 Volts.

- Set Condition:
The Powertrain Control Module (PCM) detects that the Engine Coolant Temperature (ECT) sensor input voltage is below the minimum acceptable value, One Trip Fault. Three good trips to clear the Malfunction Indicator Lamp (MIL). The MIL and ETC light illuminates if equipped.





WARNING: On vehicles equipped with the high voltage system, you must thoroughly read and follow all High Voltage Safety procedures. In addition, before performing any diagnostic or service procedure near a high voltage component, you must perform the High Voltage Power Down. Failure to follow these instructions may result in possible serious or fatal injury

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC
1. Start the engine and allow it to reach normal 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 clothing. Failure to follow these instructions may result in possible serious or fatal injury.

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

2. With the scan tool, select View DTCs.

Is the DTC active at this time?

Yes

- Go To 2

No

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition Test.

2. ECT SENSOR
1. Turn the ignition off.
2. Disconnect the ECT harness connector.
3. Ignition on, engine not running.
4. With the scan tool, read ECT voltage.

NOTE: The sensor voltage should be approximately 5.0 Volts (+/- 0.1 Volts) with the electrical connector disconnected.

Does the scan tool display the voltage as described above?

Yes

- Verify that there is good pin to terminal contact in the ECT sensor and PCM connectors. Replace the ECT sensor if no problems were found in the electrical connectors.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3

3. (K2) ECT SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUND CIRCUIT




1. Turn the ignition off.
2. Disconnect the C2 PCM harness connector.
3. Measure the resistance between the (K900) sensor ground circuit and the (K2) ECT signal circuit in the ECT sensor harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Repair the short to between the (K900) sensor ground circuit and the (K2) ECT signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. (K2) ECT SIGNAL CIRCUIT SHORTED GROUND




1. Measure the resistance between ground and the (K2) ECT signal circuit in the ECT sensor harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short to ground in the (K2) ECT signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 5

5. EXCESSIVE RESISTANCE IN THE (K2) ECT SIGNAL CIRCUIT





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 PCM Pinout Box 8815 to perform diagnosis.

1. Measure the resistance of the (K2) ECT signal circuit between the ECT sensor harness connector and the appropriate terminal of special tool #8815.

Is the resistance below 5.0 Ohms?

Yes

- Go To 6

No

- Repair the excessive resistance in the (K2) ECT signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

6. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and electrical connectors between the ECT sensor and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the ECT sensor and PCM connectors.
4. Search for any Technical Service Bulletins (TSBs) that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the PCM.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.