P0116

P0116-ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT PERFORMANCE





For a complete wiring diagram refer to Diagrams/Electrical.


Theory of Operation


Engine Coolant Temperature Sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. Following a start to run delay time, the outputs of the ambient, engine coolant, and intake air temperature sensors will be compared. If the intake air and ambient air temperature sensors agree and the intake air temperature does not agree, the intake air temperature sensor is declared as irrational.

- When Monitored:

Engine off time is greater than 480 minutes. Ambient temperature is greater than 4° C (38° F).

- Set Condition:

After a calibrated amount of cool down time the PCM compares the ECT Sensor, IAT Sensor, and the Ambient Air Temp Sensor values. If the IAT Sensor value is not within 10° C (18° F) of the other two temperature sensors. Two Trip Fault. Three good trips to turn off the MIL.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.


Diagnostic Test


1. ACTIVE DTC


NOTE: Diagnose any CAN - C Communication DTCs before continuing.

Turn the ignition off.

If possible, allow the vehicle to sit with the ignition off for more than 480 minutes in an environment where the temperature is consistent and above - 7° C (19.4° F).

Test drive the vehicle. The vehicle must exceed 48 km/h (30 mph) during the test drive. Do not cycle the ignition off when the test drive is completed.

With a scan tool, select View DTCs.

Is the DTC Active or Pending at this time?

Yes

- Go To 3

No

- Go To 2


2. ENGINE COOLANT TEMPERATURE

Turn the ignition off.

Allow the vehicle to sit with the ignition off in an environment where the temperature is consistent and above - 7° C (19.4° F) until the engine coolant temperature is equal to ambient temperature.

Turn the ignition on.

With a scan tool, compare the AAT, ECT, and IAT sensor values.

Is the Engine Coolant Temperature Sensor value within 10° C (18° F) of the other two sensor values?

Yes

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition

No

- Go To 3


3. ECT SENSOR VOLTAGE

Turn the ignition off.

Disconnect the Engine Coolant Temperature Sensor harness connector.

Turn the ignition on.

With a scan tool, read the Engine Coolant Temperature Sensor voltage.


NOTE: The sensor voltage should be approximately 5.0 volts (plus or minus .1 volt) with the connector disconnected.

Does the scan tool display the voltage as described above?

Yes

- Go To 4

No

- Go To 5


4. ECT SENSOR





Turn the ignition off.

Connect a jumper wire between the (K2) ECT Signal circuit and the (K900) Sensor Ground circuit in the Engine Coolant Temperature Sensor harness connector.

Turn the ignition on.

With a scan tool, read the Engine Coolant Temperature Sensor voltage.


NOTE: The sensor voltage should be approximately 0.0 volts (plus or minus .1 volt) with the jumper wire in place.

Does the scan tool display the voltage as described above?

Yes

- Replace the ECT Sensor.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 5

NOTE: Remove the jumper wire before continuing.


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

Turn the ignition off.

Disconnect the C2 PCM harness connector.


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 and #8815-1 to perform diagnosis.

Using a voltmeter perform a voltage drop test. Backprobe the (K2) ECT Signal circuit at the ECT Sensor harness connector and probe the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so a positive polarity is displayed on the voltmeter.


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 can result in personal injury or death.

Start the engine and allow it to reach normal operating temperature.

Monitor the voltmeter.

Is the voltage below 0.5 of a volt?

Yes

- Go To 6

No

- Repair the open in the (K2) ECT Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


6. EXCESSIVE RESISTANCE IN THE (K900) SENSOR GROUND CIRCUIT

Turn the ignition off.

Move the voltmeter leads to backprobe the (K900) Sensor Ground circuit at the ECT Sensor harness connector and to probe the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so a positive polarity is indicated on the voltmeter.


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 can result in personal injury or death.

Start the engine and allow it to reach normal operating temperature.

Monitor the voltmeter.

Is the voltage below 0.5 volts?

Yes

- Go To 7

No

- Repair the open in the (K900) Sensor ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


7. 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 the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

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