P1115

P1115-GENERAL TEMPERATURE RATIONALITY

Special Tools:










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

Theory of Operation

The General Temperature Rationality looks at the outputs of the three temperature sensors and compare 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 two sensors agree but not the third, the third sensor is declared as irrational. If all three sensors are irrational the General Temperature Sensor Rationality is failed.

- When Monitored:
Engine off time is greater than 480 minutes and the vehicle has been driven for one minute over 35 mph. Ambient temperature is greater than -64° C (-83° F).

- Set Condition:
Once the vehicle is soaked for a calibrated engine off time and then driven over calibrated speed and load conditions for some calibrated time, the Powertrain Control Module (PCM) compares the ambient air, engine coolant and intake air temperature sensor values. If the values of all the three sensors disagree with one another, a general temperature sensor irrationality is declared. Two Trip Fault. Three good trips to turn off the MIL.





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

1. ACTIVE DTC
1. Turn the ignition off.
2. 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).
3. 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.
4. With the scan tool, select View the DTCs.

NOTE: Diagnose any CAN Communication DTCs before continuing.

NOTE: If any ECT, AAT, CMP or CKP sensor DTCs have set along with P1115, diagnose them before continuing.

NOTE: In cold weather, this DTC could be set by a high powered block heater and no repair would be required.

Is the DTC Active or Pending at this time?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. . Intermittent Condition Test

2. TEMPERATURE SENSOR READINGS
1. Turn the ignition off.
2. 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.
3. Turn the ignition on.
4. With the scan tool, compare the AAT, ECT and IAT sensor values.

Are all of the temperature sensor values within a range of 10° C (18° F)?

Yes

- Perform the INTERMITTENT CONDITION diagnostic procedure. . Intermittent Condition Test

No

- Go To 3

3. TEMPERATURE SENSOR
1. Ignition on, engine not running.
2. Disconnect the suspected faulty sensor.
3. Connect a jumper wire between the Sensor Signal circuit and the Sensor ground circuit.
4. With the scan tool, read the voltage of the suspected Sensor.

Did the voltage reading start at 4.8 to 5.0 Volts and decrease to 0 Volts when the jumper wire was installed?

Yes

- Verify that there is good pin to terminal contact in the Sensor and Control Module connectors. If OK, replace the appropriate Temperature Sensor. Engine Coolant Temperature Sensor - Removal or. Removal
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4
NOTE: Remove the jumper wire before continuing.


4. EXCESSIVE RESISTANCE IN THE TEMPERATURE SENSOR SIGNAL CIRCUIT




1. Turn the ignition off.
2. Disconnect the C1 and C2 PCM harness connectors.





3. Disconnect the C4 TIPM 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 the PCM Pinout Box to perform diagnosis.





4. Measure the resistance of the Sensor Signal circuit from the Sensor harness connector to the appropriate terminal of the PCM Pinout Box or the C4 TIPM harness connector.

Is the resistance above 5.0 Ohms?

Yes

- Repair the excessive resistance in the Temperature Sensor Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 5

5. EXCESSIVE RESISTANCE IN THE SENSOR GROUND CIRCUIT








1. Measure the resistance of the Sensor ground circuit from the Sensor harness connector to the PCM Pinout Box or the C4 TIPM harness connector.






Is the resistance above 5.0 Ohms?

Yes

- Repair the excessive resistance in the Sensor ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 6

6. SENSOR SIGNAL CIRCUIT SHORTED TO GROUND




1. Measure the resistance between ground and the Sensor Signal circuit at the Sensor harness connector.










Is the resistance below 100 Ohms?

Yes

- Repair the short to ground in the Sensor Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 7

7. SENSOR SIGNAL CIRCUIT SHORTED TO THE SENSOR GROUND CIRCUIT








1. Measure the resistance between ground and the Sensor Signal circuit at the Sensor harness connector.






Is the resistance below 100 Ohms?

Yes

- Repair the short between the Sensor ground circuit and the Sensor Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 8

8. SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE




1. Turn the ignition on.
2. Measure the voltage on the Sensor Signal circuit at the Sensor harness connector.









Is there any voltage present?

Yes

- Repair the short to voltage in the Sensor Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 9

9. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the related 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 related Sensor and Powertrain Control Module connectors.
4. Perform any Technical Service Bulletins 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 Powertrain Control Module. . Powertrain Control Module - Removal
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.