P1115
P1115 - General Temperature Rationality
For wiring diagrams, refer to.
Theory of Operation
The PCM compares engine coolant temperature, intake air temperature, and ambient air temperature under cold start conditions. Following a start to run delay time, the sensor values are compared. If the sensor values are not within a specific range, the values are determined to be irrational.
• When Monitored: With vehicle speed more than 56 kph (35 mph) for more than one minute, ambient temperature more than -64 °C (-83 °F), following an engine off period of more than 480 minutes.
• Set Condition: The PCM compares engine coolant temperature, intake air temperature, and ambient air temperature. If none of the sensor values are within an expected range of each other, a general temperature rationality error is declared. Two trip fault. Three good trips to turn off the MIL.
• Always perform the pre-diagnostic troubleshooting procedure before proceeding. Refer to => Non-DTC Based Diagnostics. Pre-Diagnostic Troubleshooting Procedure
Test Step 1 - DTC is Active
• Diagnose and repair any CAN - C communication or message DTCs in any module before continuing with this procedure.
• Turn the ignition ON.
• With the scan tool, select view DTCs and review the DTC environmental data for this DTC.
Is the good trip counter greater than 0?
Yes
• Go to Test Step 2 => [ Test
Step 2 - Ambient Air Temperature ]
No
• Go to Test Step 3 => [ Test
Step 3 - Temperature Sensor Voltage ]
Test Step 2 - Ambient Air Temperature
• Turn the ignition OFF.
• Allow the vehicle to sit with the ignition off in an environment where the temperature is consistent and more than -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.
Are all of the temperature sensor values within a range of 10 °C (18 °F)?
Yes
• Refer to the checking for an intermittent DTC diagnostic procedure. Refer to => Non-DTC Based Diagnostics. Checking for an Intermittent DTC
No
• Go to Test Step 3 => [ Test
Step 3 - Temperature Sensor Voltage ]
Test Step 3 - Temperature Sensor Voltage
• Turn the ignition OFF.
• Disconnect the harness connector for the temperature sensor that was not within the specified range.
• Turn the ignition ON.
• With a scan tool, read the sensor voltage.
• 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 more than?
Yes
• Go to Test Step 4 => [ Test
Step 4 - Temperature Sensor ]
No
• Go to Test Step 5 => [ Test
Step 5 - Temperature Sensor Signal Circuit Short to Ground ]
Test Step 4 - Temperature Sensor
• Turn the ignition OFF.
• Connect a jumper wire between the sensor signal circuit and the sensor ground circuit in the temperature sensor harness connector.
• Turn the ignition ON.
• With a scan tool, read the sensor voltage.
• 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 more than?
Yes
• Replace the temperature sensor.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
No
• Go to Test Step 5 => [ Test
Step 5 - Temperature Sensor Signal Circuit Short to Ground ]
Test Step 5 - Temperature Sensor Signal Circuit Short to Ground
• Turn the ignition OFF.
• Disconnect the appropriate control module harness connector. Refer to the mini schematic for circuit identification.
• Measure the resistance between ground and the temperature sensor signal circuit in the temperature sensor harness connector.
Is the resistance less than 100 ohms?
Yes
• Repair the temperature sensor signal circuit for a short to ground.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
No
• Go to Test Step 6 => [ Test
Step 6 - Temperature Sensor Signal Circuit Short to Voltage ]
Test Step 6 - Temperature Sensor Signal Circuit Short to Voltage
• Turn the ignition ON.
• Measure the voltage of the temperature sensor signal circuit in the temperature sensor harness connector.
Is there any voltage present?
Yes
• Repair the temperature sensor signal circuit for a short to voltage.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
No
• Go to Test Step 7 => [ Test
Step 7 - Temperature Sensor Signal Circuit Open or High Resistance ]
Test Step 7 - Temperature Sensor Signal Circuit Open or High Resistance
• Turn the ignition OFF.
• Measure the resistance of the temperature sensor signal circuit between the temperature sensor and the applicable control module.
Is the resistance less than 5 ohms?
Yes
• Go to Test Step 8 => [ Test
Step 8 - Temperature Sensor Ground Circuit Open or High Resistance ]
No
• Repair the temperature sensor signal circuit for an open or high resistance.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
Test Step 8 - Temperature Sensor Ground Circuit Open or High Resistance
• Measure the resistance of the temperature sensor ground circuit between the temperature sensor and the applicable control module.
Is the resistance less than 5 ohms?
Yes
• Go to Test Step 9 => [ Test
Step 9 - PCM ]
No
• Repair the temperature sensor ground circuit for high resistance.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
Test Step 9 - PCM
• Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the temperature sensor and the PCM.
• 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.
• Refer to any technical service bulletins that may apply.
Were any problems found?
Yes
• Repair as necessary.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
No
• Replace the PCM.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test