P1115

P1115-GENERAL TEMPERATURE RATIONALITY






For a complete wiring diagram refer to: Electrical Diagrams

When Monitored
Ignition on and battery voltage greater than 10 volts.

Set Condition
Ambient Air, Engine Coolant, and Intake Air Temp sensor inputs are compared under cold start conditions. After start up the temp readings are monitored. If two of the three readings agree and the third doesn't, a DTC is stored. Two Trip Fault. Three good trips to turn off the MIL.

Possible Causes
- EXCESSIVE RESISTANCE IN THE SENSOR SIGNAL CIRCUIT
- EXCESSIVE RESISTANCE IN THE (K900) SENSOR GROUND CIRCUIT
- TEMPERATURE SENSOR
- PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test
1. ACTIVE DTC





Ignition on, engine not running.
With a scan tool, read the DTCs.

NOTE: All ECT, Intake Air, and Ambient Air Temperature Sensor codes must be diagnosed and repaired before continuing.

NOTE: In cold weather, this DTC could be set by a non-OEM approved block heater and no repair would be required.

Is the DTC active at this time?
Yes >> Go To 2
No >> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
2. TEMPERATURE SENSOR CIRCUIT
With a scan tool, read the ECT, Ambient Air Temp, and Intake Air Temp Sensor temp values.
Start the engine.
Allow the engine to reach normal operating temperature while monitoring the three Sensor temperature values.

Is the temperature for each of the Sensors increasing properly?
Yes >> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 3
3. TEMPERATURE SENSOR
Ignition on, engine not running.
Disconnect the suspected faulty sensor.
Connect a jumper wire between the Sensor Signal circuit and the (K900) Sensor ground circuit.
With the scan tool, read the voltage of the suspected Sensor.

NOTE: Remove the jumper wire before continuing.

Did the voltage reading start at 4.8 to 5.0 volts and decrease to 0 volts when the jumper wire was installed?
Yes >> Replace the faulty Sensor.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 4
4. EXCESSIVE RESISTANCE IN THE TEMPERATURE SENSOR SIGNAL CIRCUIT





Turn the ignition off.
Disconnect the PCM harness connectors.

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 to perform diagnosis.

Measure the resistance of the Sensor Signal circuit from the Sensor harness connector to the appropriate terminal of special tool #8815.

Is the resistance above 5.0 ohms.
Yes >> Repair the excessive resistance in the Temperature Sensor Signal circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 5
5. EXCESSIVE RESISTANCE IN THE (K900) SENSOR GROUND CIRCUIT





Measure the resistance of the (K900) Sensor ground circuit from the Sensor harness connector to the appropriate terminal of special tool #8815.

Is the resistance above 5.0 ohms.
Yes >> Repair the excessive resistance in the (K900) Sensor ground circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 6
6. 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 POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Replace and program the Powertrain Control Module per Service Information.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test