P1115

SYMPTOM
P1115-GENERAL TEMPERATURE RATIONALITY

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. Scan Tool Testing and Procedures

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 high powered block heater and no repair would be required.

Is the DTC active at this time?
Yes>> Go To 2
No>> Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5. Powertrain Verification Test - Ver 5

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>> Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.
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.
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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.
No>> Go To 4
Note: Remove the jumper wire before continuing.

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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.
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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.
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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.
No>> Replace and program the Powertrain Control Module per Service Information. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.