Charge Air Cooler Temperature Sensor Circuit Intermittent/Erratic

P007E-CHARGE AIR COOLER TEMPERATURE SENSOR CIRCUIT INTERMITTENT/ERRATIC





For complete wiring diagrams refer to Diagrams/Electrical.

The ambient air temperature sensor are used by the electronic control module (ECM) to monitor the CAC temperature. The ambient air temperature sensor is a thermistor and changes resistance based on the temperature being measured. The ECM provides a 5-volt reference voltage to the sensor. The ECM monitors the change in signal voltage and converts this to a temperature value. There are two parts to this fault code, a key on check and a rationality check. After an 8 hour cold soak, at key ON the readings for the CAC temperature, battery temperature and CAC temperature and coolant temperature are all compared. If the temperatures differ more than a calibrated amount, then the appropriate sensor fault code would be recorded. The key on monitor is disabled for ambient temperatures below 20° F. This monitor looks for all the sensors to be grouped on one temperature or, in the case that the monitor fails, three sensors grouped at one temperature and one outlier. In the case that all four sensor values are distributed over a range of temperatures this diagnostic will not run. A block heater is one possible cause of such a distribution. The rationality check is referred to as a dither. The dither looks at the temperature reading from the sensor over time and ensures that it changes. This monitor is used to detect a "stuck" sensor. If the sensor reading does not change over a calibrated time limit, the fault will be recorded. Both the key-on and dither portions of this rationality error require that the diagnostic fails in two consecutive drive cycles before the MIL lamp is lit. During this time the ECM uses an default value for the ambient air temperature. The ECM turns off the MIL lamp when the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:

Key on engine off and while engine is running.

- Set Condition:

At key on engine off, the CAC temperature sensor reads differently than the battery temperature and ambient air temperature sensors. Or while the engine is running the ECM does not read a change in value from the CAC temperature sensor over time.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test


1. CAC TEMPERATURE SENSOR

Remove the temperature sensor and reconnect the wiring to the sensor.

With the scan tool in Sensors, Monitor the CAC Temperature.

While heating the sensor with an external heat source (DO NOT USE OPEN FLAME).

Does the reading from the sensor increase at least -15° C (5° F) on the scan tool?

Yes

- Go To 2

No

- Replace the CAC temperature sensor.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

2. CAC TEMPERATURE SENSOR

After an 8 hour cold soak, hook up scan tool and monitor CAC temperature, battery temperature, CAC temperature and coolant temperature.


NOTE: Ensure ambient air temperature is above -6.7° C (20° F) when performing this test.


NOTE: Ensure there is no external heat source, such as a block heater, operating during this test or within the 8 hour cold soak.

Does the CAC temperature sensor read differently from the other sensors?

Yes

- Replace the CAC temperature sensor.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition