42521/22521

Fault Symptom.
Permanent: 42521
Intermittent: 22521

Conditions
This diagnostic trouble code is generated if the self test program detects 12 V on a general ground cable (0 V cable) for the blended air temperature sensor, pin 22 and cabin temperature sensor, pin 2 together with diagnostic trouble codes 46322 and 46323. Measurement gives less than 12 V. Only one diagnostic trouble code (42521 - 22521).





Sensors, General Ground Faults - Testing.
ISAT scan tool command: 250
Display shows:
Cabin temperature = +10 to +40 °C
If the display shows +18 °C, the fault may be battery positive voltage on pin 2.

ISAT scan tool command: 252
Display shows:
Blended air temperature = 0 to +80 °C
If the display shows +50 °C (version 2.00) or a fixed value calculated by the ACC control module (version 2.01), the fault may be battery positive voltage on pin 22.

NOTE: At temperatures below 0 °C, the cabin temperature sensor and blended air temperature sensor cannot be tested.





Action
1. Allow the ACC control module's 39 pin connector to be connected. Switch on the ignition and measure voltage between pin 2 and ground or pin 22 and ground from the rear if the connector.

2. If there is voltage, switch off the ignition, wait for 35 seconds and unplug the 39 pin connector from the ACC control module.

3. Switch on the ignition. If there is still voltage, check the wiring harness to the sensor and the sensor itself.

4. If no voltage is indicated, refit connectors and erase diagnostic trouble codes. Restart the system to check if the fault is still present before trying a new ACC control module.