Automatic Climate Control, ACC

B1350





Cabin temperature sensor. Short to ground
Cabin temperature sensor. Open circuit/short to B+

Fault symptoms
Perceived temperature in cabin too high or too low compared to the set temperature.

Conditions
The following conditions apply:
- Open circuit or short to B+ on pin 20 >4.9 V.
- Short to ground on pin 20<0.1 V.
- Measured every 440 ms and 5 consecutive measurements are required to set a diagnostic trouble code.
- The diagnostic trouble code is deleted after the ignition has been switched on 20 times if the fault conditions have not been fulfilled.
- When the diagnostic trouble code is set, the control module uses a default value. When the ignition is turned on, the outside temperature is used as a default value and after that, a mean value of the calculated temperatures at head height for the front seat passenger and the driver is used.





Diagnostic procedure

1. Checking the diagnostic trouble code
- Contact the ACC.

Is diagnostic trouble code B2945 displayed on the diagnostics tool?
YES
- Go to diagnostic trouble code B2945.
NO
- Go to step 2.





2. Checking the sensor's ground connection
- Unplug connector: Temperature sensor, cabin air: (218).





- Connect a test lamp between B+ and pin 3 (yellow/white lead) on the female connector. Note that the connector has two poles but that the pins are marked 2 and 3.





- The test lamp should light.

Is the function correct?
YES
- Go to step 3.
NO
- Rectify lead in question.
- Go to step 5.





3. Checking the control module temperature sensor input, open circuit
- Turn the ignition key to ON





- Contact the ACC.
- Read voltage: Cabin Temperature Sensor.
- Value should be 4.7-5.0 V.

Is the function correct?
YES
- Go to step 4.
NO
- Rectify lead in question.
- Go to step 5.





4. Checking the control module temperature sensor input, connector with jumper
- Connect a jumper wire between pins 2 and 3 on the female connector. Note that the connector has two poles but that the pins are marked 2 and 3.
- Read voltage: Cabin Temperature Sensor.
- Value should be 0 V.

Is the function correct?
YES
- Replace : Temperature sensor, cabin air.
- Go to step 5.
NO
- Rectify lead in question.
- Go to step 5.





5. Final check
- Delete diagnostic trouble codes in all systems.





- Carry out a function check.
- Evaluate the function check.
- Check that the diagnostic trouble code does not recur.

Does the diagnostic trouble code recur?
YES
- See "Before changing a control module." Before Changing a Control Module

NO
- The steps taken to rectify the fault were correct.