Conditions

+54 Is Missing

Fault symptoms
The ventilation fan and electrically heated rear window cannot start until 20 s after the engine has started.

Diagnostic help
Ignition +54 can be read in DICE using the diagnostic tool.
If +54 is missing when +15 is present, the bus message Ignition +54 ON is set after 20 s.

The ACC uses the bus message Ignition +54 to disconnect the ventilation fan when the engine is being started.





Diagnostic procedure

1. Checking the programming
^ Check the user programming for the ventilation fan in the ACC.

Is fan delay programmed?
YES
^ Reset programme.
^ Go to step 4.
NO
^ Go to step 2.





2. Checking +54 supply
^ Turn the ignition key to ON





^ Contact: DICE
^ Read value: Ignition +54.
^ Value should be: ON

Is the function correct?
YES
^ Go to step 3.
NO
^ Rectify lead between pin 31 on the control module and crimp connector 140.
^ Go to step 4.





3. Checking +54 supply, (cont.)
^ Turn the ignition key to OFF.
^ Read value: Ignition +54.
^ value should be: OFF.

Is the function correct?
YES
^ Function operating correctly.
^ Go to step 4.
NO
^ Rectify short circuit to B+ in lead between pin 31 on the control module and crimp connector 140.
^ Go to step 4.





4. Final check
^ Delete diagnostic trouble codes in all systems.
^ Carry out a function check.

Is the function correct?
YES
^ The steps taken to rectify the fault were correct.
NO
^ Before Changing a Control Module