Vent Fan Doesn't Start Until 20 Seconds After Engine Is Started

Ventilation Fan Does Not Start Until 20 Seconds After the Engine Has Been Started

Fault symptoms
Ventilation fan does not start until 20 seconds after the engine has been started.

Conditions
+54 from DICE on bus is missing.

Checking the wiring harness
Move the wiring harness at various points and in different direction to detect any intermittent breaks or short circuits. Observe the multimeter, test lamp or diagnostics tool while checking.






Diagnostic procedure

1. Check the programming
- Check user programming in ACC for ventilation fan.

Is fan delay programmed?
YES
- Reset program.
- Go to step 4.
NO
- Go to step 2.






2. Check the +54 power supply
- Turn the ignition switch to the ON position.






- Contact DICE.
- Read value: Ignition +54.
- Value should be: (ON).

Test results OK?
YES
- Go to step 3.
NO
- Rectify the lead between pin 31 on the control module and crimp connection J59.
- Go to step 4.






3. Check the +54 power supply, continued
- Turn the ignition switch to the OFF position
- Read value: Ignition +54.
- Value should be: (OFF).

Test results OK?
YES
- Functionality is OK.
- Go to step 4.
NO
- Rectify short to B+ in the lead between the control module pin 31 and crimp connector J59.
- Go to step 4.






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






- Carry out a function check.

Test results OK?
YES
- The steps taken to rectify the fault were correct.
- See "Before changing a control module."