Checking the On Function

Conditions for ON
The following conditions must be fulfilled before activation of the ON function in the Cruise Control system's control module will be possible:
ON:
Pin A (1): approx. 12 V
Pin B (2): 0 V
Pin C (3): 0 V

The switch should be in the ON position.

1 Connect the BOB and check that about 12 V is present on terminal A (1) of the Cruise Control connector and that no voltage (0 V) is present on terminals B (2) and C (3) when the Switch is in the ON position.
Measure the voltage across the pins and a good ground.





2 If the voltage readings are not OK, check that about 12 V is present across pin 4 of the switch connector and a good ground.
If the voltage is OK, continue with point 4.
3 If no voltage is present, check the wiring for continuity or a short circuit by measuring the resistance across the load side of the fuse and pin 4 of the switch connector.
If the resistance is > 1 ohm, rectify the fault.
4 Check the switch by setting it in the ON position and measuring the resistance across pins 4 and 1. Hold the switch in the RESUME position and measure the resistance across pins 4 and 3. Press the SET button and measure the resistance across pins 4 and 2.
If the resistance reading obtained in any measurement is > 1 ohm, install a new switch.







5 If the resistance is ≤ 1 ohm, check the wiring for continuity or a short circuit by measuring the resistance across:
- pin 2 of the switch connector and pin B of the Cruise Control connector.
- pin 3 of the switch connector and pin C of the Cruise Control connector.
- pin 1 of the switch connector and pin A of the Cruise Control connector.
If the resistance is > 1 ohm, rectify the fault.
6 If no fault has been found after carrying out the above checks, continue fault diagnosis as described "Before Control Module Replacement".