Cruise control
Check the switch module, including wiring and connectors.Measure the voltage (or the resistance) between coordinator pin 29 and 48. The values are not to deviate significantly from the below: Cruise control function ACC: 0.7-0.9 V (60 ohm)RES: 1.6-1.7 V (154 ohm)RET: 2.5-2.7 V (333 ohm)ON: 3.3-3.5 (665 ohm)OFF: 3.7-4.3 V (1,596 ohm) Check also whether the engine control unit has generated any fault codes.If this is shown to be an internal fault in the coordinator, the coordinator must be renewed.
What you'll see
No driver-visible symptom recorded.
System reaction
No system-reaction text recorded.
Diagnostic depth
The voltage in the circuit for the cruise control switch module has been either higher or lower than permitted.For each cruise control function (ON, OFF, ACC, RES and RET) a unique voltage value is sent to the coordinator when activated. Fault code is generated if the voltage between coordinator pins 29 and 48 has been implausible in relation to the activated function.
Short circuit or open circuit in the cruise control switch module circuit. There may also be an internal fault in the switch module or in exceptional cases in the coordinator.