Idling speed adjustment
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 INC: 0.7-0.9 V (60 ohm)STO: 1.6-1.7 V (154 ohm)DEC: 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 idle adjustment switch module has been either above or below the permitted level.For each function in the switch module (ON, OFF, INC, STO and DEC) a unique voltage value is sent to the coordinator when activated. The fault code is set if the voltage between coordinator pin 29 and 48 has been implausible in relation to the function which is activated.
Short circuit or open circuit in the idle adjustment switch module circuit. There may also be an internal fault in the switch module or in exceptional cases in the coordinator.