Cruise Control Diode

[RodHep]

Just wondering if anyone can help with my cruise control problem. Its the usual story as many threads indicate. Press the on switch on the MF Steering Wheel. I get two flashing green lights and the cruise control does not activate. My Peak tool says its the clutch switch/circuit and I have checked the prox switch (aka clutch switch) on top of the clutch pedal. It works as expected after removal and bench testing. So it seems there is a problem in the wiring. I see 12 volts continuously both on the input 12 Volt supply and also on the output side irrespective of the clutch position. So 12 volts is on the output side from some source. It seem there is a diode which is somewhere between the brake circuit and the clutch switch. I cannot find a wiring diagram that shows the diode in the clutch circuit anywhere. Does anyone know the physical location of this diode? If the diode failed shorted then this would allow 12 volt into the output of the clutch prox switch. This is an unusual fail condition but possible. Other than the diode does anyone have anything further to add to the current knowledge. My car is a 2002 R50 of Australian origin so it has the twin gauges behind the steering wheel and is of course RH drive and is not OBD2 compliant "grrrrr!" Any help would be much appreciated.

[Cooper S Jon]

you should obd compliant on an 02...

[RodHep]

In Australia there was no requirement to be OBD2 compliant until 05 thus these cars are something else again. The only tool I have found that can read the Bus is the Peak Research Scan tool R5/FCX-3-16.

[RodHep]

Activating the Cruise control is done by getting to 60K plus then press the lower left hand button on the Steering wheel. Now its on and the indicator light turns on in the speedo panel. If the ECU detects a clutch movement or a brake pedal movement it disconnects and the throttle is returned to the accelerator pedal. The clutch switch is in the circuit to prevent an over rev situation should the clutch be disengaged. This car has a 6 speed manual tx.

[Cooper S Jon]

your car was built here in the uk,here obd2 compliant was 2001..

the switches on the clutch and brake are there to disengage the cc if they are pressed..

[RodHep]

This car is definitely not OBD2 compliant. OBD2spy cannot decipher the bus language. The only data it supplies is the voltage and my multimeter can do that. The same software however works fine with my Hyundai 2007 which is OBD2 compliant.

[XRV848]

According to the wiring diagram, the clutch switch assembly contains electronics (it's a symbol on the diagram, no indication of what the electronics are). The switch should have three wires connected to it (assuming yours is the same as the euro spec, USA spec has an additional wire). Violet/gray (pin 3) is the power, blue/brown (2) is the connection to the cruise control module and brown (1) connects to ground (earth) at a connection in the panel below the left door.
The switch should connect pin2 to ground when the clutch pedal is depressed, so if you are seeing 12V on pin1 with the switch connected and the pedal down then there is no ground connection.

[RodHep]

thanks for that. I thought the same but i checked the earth pin on the connector and it is showing ground zero compared to the chassis ground. Not sure if the two grounds are at the same potential. I tried to follow the wiring harness but it wanders up to the back of the steering column and without pulling the panel and steering column out its impossible to see every centimetre of the cable. On Nth American someone mentioned a similar problem and the fix was to replace a diode which is an updated BMW mod for the CC. I just cant find the mod details in any documents off line or online....