2000 2.5 connoisseur auto cruise control

[webteb]

Hi all. Wonder if anyone can help. Cruise control has packed up completely now and not sure where to go next. Center main switch illuminates ok when pressed, light in dash light illuminates when set button on wheel is pressed but no control over speed. I don't think it's the brake pedal switch as suggested in previous posts as the the dash light goes off correctly when the brakes are applied. No clutch pedal on Auto. I also think the ABS sensor is working correctly as the set button doesn't illuminate the dash light until the prerequisite speed has been reached. Disconnected the vacuum pipe from the vacuum pump to the throttle servo actuator and tested the actuator by sucking on the pipe. The actuator diaphragm moved the throttle ok. My only guess now is the vacuum pump itself. Has anyone else suffered the same problem?

[Moonstone]

Most such faults are related to microswitches, but they would all have the dash light off. One poster here reported a similar problem, with the light on in the dash.
http://forums.mg-rover.org/showthread.php?t=145026
but didn't say how/if it was fixed.

I take it there were no splits in the vacuum pipe?

The system has an ECU (behind the glovebox), so that might need resetting. I don't know if disconnecting the battery would do that (check manual for other potential issues before you do that). There's a procedure for removing the glovebox in the How-to forum (BCU "rattle" problem). Haynes reports the ECU is "a small unit to the left of the fuse panel, secured by two bolts"
http://www.the75andztclub.co.uk/forum/showthread.php?t=102

[webteb]

Thanks Moonstone,
Will have a look at the unit. The only issue I'm aware of with battery disconnect is with the radio codes but I have them safely tucked away. I still suspect the fault may lay with the pump/vacuum side of things as the cruise control went through a period of deterioration (slowly allowing the speed to decay) before packing up altogether. The location of the pump is not easy access so I will try the other bits first.

[biggles]

I know that the previous owner of mine had to repair the cruise control and that according to him either the diaphragm assembly or the pump was replaced (I don't remember which though).

[webteb]

Hi all. Wonder if anyone can help. Cruise control has packed up completely now and not sure where to go next. Center main switch illuminates ok when pressed, light in dash light illuminates when set button on wheel is pressed but no control over speed. I don't think it's the brake pedal switch as suggested in previous posts as the the dash light goes off correctly when the brakes are applied. No clutch pedal on Auto. I also think the ABS sensor is working correctly as the set button doesn't illuminate the dash light until the prerequisite speed has been reached. Disconnected the vacuum pipe from the vacuum pump to the throttle servo actuator and tested the actuator by sucking on the pipe. The actuator diaphragm moved the throttle ok. My only guess now is the vacuum pump itself. Has anyone else suffered the same problem?

Just an update of how this problem has been fixed. There was a break in the vacuum system after all. A sharp piece of a loom tie rap below the vacuum actuator created a tiny hole in the diaphragm. Not enough to stop it moving but enough to prevent it holding a vacuum. End result, 5 cent puncture repair patch, system working, priceless!! http://www.the75andztclub.co.uk/forum/images/smilies/lol.gif
:)

[Kandyman]

Thats great news, well done for fixing it.

Thanks for the update :)