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Cruise control suddenly working intermittently

Dr W

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Yet another problem on the old dear (91 Classic)

Cruise control was working fine and then on way home from gamefair last Friday it suddenly wasn't working, I tried several times and it would seem to start working and the the speed would drop.

Could anyone tell me what I should be checking and where. I know it's something to do with a vacum pipe but farily clueless after


I read this advice on another thread but not sure where to look for the bellows etc.

I would suggest the 1st thing you do is check all the vacuum lines for perishing at the ends, there should be enough slack to trim off the perished part to good rubber, normally the 1st 1/2 inch. Also check the bellows are holding the vacuum by compressing manually and blocking the vacuum pipe, the bellows should hold closed and not spring back.


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My cruise control is intermittent, my brother's Disco CC didn't work at all - in his case after thoroughly checking out all the wiring, switches and relays he replaced the cruise control ECU & now it works.

I suspect mine may be the same remedy as i have also checked thoroughly all elements of the system:

Brake and clutch electrical cut-out switches & mechanical vacuum vents (immediately dissipates the vacuum when pedals are pressed for safety)

Relay behind driver's side kick panel

steering wheel switches

master cruise control switch

pump operation (vacuum pipe was perished at the point where it connects as it follows a sharp bend at this point)

Mine works when it wants to so i am suspecting a proverbial dry joint in the ECU which is located on mine above and to the left of the clutch pedal behind the lower steering wheel dash panel

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