P38A Cruise control

J L Carr · Sep 29, 2020

Hi Guys. My cruise control has stopped working, so I check the hose from the pedal to the vacuum pump and all seems ok so then changed the red relay and the unit next to it, but still no cruise. So the only thing left to change is the vacuum control unit or have I missed something out like another electrical unit somewhere.

pwood999 · Sep 29, 2020

Go through the trouble shooting guide in RAVE. It's the easiest way to check the system. In my case there was a perished pipe inside the vacuum pump housing. Easy to replace with vacuum hose. Can't remember the size but it's about 3mm inside diameter. Check before buying.

Alternatively attached a short hose to the tee-piece by the pump, and suck hard. You will soon find if there's a leak or good vacuum.

J L Carr · Sep 29, 2020

I replaced the main pipe with silicone instead of the rubber pipe that had perished it's been ok till now, that's why I changed the red relay and the control box next to it. But to no avail that's why I asked about the vacuum unit, as I've had my EAS box of that many times over the past few months trying to sort out my suspension, just wondering if I had done any damage to it.

Marshall8hp · Sep 30, 2020

Check the two "switches" on the brake pedal. One releases the vacuum and the other is the brake light switch. Both must be correctly mounted and functioning for the system to work.

J L Carr · Sep 30, 2020

I know my brake light switch is ok as the car just passed it's Mot, so I'll check the other 1 at the weekend as well as the pipe work. Let's hope it cures the problem.

Mark Piercy · Oct 1, 2020

The brake light switch has two functions.
One for the brake lights and the other for the cruise.

P38A Cruise control

J L Carr

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pwood999

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J L Carr

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Marshall8hp

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J L Carr

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Mark Piercy

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