xantia cruise control

avin44 · Post by **avin44** » 07 Jan 2009, 21:52

The cruise control on my xantia does not work and when I push the lever the only thing that happens is a very faint click from behind the glove box, is there a relay there or is it likely to be some other fault ?.

addo · Post by **addo** » 07 Jan 2009, 22:01

The mauve/purple cruise relay is next to the diagnostic socket, under that flop-down internal fuse cover.

A good prospect is corrosion to the brake pedal contact switches. They are NC, braking action opens the circuit which causes the cruise to disconnect. Carefully remove the switch pad from the brake pedal, dismantle on the bench and polish all its contacts with P2000 wet and dry. Finally, spray them with a contact cleaner/lubricant like "Servisol Super 10" then reassemble the switch. WD-40 is not at all suitable!

If it still doesn't work at all - you may have dry solder joints in the cruise PCB. Carefully ease the circuit board out of its aluminium box, and examine microscopically. I resoldered about 20 joints which I couldn't confirm to be adequate beforehand.

There are cases of vacuum leaks on the cruise vacuum module but I's suspect irregular behaviour to indicate this - rather than total nonfunctionality.

Regards, Adam.

avin44 · Post by **avin44** » 07 Jan 2009, 22:46

Thanks Adam for the information, someone did say thay had heard about the brake switch being a possible cause but as the brake lights were working I thought it couldn't be that, I now realise what he meant.
Thanks again.

Post by **xantia_v6** » 08 Jan 2009, 06:33

On my Mk1 car, the hose on the vacuum pump has split 4 times in 4 years, and causes total loss of operation, so is an obvious candidate. This is a design fault, as a 3mm hose is forced onto a 4 or 5mm spigot.

Dirty contacts in the brake switch have stopped it (but intermittantly) twice in 4 years. On the Mk1, the relay is inaudible anyway, but I suspect that you won't hear it when the brake switch is faulty.