Disco I cruise control problem

[Jonathan Greenberg]

My cruise control seems to be working off and on. It will work fine when it is working and continue to do so for the duration of the drive. However on days when it will not function, it does not at all. The light on the dash lights, I checked all of the hoses, and checked for good vacuum at the site where it connects to the pump. The hoses all hold air, and the accuator seems to function properly as well. Any help or advice would be great. I just wanted to seek other opinions about pump or ecu concerns and how to test these units.

thank you

jonathan

[piper109]

If you have the Rave CD, you can follow the diagnostics in section B5 with a little electrical knowledge and a good meter.
The vacuum pump has power at all times the CC is switched on. The setting etc is done by switching the ground on the motor and valve inside the vacuum pump. The ECU is behind the glove box to the left of the big silver ABS box.
As yours is intermittent, I would be inclined to clean the switches on the steering wheel and the contact rings underneath it.

With the battery disconnected (VERY IMPORTANT !!), remove steering wheel airbag, squirt a product like Rid-ox or Deoxit inside the CC switches and up under the steering wheel centre. Do not reconnect battery until airbag is correctly reinstalled.

Good luck,
Steve