Cruise control not working on 1996 discovery

[tpark]

Greetings,

I have purchased a 1996 Land Rover Discovery, and the cruise control does not work. When cruise control switch is activated, the light comes on, but pressing the "set" button does not make the vehicle hold its speed. The vacuum pump appears weak (I get some slight vacuum from the pump if I hook it up to voltage, but not very much) and I had to replace some of the tubing as it had cracked. I hooked the harness back to the pump, ran a tube from the pump to the vacuum gauge, got the vehicle up to 80km/h, activated the cruise... and no vacuum.

1) Is the vacuum pump an on/off device, with the amount of vacuum to the accelerator actuator controlled by dumping the vacuum (i.e. from the solenoid attached to the ecu) or is the voltage to the vacuum pump controlled?

2) how much vacuum should the pump be able to provide? I tried to obtain a new vacuum pump from the local parts places, but it appears as thought this is not an off the shelf device.

If you know of any resources I should look at, or have some especially wise advice for this Discovery newbie, it would be greatly appreciated.

--Ted

 

[tpark]

Ok, as it turned out the brake switch had come out causing the system to fail. The contacts on the pump are as follows

2
1 3

So 1 would be common, 2 would be the vacuum pump motor, and 3 would be the dump valve solenoid. If power is attached to 2 and 3 (relative to 1) you will get around 15 inches of vacuum. The pump can be disassembled, the cavity (containing the solenoid and motor assembly) doesn't appear to be an integral part of the vacuum system.

Anyway, it works now - other threads in the forum have pointed me in the right direction.