The cruise control on my '93 940 works most of the time. Occasionally if we hit a bump, it will drop out of cruise and will not re-engage. Turning it off and then back on a while later will sometimes cause it to re-engage. Any tips as to why this happens? TD

 

Most likely the brake pedal vacuum "dump" switch is adjusted too tightly and a little bump activates it, losing the vacuum, etc. Adjust the switch so the pedal travel needed is longer before this occurs.

 

This does make sense. Where is the switch located?

 

Is the cruise-control vacuum dump switch adjustment involve lengthening the cable from the vacuum diaphragm to the throttle plate control drum where the throttle cable also attaches?

 

The switch is on top of the brake pedal under the dash, black plastic, metal clip. You have to turn it to where it's harder to activate and not open when the pedal is slightly moved... You can do this just by turning it while in place--no need to take it out. You can test its function by keeping the pedal up with your foot, not allowing it to disengage the switch by going down. Manual cars have two switches, one for the brake, the other for the clutch.

 

Thanks Lev. Perfect description & instructions. TD