GMC Repair: Cruise control, gmc safari, vacuum lines

Question
I have a 1994 GMC Safari van V6/automatic. The cruise has worked fine for many years. However, now it is dropping out. After I reach the desired speed and push the engage button it will take over and hold at that speed. After a period of working fine the speed starts to drop off (slow down). If I depress the accelerator and bring it up to the cruise speed it will again hold the speed for up to 30 minutes then will repeat the slow down.

Any ideas?

Chuck Hall

Answer
There are numerous tests that MUST be performed before any GUESS can be made.

It could be:

1. A vacuum line leak.

2. A cruise controller failure.

3. A faulty electrical connector in any one of numerous connections.

4. A speed sensor failure.

5. A leak at the brake switch DUMP VALVE.


This is going to take expert testing to locate the problem.

You can look at the vacuum lines for any leaks however.