Electrical

Diagnosing Cruise Control Failure

As far as the cruise goes, the very first thing I would check is to make sure that the actuation
cable is present and is fairly taught. It is the lowest cable on the throttle linkage if I'm not
mistaken and it comes from the left front fender area. The vacuum servo is in the left front
fender behind the wheel. It is easy to get to; just take the wheel off and pop the plastic inner
fender out. It is held in by six or eight small screwbolts. That was just for your information
because you may never need to go in there. If the linkage is very loose, (unlikely the problem)
you can adjust it at the linkage with the nut that is there. It is fairly obvious. The next thing to
check is the vacuum lines. Vacuum leaks happen often and will cause failure of the cruise. You
will see 2 lines running down from the brake booster into the left fender. They go to the cruise
servo. You need a vacuum pump to test them. Just hook up the pump and give it a few strokes;
the lines should hold vacuum. One line will pump up right away and the other you will have to
pump for a while (about 10 strokes) because it is the vacuum reservoir located next to the cruise
servo and it has a larger volume. If they hold vacuum, that is good and bad. It means they are
fine, but your problem is electrical. If they don't hold find out why. It could just be that the lines
are bad or popped off- easy fix just replace them with standard vacuum hose. It could also be
that the vacuum servo or the reservoir is leaking. Not as easy but probably fixable without
replacing. I've had mine apart so if you get there and find one of those is bad meaning not
holding vacuum, let me know and I can definitely help you there. If everything checks out here,
and it probably will, then your problem is either in the wiring or most likely of all BAD NEWS -
your computer is dead. Once you check out all of this and find it working correctly, let me know.
I have the manuals which detail how to diagnose the electrical very very well. It is really easy to
diagnose so don't get scared. Just let me know and I'll send or fax them to you. All you need is
a multimeter and it is very straightforward. In my case I found 2 problems. First I found a short
at the vacuum servo and I thought I had the problem down. I disassembled the servo and
rewired it internally. That's not as impressive as it sounds; its a very simple servo switch. The
short went away but the cruise still didn't work. I diagnosed further and found the computer to
be faulty which happens a lot. I haven't checked too much into a replacement but I know they
are expensive $400-600 new.