cruise control woes

Sharon Silver

Registered User
When I set my cruise control, it hols until the first time it needs to accelerate or slow down. One any change in speed occurs, the car will blast to speed and then drop to zero throttle, coast down, then blast back to speed. I can't find a vacuum leak. Is this the amplifier?
 
When I set my cruise control, it hols until the first time it needs to accelerate or slow down. One any change in speed occurs, the car will blast to speed and then drop to zero throttle, coast down, then blast back to speed. I can't find a vacuum leak. Is this the amplifier?

mine kind of is the same but its not crazy blast, its just like it hits it like 1/8-1/4 throttle and then lets up over and over.
 
I would check to see if the cable that attaches to the throttle body is loose and does not stick or bind.
 
Same here

mine kind of is the same but its not crazy blast, its just like it hits it like 1/8-1/4 throttle and then lets up over and over.

My '90 SC does the same thing. On cruise control, it wants to surge and let off over and over. Sometimes turning the cruise off and resetting it clears it up. But what's causing the cruise control surge?

eddie
'90 5-speed SC
'97 LX sport
 
When I set my cruise control, it hols until the first time it needs to accelerate or slow down. One any change in speed occurs, the car will blast to speed and then drop to zero throttle, coast down, then blast back to speed. I can't find a vacuum leak. Is this the amplifier?

My guess would be yes. You need to pin out the amplifier and find out if you have a short in it (or replace it with a known good one). The problem is that for some reason the car can not sense the speed or load. This is the same thing that happens if you try to set the cruise with the car on a lift. It will rapidly accelerate and then shut down. So unless the wires that measure the speed sensor are split/cut, I would guess the amplifier is bad.

Chris
 
I can't turn my cruise control on. No matter what I do, it will not set. Fuses are good, so I assume its in the steering wheel. Any ideas of what else?
 
Patrick, isn't there some cruise electronics in the left fenderwell, behind the splash guard? I would check that to make sure it's operating properly.
 
Yes. It is electrical and vacuum controlled. If the cruise is not working at all, the dump valve was usually the culprit, either it would be adjusted incorrectly, or pushed out of position from the retainer. If the cruise is notchy, the first thing I would check would be the cable from the actuator in the fenderwell to make sure that there is no slack in it or any kinks in the cable. If anyone still has problems, or questions, let me know.
 
After all of that is checked, there is a black/white plastic stair step clip under the dash that goes to the brake pedal. IF it is out of adjustment, you need to readjust it, and your cruise will work. If you drive the car and lift up on the pedal with your left foot and you are able to set the cruise, you know that your brake switch (the afforementioned part) is out of adjustment. Ask me how I know....BOTH of my T-birds and one of my best friends. All at the same time.

Chris
 
The cruise went inop on my old 90LX. It was the canister under the LH fender. Junkyard item; easy, cheap fix. If the dump valve, cable and switch wiring are all good, it's Pick-n-Pull time...

JD
 
My guess

I'll be checking on the vaccum lines tomorrow but my guess is that it's the amp. I think it's around the gauge cluster. Anyone know for sure?
 
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