Cruise control problems
12/17/15, 05:25 PM
#1
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Cruise control problems
I am having a problem with the cruise control on my 1989 Mustang Lx 5.0 automatic. My problem is when I go to set the cruise control it dosent respond right away meaning I have to hold the "set " button down for a lot more time than I should have to. The cruise does work after pressing the "set" button a few times, and the crusie also seems to engage if I let off the gas pedal and then put a little pressure on it and the cruise will work if I tap the brake pedal and hit the "resume" button its very slow to respond and the "coast" button will shut the cruise off. Thanks for your help.
12/18/15, 12:07 AM
#2
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1 - Vacuum leak
2 - Bad actuator.
3 - Bad control unit (computer)
That it's working at all pretty much rules out 3.
So you're down to the actuator and the vacuum that it is getting from the engine. Go to the auto parts store and some vacuum caps: http://www.jegs.com/i/Trans+Dapt/969...L5MRoCY7jw_wcB
Ok, now, first, with the car on, check the vacuum tree. You'll find it on the firewall. Make sure it's not cracked and leaking. Here's what a new one looks like: https://lmr.com/item/LRS-9490A/86-93...0L-Vacuum-Tree
You can test it by spraying it with WD40 or starter fluid. If there's a leak, it'll get sucked in and the engine will hiccup. There's you're problem, replace.
Now it gets trickier. You now have to test each of the different vacuum things to ensure not one of them is leaking. Problem is that it could be the accumulator that's under a fender. Sometimes those split and leak.
So you get one of these: http://www.jegs.com/i/Bosch-Actron/885/CP7830/10002/-1
and you cap off one end of a hose or system, and then start pulling vacuum. If the gauge doesn't stay steady, there's a problem, and it must be fixed. Could be the line, could be an actuator diaphragm in the A/C system... It's time to play Sherlock at that ponit.
It's a time consuming issue. And it may be that after all the tests... all the vacuum is fine and dandy.
So it's the actuator module itself, its leaking and is causing the slow pull on the chain. It may be a small pinhole, but that can be enough in a vacuum system.
If it comes down to that, you'll just have to get a new one... or replace the cruise system with an aftermarket, which entails wiring and all kinds of fun things...
I'd just get the actuator, myself. Or get this one fixed.
Anyway. Hope that helps. Good luck!
2 - Bad actuator.
3 - Bad control unit (computer)
That it's working at all pretty much rules out 3.
So you're down to the actuator and the vacuum that it is getting from the engine. Go to the auto parts store and some vacuum caps: http://www.jegs.com/i/Trans+Dapt/969...L5MRoCY7jw_wcB
Ok, now, first, with the car on, check the vacuum tree. You'll find it on the firewall. Make sure it's not cracked and leaking. Here's what a new one looks like: https://lmr.com/item/LRS-9490A/86-93...0L-Vacuum-Tree
You can test it by spraying it with WD40 or starter fluid. If there's a leak, it'll get sucked in and the engine will hiccup. There's you're problem, replace.
Now it gets trickier. You now have to test each of the different vacuum things to ensure not one of them is leaking. Problem is that it could be the accumulator that's under a fender. Sometimes those split and leak.
So you get one of these: http://www.jegs.com/i/Bosch-Actron/885/CP7830/10002/-1
and you cap off one end of a hose or system, and then start pulling vacuum. If the gauge doesn't stay steady, there's a problem, and it must be fixed. Could be the line, could be an actuator diaphragm in the A/C system... It's time to play Sherlock at that ponit.
It's a time consuming issue. And it may be that after all the tests... all the vacuum is fine and dandy.
So it's the actuator module itself, its leaking and is causing the slow pull on the chain. It may be a small pinhole, but that can be enough in a vacuum system.
If it comes down to that, you'll just have to get a new one... or replace the cruise system with an aftermarket, which entails wiring and all kinds of fun things...
I'd just get the actuator, myself. Or get this one fixed.
Anyway. Hope that helps. Good luck!
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