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1999 Cruise Control Issue

Redheddedxj

NAXJA Forum User
Location
PNW
I recently bought this XJ and have been trying to figure out the cruise problem since. I suspect a vacuum leak, but before I replace all the vacuum lines since I can’t seem to pinpoint a leak, I was wondering what else I should check?

Jeep is a 1999 auto with a Jasper replacement motor, has roughly 5000 miles and has been running great.

My issue is not setting speed. I can turn the cruise on, the light works, but won’t set at a speed. Now I have had it working after tinkering on stuff, but only short lived and can’t pinpoint the issue. Gotten my hopes up a few times! But now it’s driving me crazy :confused:

And any reason to stray away from this? Correct me if I’m wrong but wouldn’t the vacuum system be different from a 91 vs a 99, curious how one kit works for both....
https://store.hpsimotorsports.com/p...-vacuum-hose-kit-jeep-cherokee-4-0l-1991-2001

Appreciate any help! Have the next few days off so I can try any suggestions!
 
That kit is kinda cool. Seeing how it is vehicle specific. My guess is that not every line gets used depending on the year. Cause as you pointed out there must be some differences between years. Thing is if it is a vacuum issue you might just need a small amount of hose. Figure you have the short piece going from the actuator to the tee. And it could be that rubber elbow on the actuator. Then there is the length going from the tee to the ball behind the bumper. Are you sure that line is hooked up. The little nipple on the ball that the line connects to could have broken off. Which means you might need a new ball there. Last the longer line going from the tee to the firewall, can't remember where that ends up, could be the problem. My point being is the kit, while kinda cool, might be overkill.
 
I would think if you have a vacuum problem bad enough the cruise isn’t working at all you would notice it in other ways. If you have the AC on blowing out the dash vents, do they switch to the defroster vents under hard acceleration? That’s usually an indicator of a vacuum leak.
 
Yes I have looked over the vacuum system and everything looks connected and no cracks. And the A/C and vents work fine, they switch from defrost fine. So maybe I don't have a vacuum leak? What else needs to be checked? speed sensors on transmission? I know the buttons on the steering wheel work because I have had it working before.
 
You say that but the switches send signals across the harness and are known to fail!
 
okay, so I will check the switch, I read one thread about a small box with a pressure switch on the brake pedal that is connected to cruise, but can't seem to find the part online. No other thread that I have seen mentions that, is this something that needs changed?
 
It’s probably the same switch that turns on the brake lights. It turns off the cruise when you hit the brakes. You could try disconnecting it and see if you still have the problem. You’ll also have no brake lights so be careful. It could also be the wiring harness inside the steering wheel, the clock spring, or the wiring out to the actuator.
 
I guess I will just have to start replacing some parts, I will start with cheaper first. Just read another thread where a few people had a similar issue but they had whole system shut off intermittently, my light always stays on just won't set speed.
 
replaced the brake light switch, didn't fix the problem. Worked temporarily on the way back home, but that seems to happen when I mess with stuff, could be from what I was messing with earlier but I don't think this fixed the problem at all.
 
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