pineapple_tree

I’m making another post about my cruise control issue because I still can’t figure it out.

Okay. I installed cruise control on my 95 2.5 5 speed. I got the servo, the buttons on the bottom of the steering wheel, and the clockspring to go with it. The buttons I have on mine is the one where you have to press the cruise control on, and then press the set/cruise button to cruise. Except mine doesn’t do that. I have to hold the set/cruise button down, and while i’m holding it down, it works perfect. It sets its speed, controls it, and will even disengage if I brake, or let off the button.

Now. I have tested EVERYTHING. Three times to be exact.

I have the 95 FSM. In section 8H, it details how to test every component of the cruise control system. I followed them to a T and got perfect results. My servo tested good, the PCM tested good, and the buttons tested good. I also tried 2 different buttons, and both work in the same way.

I seriously have no idea what to do next. It just doesn’t make sense. I have studied every wiring diagram regarding the cruise control system and it still baffles me why I have to hold the button down to cruise.

Can someone please give me some insight on this? I’m loosing my mind because I would like to set my cruise and not hold down the button to cruise. I’ve been trying different things for a long long time now, nearly 4 months I think. And everything I do to try and fix the problem, doesn’t yield anything but wasted time.

However, I have noticed something odd. If i’m on the highway and I hold the button down for a bit, then let off it without touching the brake, it will disengage. But, I can feel it try to grab and maintain the speed I want, then it stops and tries again a couple seconds later. And then it stops doing it if I press the brake pedal.

This just makes no sense. Why is it doing what I just said if I don’t hold the button down, but when I hold the button down it works perfect.

please help me.

Crabbi

Im just throwing this out there, but wouldnt that be like a timer on a wiper motor? a small circuit board with a delay timer on wiper motors, i wonder how the cruise servo is controlled?
probly not helpfull but just a thought

pineapple_tree

From what i’ve read, the cruise control system is controlled by the PCM. It takes the vehicle speed into account, and when you set the speed you want to keep, the PCM will either add vacuum to the servo to pull the cable, or vent air from the servo to retract the cable. I think I read that it’s all inside of the PCM, and the PCM controls everything.

BruceB

Taking a shot in the dark, since the pcm only recognizes the cruise circuit when you hold down the button, maybe since the vehicle did not come with cruise control your pcm is incapable of "switching" on the cruise system after the cruise button is pushed. Maybe sourcing out a pcm for your year make model that came from the factory with cruise would be the solution. Like I said, this is a total shot in the dark. Maybe some more experienced people can jump in on this....

pineapple_tree

Im not even sure at this point. I doubt any 2.5L’s came with factory cruise control.

Anyway, everything is there for you to hook up. The wires are there, connectors, everything you need is there. So it wouldn’t make sense that the PCM isn’t doing what it’s supposed to.

But at the same time, what else could it be? It seems that everything I try doesn’t yield anything, but buying a new PCM is a costly fix and it tested good when I did all of that tested.

cruiser54

Is there a vacuum dump switch on the brake switch?

pineapple_tree

Yeah, there is. It’s a dark blue/red wire that leads directly to the cruise control servo.

What are you thinking?

cruiser54

vacuum dump means it dumps the vacuum right at the brake pedal. Kind of a double safety thing.

pineapple_tree

Well, at first I thought that the dual switch inside the stop lamp switch was messed up, and it would make sense because if I just press the button, it engages and then disengages. But it still doesn’t explain why my cruise control works perfectly if I hold the button down, and then it stops working when I press the brakes.

Anyway, I tested it again today. Everything tested good, and each switch worked exactly as it should.

:/

lawsoncl

I think that was only on the Renix.

cruiser54

Very well could be.

BruceB

Here is an idea for what it is worth, if the cruise disengages when the brake is applied, maybe wire a bypass toggle switch on the dash and do away with the cruise button? I would only do this if the cruise actually disengages when the brake is applied.

treemonkee

Check your power switch. It may be a mechanical latch that is failed to stay on.

lawsoncl

This posting implies that it's the PCM that needs programmed. There may have been two different versions of the button, one momentary and the other meant to toggle on/off. I recall my 93 ZJ, that button toggled in/out for on/off.
https://www.cherokeeforum.com/f2/199...ontrol-254902/

pineapple_tree

I think that’s what i’m going to do. I thought these were resistance based, but Jeep didn’t add that until 96. Then in 97, they changed the buttons to go where the horns are.