I posted a thread earlier about my cruise control being intermittent. I tried to find to update that thread rather than starting a new thread about the same subject but the search sucks more than my ex-girlfriend.

Anyway, I drove from Phoenix to Denver today. As I was driving I decided to try and use my cruise control that hadn't been working. To my surprise it worked, at least for a while. It has me confused because there seems to be no rhyme or reason to when it decides to work and when it doesn't. It worked for a stretch of about 150 miles and then after stopping for gas it decided not to work for a while. It had been working for about 20-30 miles then cut out on its own without any input from me. Even happens on flat ground so hills are not causing it. Once it cuts out I generally can't set it again for about a half hour like the ECU needs time to cool or something.

I'm completely at a loss where to start looking to track down my intermittent problem. Could it be a slowly leaking vacuum diaphragm somewhere in the system? Not really sure how the vacuum system works so I don't even know if that is possible. Could it be something getting hot and needing to cool before the system will work again? Just throwing out the possibilities I have thought of. If anyone has a better idea please let me know. Long trips suck with an intermittent cruise control.

 

Hi,

I notice with my 2002 the clutch pedal doesn't come back properly then I get this proplem,so if you have a manual,check the clutch and brake pedal switch,just an idea.

Good luck.

 

Thanks for the suggestion. I have an automatic so a clutch is not the issue. The first thing I replaced was my brake switch so I am assuming that is not the problem. I will climb under the dash today and verify the brake switch is adjusted properly though.

 

there are 2 switches on the brake pedal, I also have heard from other people that this is how the ECU begins to fail, works on and off for a while then just stops working.

 

I was kind of thinking that the ECU was probably the problem. The fact that it works some times tells me that I don't have a vacuum leak anywhere in the system. When it works it works very well. I will say I was impressed. Being able to use it at least part of the drive back from Phoenix made for a much more enjoyable trip.

 

there was a "test" sheet about the cruise control system that I found very helpful. I basically dropped the glove box (4 bolts) then the cruise ECU was right there (after determining it was bad I removed mine, that was a pain) but a little metal retaining clip holds the plug on (I used a small screwdriver to pry that off) then all the wires are clearly numbered on the side of the harness. the "test" sheet tested every wire in that harness with the exception of one (I think it was pin 9, which basically disables the cruise if either the brake is pressed or a non moving gear is selected, however there is another pin, 5 I think, that monitors the brake switch). you can also use 2 small jumper wires and turn on the vacuum pump, and an additional 1 jumper to switch the solenoid and activate the accelerator actuator. These tests will tell you exactly where your fault is. If you decide to do this and cant find the test or want some help let me know and I can walk you through it.

 

Thanks Chris. I will look up that test procedure. Sounds pretty straight forward.