i have an 89 iroc w/cruise control
the cruise control usually works good, but ever now and then i will set it and she will down shift and rev out i duno whatshe'll stop at cauze i allways hit the brakes. this isn't good cauze i allmost went into the bumper of a 18 wheeler.
i think this is cauzed by my tps, but i'm not sure itz the only thing that i can come up with
thanks for te help Jonathan

 

Jonathan,

The cruise control is a completely autonomous and independent system. It doesn't rely on information from the TPS. It DOES share VSS pulses with the speedometer and ECM, but as a separate device, just like the speedometer.

Chances are the TV cable adjustment is right on the edge, and the dither, or span of the cruise control is a little wider than it should be. You can adjust the slack in the cruise throttle cable, and adjust the TV cable.

However, if the cruise is set at 65 and you encounter an incline, it will open the throttle to compensate. If the transmission kicks down as a result, so be it. The control will open the throttle as far as necessary to try to maintain the set speed. As long as you touch the brake and the cruise control dumps vacuum and releases the throttle, that is working correctly. If you can increment and decrement the speed by using the COAST/ACC/RESUME functions, the module logic is probably working correctly and you may have some cable or VSS reference issues.

If the speed overshoots by more than a few MPH, I'd check cruise throttle cable for smooth operation and no sticking, and check the wiring to the control to make sure it isn't missing VSS pulses.

 

when i go up an incline my car will decrease in speed. itz like all my cruise control does is hold the pedal in place.

where can i find the tv cable and how do i adjust it

 

when i go up an incline my car will decrease in speed. itz like all my cruise control does is hold the pedal in place.

where can i find the tv cable and how do i adjust it
and when i set my cruise control a 65mph she will over shoot about 2-3mph for a 67mph speed

 

Not that I doubt Vader, (not that any of us ever doubt Vader), but it could also be operator error. I've found that most every GM V-8 cruise control i've ever used tends to 'surge' a little when it first engages. It's usually for just a second, and then the engine speed smooths back out.

Is this happening with the 'set' button or the 'resume' button?
If you hit 'resume' when you are more than a couple MPH below the last speed it was set at, the car will go for some serious throttle, and possibly a downshift. I experienced this once in a Dodge Caravan, when I accidentaly re-engaged a 75MPH cruise setting, while I was going slightly less than 65. I never knew Caravans had rev limiters.

 

cruise control on my 91 RS has done the same in the past...

Cruise control stays engaged until you switch it off or press the brake.

I have a T-5 transmission (5 speed that is) and while on the freeway i mistakenly engaged the clutch...redlined in a heartbeat. Just dont engage the clutch before you turn off c/c or press brake.
I cant help ya if you drive an automatic

 

iknow what ur talkin about, i had it in cruise control on the highway one mornig going to school, and i went to changed the track on my cd player. and i hit the shifter, and dropped he in neurtel and she reved out real quick then i turned off the criuse control