A couple months ago my cruise control would stay on for a couple minutes, then would seem like i hit the brake and kick off, then i had bad rear shocks and it seemed that every time i hit a bump it would turn off so i figured it could have just been that, about a week ago i replaced my rear shocks and the same problem, when this first started my speedometer would jump back a couple of miles an hour, then read the actual speed, this problem with the speedometer would happen without cruise control on, and would happen when traveling at a constant speed, it got worse and worse, now it will jump forward and backward like 15mph,but eventually go back to the actual speed, i never noticed a loss in power when this has happened.

It'* possible the cruse is shutting off because of a out of adjustment brake switch. If you take off the panel under the dash on the drivers side and look up on where the brake pedal goes up, you should see something that looks a bit like this.



The bottom one is the brake light. Give it a twist


Push the brake pedal in just a little and then push the switch in just a bit, then turn it back. This is how the switch is adjusted. It has teeth.


Try to move it one tooth.

The bad brake switch doesn't explain the jumping speedo. Take a peek at your VSS(vehicle speed sensor) and see if it is secure on the transmission and check the wiring connector.

ok...i'll give that a try...my tranny'* been slippin like crazy lately too...it seems that the speedo will jump right before it slips...sounds like a possible cause

Trans slips right before speedo jumps? If memory and experience serves me right, your VSS gets its reading from the differential. But your trans is slipping? Somethings not right, either these 2 symptoms are related, or they are not. For your sake, I hope they ARE NOT related.

On another note, I am aware that on some vehicle platforms, the cruise control works in conjunction with your ABS and VSS and traction control. I'm thinking the erratic speed indication is having an effect on your cruise, thus the reason for it shutting itself off. With some vehicles, an erratic ABS sensor may causing the TC to think the vehicle is slipping causing the cruise to disengage. I hope someone can back my theory up on this one.

i'll get under there tomorrow and check things out and see what i can find is loose or whatever

where are the abs, vss, and traction control sensors located?

That would be located on the wheel hubs. Just look for the wire.

yeah, and that would be the abs sensor right? where are the other two located? I'm mainly concerned about the vss sensor, I'm pretty sure it is located on the transmission but i need to know where at on the transmission this is located, i don't know what it was but there was a wiring harness on the transmission towards the right side of the engine compartment under the air box, i dont know if this is the vss, but i checked it today and everything seemed fine with that particular harness.

Does the speedo drop to zero at the same time that the trans slips? If so, you have a VSS or VSS wiring/connector issue.