Thread: 2006 GPGT, cruise control doesn't work.

Hey guys. I just picked up a 2006 GPGT to replace my 1998 GTP that was totaled 2wks ago. The car is awesome, I like it a lot. I liked my 1998, and this is everything that was and so much better - 6 disc, both seats heated, intake/exhaust as provided by the previous owner. I need to measure the pulley, but I think thats non-stock as well.

The only problem I've found so far is that the cruise control doesn't work. Its strange, when I active the system (and I've had enough GM's to know exactly how this setup works) the dash light comes on, the DIC shows the cruise set message, and the power-train starts following typical cruise control behavior (holds gears/tc lockup), but the car doesn't maintain speed, you let off the gas and it just slows down as normal. I play with the accel/decel buttons, once you've tried to set it once, pressing anything just give you another cruise set message on the DIC and nothing changes.

Now, I just was reading the manual online this morning and it does say that it won't cruise if the brake fluid is low, which I haven't checked, but I don't have a light for low fluid, and I assume if it was low enough to disable cruise, the light would be on. So, outside of that possibility, any thoughts as to what might be going on?

I have the exact same thing happen when the ABS light intermittantly comes on. I have checked my fluid and it is topped off. Yes I have an intermittant ABS light and I understand that may indicate that I have a bad HUB. The point I trying to make is the cruise only fails when the ABS indicator is on. There is never a low brake fluid light. Could the ABS be trying to tell me there is a problem with the fluid level sensor? Just asking.

Hmm... it just passed inspection so the lights are good, maybe there is 1 bulb in the third brake light out. No ABS light, no lights at all. More investigation to follow after work.

Did you guys notice when it wasn't working that the cuise control icon would still come on, and the DIC would still say cruise set, or not?

As a follow-up, all the bulbs check out and are working as they should. Brake fluid is where it should be. Definitely weird, I'll take any more ideas you guys have got.

Do you have a check engine light? If the computer detects a misfire in one or more cylinders it will also keep the cruise from working. I had this happen to me and found out that I cracked a spark plug when doing the header install. replacing the plug cured my issue with cruise control.

No check engine light. 3800pro forum had to remind me of what should have been my first suspect, the brake switch. And sure enough, seems that the brake switch is out of action, I can't trip TCC lockup like I should be able to.