Transmission/Cruise control - Transmission Forum

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Transmission/Cruise control
Wednesday, March 14, 2007 3:20 PM
My 2000 4 speed automatic 2200 cavalier has had some transmission hiccups for quite a while now. It feels like when it is in 3rd or 4th if comes out of gear momentarily. The engine doesn't race but I can feel the car loose power. Also when it does this the cruise control kicks out. Sometimes it won't even let me go back into cruise till I stop the car and park it.

I was reading my shop manual and I saw that the cruise control has some electrical inputs from the transmission that enable cruise operation. So with that said I am fairly confident that my transmission problems are electrical. This could be a good thing. Its certainly easier in theory to work on the electrical system then drop the tranny and get it rebuilt. Are there any weak links in the transmission electrical system that might cause something like this?

I posted a few months ago about this and the suggestion I got was to check the fluid. I did that. Also it was suggested that I just some of the transmission additive that stops slipping and rough shifting. I did that too.

Are there mechanical problems in the transmission that could also knock me out of cruise operation? Sometimes just a bump is enough to make it mad. But that doesn't prove electrical I guess, it could be mechanical.

Thanks for any pointers

Re: Transmission/Cruise control
Monday, March 19, 2007 7:59 PM
If hitting a bump is causing it to kick out of cruise, then it's more than likely a loose connection somewhere. I would start by checking the brake switch, it's got a pink and a white wire in it. If it's loose or out of adjustment, it will cause problems with the cruise control. There's another switch there too, with orange and white wires. That is the brake light switch. Doesn't hurt to check it too

Beyond that... it's harder to diagnose over the internet... but I can provide you with some wiring diagrams that may help!

Re: Transmission/Cruise control
Tuesday, March 20, 2007 5:56 PM
I have enough diagrams thanks for the offer though. I recently got a shop manual for those.

I was hoping that there was some commonality between my problems. The brake switch might explain why cruise is kicking out but not why the transmission is shifting (Or at least feeling like it does) I might have multiple problems I suppose. I do appreciate your input though. Have you had or heard of an issue like mine, or anyone else? I am afraid my transmission is failing. 97000 miles on a 4t40e.

I read more in the shop manual and it seems the inputs for cruise control I thought were coming from the transmission are actually coming from the engine PCM. There is the brake input you mentioned and also an input from the vehicle speed sensor.

Not sure but if the vehicle speed sensor was messed up I could see that affecting transmission shift points and also cruise operation.....but then I would expect to see bad or no readings from the instrument cluster and also a check engine light,,,,,
Re: Transmission/Cruise control
Tuesday, March 20, 2007 6:11 PM
Actually, the transmission does use the brake input as well. Pushing the brake will unlock the TCC, which will feel like a shift if you're not used to it.

What's your fluid like? Has it been changed (ever?)? Is the level topped up? I know it's a pain in the ass to check, but if you run it low it will cause problems as well. Worth the time and effort to check it properly (indicated in the FAQ if you don't have it handy in the manual )

Do you have any electrical mods that tap into white or pink wires? Could be a short somewhere too.


Re: Transmission/Cruise control
Tuesday, March 20, 2007 7:19 PM
Hrm I originally thought it had something to do with the torque converter. Thats an awesome point I hadn't thought of that. The fluid levels are good. I didn't have any mods before but I do now. just power locks and alarm no big deal.
Re: Transmission/Cruise control
Tuesday, March 20, 2007 7:45 PM
Does the torque converter lock up in 3rd though?
Re: Transmission/Cruise control
Tuesday, March 20, 2007 7:55 PM
It should, yes. 3rd and 4th. At least on the 00+ models it does, can't speak for all years.

Re: Transmission/Cruise control
Tuesday, March 20, 2007 8:13 PM
Well I have a 2000. Cool, I will definitely check that out tomorrow. Needed a project anyways. Thanks again,

/me crosses fingers
Re: Transmission/Cruise control
Wednesday, March 21, 2007 7:00 PM
I read in the manual about adjusting that switch. Looks straight forward. Push it all the way out and let it pop back in place as you pull the brake pedal to the rear. I did that and no change.

I noticed that when I was driving in cruise if i kicked the brake pedal sideways it would knock it out of cruise. So it sure seems like the switch or harness if flaky. Even pulling the pedal back up with my toe makes it come out of cruise. Of course pressing the pedal makes it come out of cruise.

So, I decided to just pay 11 dollars and get a new switch. So far it has worked perfectly. I ran cruise control and was only stopped by other traffic. The transmission has not had a single hiccup. It looks pretty good. I won't call it fixed yet, but it is certainly looking that way. I can kick the pedal to the side all I want, cruise and transmission work great. I can pull on the pedal, no problem. Awesome!!!

Thanks !!
Re: Transmission/Cruise control
Wednesday, March 21, 2007 8:32 PM
Glad to hear it was an easy fix

Re: Transmission/Cruise control
Tuesday, March 27, 2007 9:27 AM
check the output signal on the vSS

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