[northwoodschev]

I have a 2005 Chevy Colorado with the 3.5 liter straight 5 engine and auto tranny.

I have been experiencing a few oddities lately with the cruise control. It would randomly stop working and then start working again. I replaced the brake light stop switch by the brake pedal (part 5 on the GM diagram). It was a $10 fix and I had to try that first. I have not replaced the cruise control stop switch (part 6). I thought the popular stop switch failure would fix things but it hasn't.

The cruise control stopped again going down the highway for no reason. I came to a stop, pushed an umbrella against the brake and the seat and checked to make sure that all the rear brake lights were working, and they were. When I drove a bit more, I noticed that while I was manually driving, the engine RPM was up about 500 RPM. The engine consistently sounded like it was running in 3rd gear. It would not go into 4th, even on the flat or downhill. The tranny did shift in between 1st and 3rd gears, but the 4th gear would not engage. It was at roughly 2800 RPM at 75 MPH...something that would normally be around say 2200 or 2300 RPM. After foot driving for about half an hour, the cruise worked again and magically the tranny up-shifted and the RPM dropped.

Over the past year, I have had a few tranny anomalies aside from this.Once I was at a stop light and when I got the green, I went to hit the gas and all that happened was the RPM revved up (no gear grinding, just non-engagement). I shifted into neutral and back and problem fixed. The same problem seems to have happened when the tranny should have shifted in between 2nd and 3rd or 3rd and 4th before as well. The problems are rare and happen when you least expect it. One thing is for sure now though. I can't go on a trip out of town anymore without this stupid cruise control and transmission problem. I have no lights on the dash by the way, although I have not chec3ked for error codes.

There's a lot of knowledge on this forum. Anybody else ever run into this? Am I screwed? I assume that part 6 for the cruise control by the break pedal doesn't affect the tranny, it is the other way around, right? Any thoughts? I still like my Colorado and just put a new front bumper and LED light bar on it...but these expensive repairs just keep on coming. Please and thank you.

 

[Toughsox]

Just curious but, what is the mileage of your truck?

 

[northwoodschev]

144,000 miles. I know transmissions survival will vary from owner to owner, vehicle to vehicle...but I think I should have another 20,000 miles before it fails. I've read about solenoid valves going bad. Maybe it is the torque converter. Who knows. Any ideas out there?

 

[jcbcts]

The tranny can last a lot longer or a lot shorter than your expectation depending on maintenance, operating conditions and of course lady luck! Anyway, have you checked the tranny fluid? When is the last time it was changed? Has the pan ever been dropped and filter changed? I think you are correct that the transmission behavior is causing your issue with the cruise control. I would focus on that instead of throwing darts at the cruise control.

 

[northwoodschev]

The tranny can last a lot longer or a lot shorter than your expectation depending on maintenance, operating conditions and of course lady luck! Anyway, have you checked the tranny fluid? When is the last time it was changed? Has the pan ever been dropped and filter changed? I think you are correct that the transmission behavior is causing your issue with the cruise control. I would focus on that instead of throwing darts at the cruise control.

Thank you.

I checked the transmission fluid both cold with the engine off and warm with the engine both off and running, and I get the same result. The fluid is about high enough and the color is a nearly clear, pale yellow. I do not see any shavings in it and the only blackness I see on the paper I clean the stick with is from the stick itself. It doesn't smell particularly bad either, but rather like some sort of used oil.

I've checked other forums and the generally state that yellow color usually means it is OK but I should plan on getting it changed at some point soon. I changed it last at around 75,000 miles. Since I am slowly closing in on 150,000, I did plan on having that done at some point anyways. YouTube has different videos on solenoid valves and that they can be fixed without having the transmission (at the expense of giving yourself an oil bath!).

I don't want to shot in the dark replacing random parts anymore, nor do I want to just change out the transmission fluid to only have to have the transmission rebuilt anyways, I think I will bring it to a transmission person to do a check on it to give me some answers. I just don't want to be conned into a more expensive repair than necessary. As aside from these rogue and random problems, the transmission is shifting just fine and the cruise control works. I will try to find the most reputable transmission person around me. I am fortunate I have another ride with 4 wheel drive in case I need to use it through the upcoming winter. I can part the truck until I can afford repairs. Just for the hell of it, I checked out new Z71 pricing and ZR2 pricing and they are up to and over $40,000. That's crazy as my 05' Z71 crew cab was like $27,000. That like a $10,000 - $15,000 jump in just 10 years. I just don't see the value in a new vehicle at those prices. I just don't want my Colorado to become a money pit though.

 

[Toughsox]

Well, usually you dont want to change trans fluid for the first time with that type of mileage if it is starting to give you problems. Worn discs inside still grab due to the suspended particles in the fluid, so flushing it out once the trouble begins is just going to speed up the wearing process in the long run. Hate to say it but you should have changed it sooner (I do mine at 25K as cheap insurance)
What puzzles me here is you stating the fluid is yellowish. Cant say I have ever seen that color but eh, I suppose its possible. I dont remember what my original color was but yellow does not come to mind. What I go more by is, what does the fluid smell like. You will know if its burned as thats a smell you will never forget.

Now, 2 other points I want to mention.
First off..... as a mechanic by trade (not for a private company) I can tell you this.....you bring your truck to a tranny guy, and he WILL find a problem. What he will find and quote you to repair it will depend on how reputable he is but, I promise you, it wont be cheap. So, you might want to go the youtube-way and try to fix or at least, remedy it on your own first.

Secondly, as for the new trucks. My 2005 was $25K out the door. When I ordered my 2016, my 2005 still had a value of over $12 K (private sale) due to mileage and condition. Yes, the diesels and the ZR2 will set you back $40K..... but a stock Z71 which is levels of comfort wayyyyyy beyond our 2005s, is still only around $30 with the right incentives.
Sp after 12 years, to get a new truck for around $20Kish...... well, I know which way I went. I liked my fuzzy math and it wasnt hard to convince the Mrs. (especially when I put a down payment on a new Camaro for her at the same time) :grin2:

My son now has my 2005, which he absolutely still loves and still looks damn good for its age.....so I can see why you wouldnt want to get rid of yours. I would have been just as happy keeping my old one for myself but, once you get into one of the 2nd Gens.....you wont look back.

Either way, I wish you the best in which ever way you go but please, let us know how things turned out for ya. :wink2:

 

[White016]

@northwoodschev

I would double check that brake switch. Isn't there another switch on the brake pedal too? I had a 2007 Colorado that needed the switch and seams like I remember seeing two switches down there. I guarantee at least one of them is for the cruise. Don't forget the PCM looks at the brake pedal position too so it could affect idle speed. Trans too, not to that extent but still......Get yourself a 12 volt test light to check those switches.

l'd take my chances on the tranny and service it. It sounds like a sticky solenoid or valve not a clutch or pump going out. I say that because it doesn't sound like its slipping, just not engaging correctly. You might get lucky with the service.......Good luck!

 

[White016]

as a mechanic by trade (not for a private company) I can tell you this.....you bring your truck to a tranny guy, and he WILL find a problem. What he will find and quote you to repair it will depend on how reputable he is but, I promise you, it wont be cheap. So, you might want to go the youtube-way and try to fix or at least, remedy it on your own first.

aha, you got that right. I worked for a government fleet. I recall one time we were super busy so I sent out a leaking trans to a trans vendor to fix. It came back with a $1200 rebuild. It was only leaking! So yes, there is that.....IIRC it was only the pan too.....yikes! (I never sent them anything again)

 

[jcbcts]

I would change that tranny fluid 1st thing. I have not seen yellow transmission fluid before. Even if it is "a thing", it may not even be the correct spec for a Colorado. Get a gasket and filter kit and drop the pan. Use Valvoline Max-Life or the spec AC delco red fluid.

 

[northwoodschev]

After the most recent data here and a transmission shop fairly confidently stating that the transmission and cruise control issues are separate issues, I decided I had nothing to lose. I bought a GM cruise control brake sensor (left of the stop light sensor and has a black wire connector). Now I have replaced both those sensors for about $40.00 total. So I took the truck for a ride tonight. The transmission showed no issues and went into 4th gear or the torque convertor kicked in just fine...but the cruise control did not work at all. I didn't see any corrosion around the pins on the old sensor,

I will have to check the connector plug and maybe clean out the connector pins with a Q-tip and some rubbing alcohol tomorrow during the day I'm not impressed. But maybe it was a different problem causing the cruise control to not work at all and it will work tomorrow. I'm about ready to give up! The transmission worked just fine today. Last weekend, it seemed to rev higher ONLY when the cruise control did not work/ I wonder what else could cause the cruise control to fail? Maybe it is the Speed Stick off the steering column itself? I will get the transmission fluid changed shortly thiygh, even though my mechanic says the colors don't usually mean anything unless it is dark or there is shavings.

 

[White016]

After the most recent data here and a transmission shop fairly confidently stating that the transmission and cruise control issues are separate issues, I decided I had nothing to lose. I bought a GM cruise control brake sensor (left of the stop light sensor and has a black wire connector). Now I have replaced both those sensors for about $40.00 total. So I took the truck for a ride tonight. The transmission showed no issues and went into 4th gear or the torque convertor kicked in just fine...but the cruise control did not work at all. I didn't see any corrosion around the pins on the old sensor,

I will have to check the connector plug and maybe clean out the connector pins with a Q-tip and some rubbing alcohol tomorrow during the day I'm not impressed. But maybe it was a different problem causing the cruise control to not work at all and it will work tomorrow. I'm about ready to give up! The transmission worked just fine today. Last weekend, it seemed to rev higher ONLY when the cruise control did not work/ I wonder what else could cause the cruise control to fail? Maybe it is the Speed Stick off the steering column itself? I will get the transmission fluid changed shortly thiygh, even though my mechanic says the colors don't usually mean anything unless it is dark or there is shavings.

Cruise doesn't work after both the switches replaced? Did you check all the brake lamps including the 3rd on top of the cab. ?? Speed stick? what do you mean by that?

 

[northwoodschev]

Cruise doesn't work after both the switches replaced? Did you check all the brake lamps including the 3rd on top of the cab. ?? Speed stick? what do you mean by that?

The "Speed Stick" is GM;s old name (from the 1990's) for the directional signal/wiper control/cruise control stalk. I actually had mine replaced once under warranty as the wiper rotational bit was getting sticky. I thought maybe that had something to do with it.

Another blog here stated there is "adjustability" in the sensor(s). If this is the case, where? It looks pretty stationary to me. Also, on another blog elsewhere, someone spoke of a 2007 GMC Sierra with a similar problem with the cruise control. After contacting the government and filing a complaint, he finally was told there there was an adjustable part of the bracket or bar that holds those sensors in place. The tightened a rather weak bolt and the problem was solved.

Have you or anyone else ever heard of any sustainability of the sensor bar and/or the sensors themselves?

 

[White016]

The "Speed Stick" is GM;s old name (from the 1990's) for the directional signal/wiper control/cruise control stalk. I actually had mine replaced once under warranty as the wiper rotational bit was getting sticky. I thought maybe that had something to do with it.

Another blog here stated there is "adjustability" in the sensor(s). If this is the case, where? It looks pretty stationary to me. Also, on another blog elsewhere, someone spoke of a 2007 GMC Sierra with a similar problem with the cruise control. After contacting the government and filing a complaint, he finally was told there there was an adjustable part of the bracket or bar that holds those sensors in place. The tightened a rather weak bolt and the problem was solved.

Have you or anyone else ever heard of any sustainability of the sensor bar and/or the sensors themselves?

That makes absolutely no sense to me. A Cruise Control sensor?? huh?? What looks stationary to you? Are you talking about the brake switches? Yes, those can move inside their bracket, I remember they can slide in and out of the bracket. Should be able to tighten it up somehow....

 

[northwoodschev]

That makes absolutely no sense to me. A Cruise Control sensor?? huh?? What looks stationary to you? Are you talking about the brake switches? Yes, those can move inside their bracket, I remember they can slide in and out of the bracket. Should be able to tighten it up somehow....

Sorry on the prior message, I mean to say cruise control and brake SWITCHES, not sensors!

Some hopefully positive developments. Today I checked the two switches and the bracket for any adjustability. The bracket has some flex to it and is open on the left side, so I tried to pinch it together a bit with me fingers. I don't think it did much. There is some sort of clip setup holding the bracket to the brake pedal assembly...not really adjustable.

At first glance, both switches seemed seated, but I noticed the newly installed cruise control switch on the left had the white plastic (before the plunger) a little further away from the metal bar than the stop lamp switch I put in a few weeks ago. When I went to remove and re-install both switches, I realized the cruise control switch was able to be pushed in about 1/4 inch further. Strange the assembly still allowed me to turn it right to lock it in even though it was not all the way in in the first place!

That being said, I took the truck on the highway for about an hour to test things. The cruise control worked literally right away and did not go off in areas of the highway that it did before on the last 3 test trips. Also, the engine RPM remained at expected ranges for each gear. I won't know if the re-fitting of the cruise control switch fix is the permanent fix as the problem has been annoyingly sporadic...but this is encouraging. I think I will know for sure on my next big trip. Any maybe that cruise control switch was tripping open in error and sending something to the PCM to mess with the tranny. I guess I may never know!

As far as the tranny fluid,,it's got a bit over 60,000 miles on it and it has probably been 8 years, so I guess it is time for a change. I had never had any check engine light issues and I did a code check anyways and there was nothing on there. If there was a tranny issue, something probably would have shown up. That's another good sign.

I will post more in future weeks and months after I got for another long trip and get the transmission fluid changed out. I have attached a few good photos with info on it regarding both the stop lamp and cruise control switches showing the DIY installation error I made and also the switches you will need out there if you need to replace either or both. The GM part schematics are not really helpful for figuring this stuff out. I hope this helps people out there with the same problem.

 

[northwoodschev]

I've taken several 2 hour long trips with the Colorado since I properly seated the cruise control stop switch (and reset the stop lamp switch for good measure too) and the cruise control has worked as it should without issues. Also, the tranny is running in normal RPM at all times (so far). Maybe the PCM was "confused" by the faulty switch. I just hope this is not a short term fix and that I just encountered good luck. Since I think I found the problem and fixed it, now I am getting the ATF changed, a new filter installed and the gasket properly cleaned. Hopefully getting rid of the clearish ATF will do the trick and prolong the tranny's life. Time will tell. I think at 143,000, there should still be plenty f lift left in the tranny and other parts.