in2pro

Welcome to the forum
You might need to check all the wheel speed sensors to each wheel, check the electrical connection, so can get knocked loose. if all is good on the connection front check fuses, if good there, you may have a wheel speed sensor out...

tahoe-somontan

I read all the posts in here and it helped me understand the issue I was running into with my truck. I figured I sum up the posts that I read previous to mine and let you guys/gals know what I did to solve my problem with the stabilitrak. The only thing I can't explain why it goes into a "limp" mode, but I believe it's caused if you get a few or more check engine codes occur. Obviously, you need an OBD reader to find that out.

2007 Chevrolet Tahoe LT 4WD (bought in 2006)
Mileage: 177,037

Symptoms of when I had a stabiltrak condition
===================================
* Engine feels harsh and unbalanced(like a misfire).
* Change of gears in transmission from low gears is harsh. Like the transmission doesn't catch even though it's an automatic. Not sure which gears but it catches and jerks.
* Blinking check engine light
* Annoying blinking messages from display about Stabilitrak Needs Service and Traction control is off and needs service.
* Seat warmers worked intermittently

Mind you that these symptoms occurred when I was just starting my family vacation in the mountains and we just got some fresh snow this season(12/31/2014). After we got back from the trip, I hooked my $20 OBD PocketScan to it and found the following codes:

P0121: TPS/Pedal Position Sensor A CKT Range/Perf
P0307: Cylinder 7 misfire detected
P0307PD: Pending Cylinder 7 misfire detected

Once I noted all the codes, I erased them using my OBD tool and restarted the engine. I now found the following codes occur:

P0300PD: Pending Random/Multiple misfire detected

So based on the information I got, it sounds like a misfire. I decided to find the easiest thing to look into which was the cylinder 7 misfire code. Not knowing where cylinder 7 was on my truck, I Googled it and found this image of where it was located:

http://www.aa1car.com/library/chevy_firing_orders.jpg

So I popped the hood and pulled the plug out of cylinder 7 and low and behold... Freaking spark plug had a busted electrode! I went and checked the other plugs and pretty much 6 out of the 8 plugs were pretty fowled. I'm not sure why since I changed the plugs 1.5 years ago but I think it's attributed to cheap gas. So I decided to replace all 8 plugs again with the same AC Delco plugs that were in there. I then erased the codes and the stablitrak errors were gone.

I drove around a while and the truck feels super better! After about 20 miles or so, the check engine light came back on but no stabiltrack errors(no limp mode). I hooked my OBD tool and found the error code:

P0121: TPS/Pedal Position Sensor A CKT Range/Perf

So I need to figure out what this is, but after driving another 20 miles or so the check engine light disappeared. So I think whatever this sensor is... It's intermittent but I plan to replace whatever the part is related to this code this week.

I've been lucky that I haven't ran into any major problems with the Tahoe as some of you folks have experienced and feel bad for you folks that have spent thousands fixing it. Only major thing I've ran into with my truck was a failed transfer case module(controller to switch 2WD to 4WD). I had to replace it to get the check engine light cleared to pass smog. I found out that I need to get it reprogrammed for my car to get the 2WD to 4WD working again. I found out it's going to cost some serious money to do that. If anyone has someone they can recommend to reprogram it, please send me a message as I'm a hard working single Dad and money doesn't grow on trees.

Hopefully this post has been helpful. I do love my Tahoe and it's the first Chevy I've owned. I paid a lot of money for it and hope that it stays rock solid for another 7 years and more! I plan to drive my kids all around America and Canada with it.

Cheers and Good Luck!

+ Joe

in2pro

Joe, welcome to the forum
Thanks for sharing your experience and findings, that is what makes forums work!
Please keep us updated on your TPS repair

tahoe-somontan

Regarding the code for TPS:

P0121: TPS/Pedal Position Sensor A CKT Range/Perf

I found links on other forums that made sense:

Chevy techs I need some help - Yellow Bullet Forums

I have a 2007 Chevy Tahoe. The engine light came on and - Fixya

So I went ahead and got air intake cleaner from Autozone and used got the following information from youtube on how to remove the air intake hose and not pull the intake manifold.



I used the brick on the gas pedal trick to open up the butterfly valve and man... That thing was DIRTY!!! It was like thin layer of soot was in it and it was

I sprayed it on a rag and started cleaning it as much as I can. The rag picked up a lot of the crap that was in there. I got as much of it out as I could considering I didn't remove the air intake.

Again, the check engine light was already off, but will update if I see the issue reoccur.

winger_bros

2007 New Style Silverado 1500 5.3 - 205,000 miles - hope some of this may help - truck has been throwing the stabilitrak/service stabilitrak in November 2014 when cold (below zero temps) and now again (below zero temps) - the traction light comes on and the message appears that stabilitrak is off and needs service. It clears within 15-30 seconds and goes away - doesn't throw a check engine light or anything else. Checked with my Actron code reader and nothing - which is what i expected. Have decided not to take to dealer since in the past reading codes has been a waste - their rate is near $100/hr now. I have also considered buying a used Tech 2 tool since that one can reset the alcohol level in the ECM.

Some background - bought the truck with 168K, had low oil pressure - replaced oring on suction tube and a bunch of other parts while in there - truck runs very well. also installed the oil shield for the AFM that stops the spray up into the engine. The truck has thrown engine codes PO172/174 rich bank - since i got it - found the alcohol level at 30%, so had dealer reflash ECM - but didnt take real well - i just reset the code now when it appears.

Back to stabilitrak - i have read this forum almost note by note and agree with some of the general posts - there does not seem to be a single reason for the message and problem. So, my plan will be to replace the throttle position sensor ($30 free ship for supposed OEM part from Amazon) and also check each wheel sensor cabling and connections - these two items seem to be the most prevelant in this and other forums. Also, I am getting a Predator programmer to kill the AFM on this truck and the wife's 07 Suburban.

Surprisingly when i did the work last winter on the truck - i replaced the plugs and none were coked up as i would have expected reading here and other places about the horror stories on AFM.

Overall it is a good truck.

in2pro

In the above video, he mentions to not open the throttle plate, you can open it and it will throw off the calibration. you can take it to a dealership to have the throttle learn performed OR drive it in stop and go traffic for a period of time and it will relearn itself, though you do need to exercise caution as the idle can be high and the vehicle will want to move when stopped, but it is manageable..
Don't move the plate excessively or any more than you need to, to get the bore and plate seating surface clean....
The grime build up, as I understand it, is partly oil that is blown or vacuumed back up into the manifold in normal operation of the engine as well as micro fine partials that do make it through any filter medium...

With all of the valves opening and closing multiple times across all cylinders, and not all valve seats being 100% closed and sealed at any given time, one cylinder can be pushing up while another is going down causing the oil and fuel to some extent, to swirl around in the intake... this is how I conceptualize it happening...

tahoe-somontan

Intermittent issues are the worst! I'd say when the message stabilitrak flashes again, immediately pull over and stick the OBD tool on it and see if you get anything. Hopefully you'll find something. Good luck bro!

tahoe-somontan

Thanks for the info! I used the brick on the gas pedal while the key was in the on position(not running) to keep the plate open to clean the intake. It worked out pretty well. Thanks for explaining why the oil was getting in there. I totally forgot about that hose attachment. I believe that's used for the fuel vapor to recirculate back into the intake. I did carefully clean the blade, but the car still is idling high. I didn't force the butterfly valve opened as I was using the gas pedal trick. Any idea how long it takes to recalibrate itself? I'm thinking of letting the truck run idle in front of my house for a while(possibly all day) to fix it. Thoughts?

73shark

Good conceptualizing. The process is called reversion. It is caused by the overlap in the valve timing when both intake and exhaust valves are open at the same time and some of the combustion gases get kicked back up into the intake system.

rkoors

I have a 2007 Tahoe and over past year, it has had intermittent problems with the stabilitrak when it is cold out (below freezing). The stabilitrak system buzzer goes off and the car will start to loose power. It will progressively loose power until it is only able to drive very slowly. If I stop and turn the car off and let sit for 30 seconds or so, it appears to clear out the alarm and the care will drive again. However, when starts to occur, a lot of the time the problem will occur again almost immediately. Also, during these times, even when it doesn't' go into the alarm mode, the car does not run well....appears to have a miss in the engine.


It definitely only occurs when it is cold out. I had the problem last winter, then went all year without any issues and now again it is occurring.