'07 Tahoe Limp Mode!

[TahoeLTZ]

Hi all.

Did some searches on this but havent found real answers yet.

Have an '07 LTZ with 97000 miles on it. No mods--completely stock. Recently having an issue with "service stabiltrak, service traction control, engine power reduced" and of course I have to nurse it to the side of the road and shut it off for a couple of minutes and then restart. Everything is fine (except engine light is on) for about 10 minutes and it does it all over again.

History: had it to the dealer numerous times and they are stumped. Said they called GM and GM is stumped, but has had other similar complaints. Have read no less than 30 things it "could" be, from yaw sensors to front wheel alignments! Dealer changed out my computer first thing (for about a thousand bucks) and it did not fix the problem. I played with the traction control button also by a) turning off traction control upon startup, b)turning off traction control AND stabiltrak upon startup, and c)turning these two systems off AFTER this happens, and NONE of the above have any affect.

I really like this vehicle, but it is no more reliable than my 35 year-old Trans Am! I dont even trust it for any trip now. Last night it actually DIED completely during one of the occurrences, causing me to lose power steering and brakes on the interstate.

Sorry for the long post, but I really cant believe nobody has found a correct solution to this problem, and considering the safety issues involved I cant believe there isn't a recall from GM yet. Thanks for ANY help.

 

[stevek]

I'd think that the dealer could pull up some error codes... it wouldn't just happen without pulling up some codes

 

[TahoeLTZ]

Didnt get the actual code, but the service manager said they were getting a code that said the "computer is unable to communicate." Unable to communicate with other sensors and such? Not sure. Last time it was in they had it for a day and returned it saying a ground wire on the firewall was loose and the culprit. BUT, the first time we drove for over an hour it started doing it all over again.

Today I picked up a new 160 amp alternator to replace the OEM. Expensive for an alternator (200 bucks) but easy to replace, so I did. Now the altmeter registers slightly above the "14" whereas before it would just be below and after an hour would drop to around 10. I am sure that is not normal, but am wondering if anyone knows if the altmeter is SUPPOSED to fluctuate like that?

 

[stevek]

Didnt get the actual code, but the service manager said they were getting a code that said the "computer is unable to communicate." Unable to communicate with other sensors and such? Not sure. Last time it was in they had it for a day and returned it saying a ground wire on the firewall was loose and the culprit. BUT, the first time we drove for over an hour it started doing it all over again.

Today I picked up a new 160 amp alternator to replace the OEM. Expensive for an alternator (200 bucks) but easy to replace, so I did. Now the altmeter registers slightly above the "14" whereas before it would just be below and after an hour would drop to around 10. I am sure that is not normal, but am wondering if anyone knows if the altmeter is SUPPOSED to fluctuate like that?

Mine always hovers slightly around the 14 mark as well. When the battery is fully charged, I believe it'll stop charging the battery. Sounds like you could have a short or that you have a bad battery. Have you swapped the battery out yet?

 

[TahoeLTZ]

We did put a brand new battery in a couple of months ago.

Update: just got back from a "Test" drive after the new alternator, and after about 45 minutes of driving like a dream, it did it again. Exact same symptoms. Plus, the altmeter does still fluctuate, and I too believe this is normal now. So, chalk up another $200 bucks out the window.

I really want to keep this thing, but if the dealership doesnt know how to fix it, how should I? I know that others have had this same problem; how did they fix theirs? Or are they just living with it?

Anyway, thanks for the responses so far....

 

[stevek]

There is a short somewhere, that's my only guess.

 

[gibsonm21]

The voltmeter on the dash is not acurate at all. I have a 300 amp alt and the voltmeter will often hover around 12v, but my volt monitor I installed has me constantly at 15v(except when I'm playing my system at full blast).

I would suggest getting a multimeter and measuring the voltage (at the alternator and at the battery) after you have been driving around and the batt has had time to charge up. With your truck at idle, the voltage at your alt should be around 14.4v and close to that at the battery. If the voltage checks out, then its more than likely just an in-accurate meter on the dash, If the volts are low, then have someone get in the truck and rev the engine to around 2k-2500 rpm and repeat the measurement. If you don't hit 14v with the engine rev'd, then yea, you have an issue!

Like I said before, it probably is just your meter on your dash.

 

[stevek]

Aren't some of the gauges just analog displays for digital information? For example the speedometer, on one of the radio hidden pages, there is a listing for mph...

 

[TahoeLTZ]

Hey guys, found this information about the Regulated Voltage Control system that the newer GM vehicles now have. Explains the fluctuating guage:

Condition/Concern:
Some customers may comment that their voltmeter is fluctuating between 12 and 14 volts on their full size pickup / utility vehicle.

Recommendation/Instructions:
Starting with the 2005 model year, light duty full size pickups and utilities, are equipped with a new Regulated Voltage Control (RVC) system. This system turns off the alternator when it is not required in order to improve fuel economy. The alternator will turn back on when additional voltage is required. This will cause the voltmeter to fluctuate between 12 and 14 volts as opposed to non-regulated systems which usually maintain a more consistent reading of 14 volts. This fluctuation with the RVC system is normal system operation and NO repairs should be attempted.

 

[TahoeLTZ]

Well, did a ton of research on this and it appears the problem directly relates to the Stabilitrak system, which in and of itself is comprised of NUMEROUS sensors and modules throughout the vehicle. It only takes a simple module/sensor malfunction and/or false trigger, or even an electrical surge or glitch, to send the $48000 3-ton vehicle into limp mode, effectively disabling it and making it worthless. I must say, technology has come a long way in certain aspects of automotive history, but it's things like this that really frustrate me to no end. A system that is supposed to make your vehicle SAFER has actually made it DANGEROUS to drive. This Tahoe has the drivetrain, build quality and driveability attributes to easily attain 200,000 easy miles, yet is rendered useless due to a "safety" system installed on it that nobody, including General Motors, knows how to repair. Which brings me to my big question:

Does ANYONE out there know how to permanently disable the Stabilitrak and Traction Control systems? If my Tahoe did not have those features, I would NOT be having any problem with it. And before anyone talks about how these features should stay and will keep me from crashing, please dont waste your time. Vehicles did without these elaborate systems for decades before and I never crashed them (and I live in the snowbelt). These systems are mostly for people who don't know how to drive properly. Sorry if I sound irritated, but quite frankly, I am. Mostly because my otherwise perfect dream vehicle is handicapped by systems installed on it because of a select few drivers that would crash without it.

So anyway, my rant is over. As far as permanently disabling the system, is there a fuse? Will jerking the fuse disable other needed systems (like cruise control, etc)? Can I just unplug something somewhere? Please help! I am at wit's end.

 

[a2t]

why dont you lemon law it?

i saw an 08 hybrid at a dealer south of atlanta which had all sorts of similar issues. they lemon law'd it, then GM replaced the entire trans and they are now trying to sell it again (hennesy gmc).

i didnt touch it, bought another tahoe (which is having its own set of problems).

 

[bigblue]

could be something with the transmission, i have heard on these nnbs tahoes/yukons they have a sensor in the transmission that puts them in limp mode, when the transmission is about to tear up or if it gets hot.

 

[TahoeLTZ]

Hey guys, thanks for the ideas. What makes these forums great is all of us coming together to try and figure out these problems so others can possibly get something out of it in the future.

The Tahoe is at the dealership again. This time, they pulled up 9 stored codes that occurred in the last 3 days. 5 of them were from me pulling the ABS fuses in an attempt to disable the Stabilitrak and Traction Control, as well as ABS, to try and determine if they were malfunctioning and causing the limp mode. 20 minutes into my test drive, it happened again, even with these systems disabled. So I determined these systems were not causing my problem (but still dont like all that crap on my vehicle )

So, the tech ignored those 5 related to the ABS due to me taking out the fuses and causing the thrown codes. The other 4 were all related to the TPS, or throttle position sensor. This was good news as all the other code reads in the past only showed a generic "unable to communicate." After telling the tech that the engine actually DIED on one of the occurences, he stated that having a bad TPS would and could do that. He was almost as excited as I was to finally have a starting point. Unfortunately, he stated the sensor located on the throttle body is part of the TB itself, and would have to replace the entire throttle body... Hey, as long as it gets my Tahoe back to normal I dont care! I will know tomorrow if it is the fix....

 

[JEJ]

Hey guys, thanks for the ideas. What makes these forums great is all of us coming together to try and figure out these problems so others can possibly get something out of it in the future.

The Tahoe is at the dealership again. This time, they pulled up 9 stored codes that occurred in the last 3 days. 5 of them were from me pulling the ABS fuses in an attempt to disable the Stabilitrak and Traction Control, as well as ABS, to try and determine if they were malfunctioning and causing the limp mode. 20 minutes into my test drive, it happened again, even with these systems disabled. So I determined these systems were not causing my problem (but still dont like all that crap on my vehicle )

So, the tech ignored those 5 related to the ABS due to me taking out the fuses and causing the thrown codes. The other 4 were all related to the TPS, or throttle position sensor. This was good news as all the other code reads in the past only showed a generic "unable to communicate." After telling the tech that the engine actually DIED on one of the occurences, he stated that having a bad TPS would and could do that. He was almost as excited as I was to finally have a starting point. Unfortunately, he stated the sensor located on the throttle body is part of the TB itself, and would have to replace the entire throttle body... Hey, as long as it gets my Tahoe back to normal I dont care! I will know tomorrow if it is the fix....

And the answer was? Yaw sensor?

 

[TahoeLTZ]

Well, they replaced the TPS and it did it again right away. Knowing it was a dangerous issue (due to limp mode and at one point the engine quitting on the interstate) they kept it for a week at the dealership. I got it back with an additional 500 miles on the odometer, and they stated they did not find anything in particular but that is seems to be fixed. They stated they contacted GM and followed their instructions to a T by going through every wiring harness and connection, as well as every ground, and making sure they were tight. Dealer said they did not discover any that "appeared" loose, but that after they spent 3 days checking wires, they could not reproduce the problem. We have had it for 2 weeks now, and another 800 miles later it still has not done it. So my conclusion would be that it is wiring related, and probably a loose connection or ground that was giggled or tightened enough to fix it....................for now. Let's keep our fingers crossed! Problem is, if it happens again, who knows WHICH ground or connection was the culprit?

 

[TahoeLTZ]

Jiggled, not "giggled." Tho I am starting to just giggle at the whole situation.

SteveK is probably right: there was a short or loose wire connection. Whatever you do, DONT buy another alternator if you are having this problem. Oreilly Auto Parts tested the old one, and said it passed upon startup and then eventually "failed" after running for a few minutes, and suggested a new alternator. I now know THIS IS NORMAL with the new Tahoes, as the computer manages the alternator output based on electrical needs in an attempt to increase fuel conservation. The old one I had was most likely perfectly OK and I wasted 230 bucks. Just FYI.

My suggestion to anyone else experiencing this is to first check all the wiring connections and grounds on the vehicle. Say goodbye to a weekend.

 

[TahoeLTZ]

Well, after 1200 miles trouble-free miles doing everything from short little town trips to towing a 2 ton boat 300 miles, plus driving up in the hills to a remote cabin, it had to come to an end. Took the Tahoe to the brake shop to have the brakes inspected for a long trip coming up. They removed the wheels/tires and the inspection came back clean, so they re-mounted the wheels/tires without touching a thing. Then shortly afterwards, BAM!, limp mode on a 75 mph speed limit interstate. Not once, but twice within 10 minutes.

 

[viper911ad]

Hello,

I have a 07 Tahoe 5.3 LT. Having the same exact problem. It's happened twice now. First time I replaced the battery, but it's happening again.

Do you have any updates? How is it running now? What did you do to fix it this time?

Thanks,

Adam

 

[TahoeLTZ]

Why oh why am I bothering with this thing?!!??!!

Since I posted last my '07 Tahoe with 102000 miles has limp moded at least a dozen times. Once while pulling a 4000 pound boat up a hill -- that time it not only went into reduced engine power, it actually died while climbing the hill. Thank God for emergency brakes.

I have replaced the battery and alternator. Checked the gas cap for tightness. Checked the throttle body wiring harness connection for tightness and even zip tied the wires tight and then to a solid part on the manifold so I would KNOW the wires were not moving during engine operation (in case there was the common "split" inside the insulation). Still does it whenever the hell it wants. Sometimes 4 times a day, sometimes once every thousand miles. But usually when there are friends/family on board so I can be real nice and embarrassed that I drive a $30,000 POS. Problem is, I like it otherwise. I runs and drives better than any vehicle I have ever owned when not in limp mode. Chevy dealer had it for a total of 20 days over the course of 6 visits and they could not figure it out. Bittersweet I tell ya.

 

[IrishTR]

Probably not an viable solution but I would take it and get rid of it asap... Too much safety and headache concerns! If I ever have a car at a dealership (thankfully mine are all warrantied to 125k) and they tell me they cant fix it... Kiss it goodbye!