Reduced Engine power, Service Stability System

[Gstepha0]

Hello all,
I'm new to the group as I purchased a 6.0 2006 Yukon Denali from my dad with a little over 240K on the clock. Don't let the mileage fool you though, this truck as been extremely maintained its entire life and looks as good as if it just came off the show room floor with a couple of things added to it.

We are currently fighting the issue of the truck going into limp mode related to the TPS. We've been fighting this for a little over a year now and have done EVERYTHING to fix it. Anything from adding grounds to everything related, replacing harnesses, replacing throttle body's multiple times, pretty much everything that can be related to it was replaced and still haven't gotten the issue resolved. We luckily stumbled upon an old GM master tech and he informed us we have to make a harness specifically for the throttle body (this was GM"s fix to the issue when it as kicking everyone's butt back in the day). The only issue is that we cannot find someone who's willing to make us a harness and I'm curious if anyone who's had this issue and has done the wiring harness to fix the issue had someone do it for them, and if so, would be willing do make one for my Yukon.
Thanks

 

[strutaeng]

I've heard of the issue but I have no direct experience with the problem. I'm actually working on re-looming the harness on my 06 Suburban right now. I did find a few wires with chaffing and I'm fixing that. I only decided to do this because the loom was all damaged and missing in a lot of parts.

You can probably just make yourself a new harness from the ECU and run it to the drive by wire throttle body. It's like 5 wires IIRC. Just look up the wiring diagrams. They sell the little terminals that go to the ECU. I've got some pictures on how to do this somewhere; it looks intimidating but it's not that bad. You can download the vehicle-specific diagrams from AllData for $20 for one month access.

Welcome to the forum!

 

[Fless]

Is this a different kind of harness, or just a replacement harness?

Many times the harness near the throttle body has a broken or compromised wire within inches of the connector, and a new pigtail on the TB corrects that. The defective wire is not easily visible since it gets broken under the insulation. If a very careful hands-on inspection (to be able to feel the wire problem) of the TB wiring hasn't been done, I'd suggest doing that.

 

[alpha_omega]

I've heard of the issue but I have no direct experience with the problem. I'm actually working on re-looming the harness on my 06 Suburban right now. I did find a few wires with chaffing and I'm fixing that. I only decided to do this because the loom was all damaged and missing in a lot of parts.

Yikes! Nice find. How did you track down that chaffed wire? Was it by luck or did you notice a spot where it could have been rubbing?
Have you replaced your motor mounts yet? I’m asking in regards to one of the ways some random chaffing and damages to unrelated parts has happened to other members.

We are currently fighting the issue of the truck going into limp mode related to the TPS. We've been fighting this for a little over a year now and have done EVERYTHING to fix it. Anything from adding grounds to everything related, replacing harnesses, replacing throttle body's multiple times, pretty much everything that can be related to it was replaced and still haven't gotten the issue resolved.

I’m not familiar with this specific fix you are referring to, but I did have a similar issue that occurred to my 2011 6.2l Yukon. Mine was fixed from one of the three repair methods I tried after dealing with the issue during highway traffic. This is one safety issue that is extremely unsafe, especially when you’re trying to get out of the way for 70mph traffic.

You already mentioned cleaning/replacing the grounds. Did you also check the one in the B-pillars on the passenger side (front windshield where it meets the dash)?
The other thing to check is the purple or purple and white wire under the dash at the footwell attached to (I believe) the gas pedal, but it could be the brake. My memory is not as good as it once was. If need be I can go take a look to be sure. While down there I also replaced the brake position sensor/brake light switch GM p/n: 25981009.

I replaced the throttle body but still had issues, which is why I didn’t think this was the cause in my case.

 

[alpha_omega]

Is this a different kind of harness, or just a replacement harness?

Many times the harness near the throttle body has a broken or compromised wire within inches of the connector, and a new pigtail on the TB corrects that. The defective wire is not easily visible since it gets broken under the insulation. If a very careful hands-on inspection (to be able to feel the wire problem) of the TB wiring hasn't been done, I'd suggest doing that.

Similar to the wire I mentioned in the footwell, I could see how this would be a potential issue. Anytime work is done that requires the harnesses to be moved puts strain on the already fragile and thin wires.

 

[strutaeng]

Yikes! Nice find. How did you track down that chaffed wire? Was it by luck or did you notice a spot where it could have been rubbing?
Have you replaced your motor mounts yet? I’m asking in regards to one of the ways some random chaffing and damages to unrelated parts has happened to other members.

I just moved around the wires and noticed the chaffing. Some wires were pretty caked up gunk so I sprayed with purple power cleaner and wiped them down as best as i could before installing new loom. I'm still waiting on my order for the large loom to replace, so I'll be looking out for more of that.

Some wires right at the sensor connector had missing insulation, like the camshaft position sensor and one my transmission speed sensors. I applied some of that liquid electrical tape on those.

I'll probably create a thread on the procedure. Removing the harness is kinda of a pain.

Motor mounts? No, I haven't replaced those. Last year I did remove my transmission due to a rear main seal leak, but the motor mounts looked good. I'll double check when I reinstall the harness.

 

[Eldiablo]

what I dont get is , this tahoe has been bulletproof for years and years and years. Then all of a suddenj wham, now its just frustrating. To me, it starts right up, when its about to do its thing last night, it sounded like the flap in the throttle body was fluttering. That is new. Weird.

 

[Tonyrodz]

what I dont get is , this tahoe has been bulletproof for years and years and years. Then all of a suddenj wham, now its just frustrating. To me, it starts right up, when its about to do its thing last night, it sounded like the flap in the throttle body was fluttering. That is new. Weird.

Have you checked your grounds? Especially the one under the ds running board. Iirc there's maybe 3 ground wires grounded at that point. Are you in the rust belt?

 

[Eldiablo]

Have you checked your grounds? Especially the one under the ds running board. Iirc there's maybe 3 ground wires grounded at that point. Are you in the rust belt?

yes sir. But just got done testing the pedal sensor. It fialed the first test. But has power and ground. Do I will order a sensor.

 

[Eldiablo]

yes sir. But just got done testing the pedal sensor. It fialed the first test. But has power and ground. Do I will order a sensor.

Im in california!