Stability System Disabled/Engine Power Reduced

[NotJLB]

P0220 Throttle/Pedal Position Sensor Switch

&

P2135 Throttle/Pedal Position Sensor Switch A/B voltage Correlation

The two recurring codes that put it into Reduced Engine Power indicate the throttle pedal senor is the problem, so that is probably what a repair shop would do. I can do that, but since I've already done that, my guess it's something else. My gut tells me it has to do with the pedals being adjustable, and moving them causes the issue.

For now I'm hold, waiting for an ex-spirt.

 

[NotJLB]

Here is the video for replacing the pedal sensor, not all that tough of a DIY. This is an adjustable pedal, and you can see that cable attach to the top of the pedal that I am trying to identify. I'm guessing it's part of the adjustor actuator, since the fixed pedal does not have it.
If I get no other suggestions, I will do this first.

 

[NotJLB]

Here is a discussion answering the question I have about that cable attached to the accelerator pedal. I don't think I got it locked it like says when I did that a year ago.

Disconnecting adjustable accelerator pedal

I’m trying to replace my accelerator pedal sensor assembly on a 2004 Yukon. This is an adjustable accelerator and the wire that I don’t know how to unplug goes to the adjustment motor. I’ll try to attach a photo that shows the problem area. Does this pull straight out? Do I need tools to unplug it?

www.tahoeyukonforum.com

 

[NotJLB]

Having not heard any other suggestions and assuming my NAPA Award-Winning mechanic won't do anything more than what the codes say, I am proceeding to replace the pedal position sensor, just like I did as a first step a year ago.

I have already heard back from David O'Reilly/O'Reilly Auto Parts, so the saga continues.

 

[tooleyondeck]

Having not heard any other suggestions and assuming my NAPA Award-Winning mechanic won't do anything more than what the codes say, I am proceeding to replace the pedal position sensor, just like I did as a first step a year ago.

I have already heard back from David O'Reilly/O'Reilly Auto Parts, so the saga continues.

I would recommend not using the O'reilly Parts brand, go with AC Delco for your pedal position sensor.

Did you already replace your throttle position sensor on your throttle body?

 

[NotJLB]

Too late.

I just replaced the pedal position sensor and it did not change anything.

Last year I replaced the pedal position sensor and then put on a new OEM throttle body, with a new sensor attached.

It did OK for a year.

My guess it is one of the harnesses, or any of a lot of things.

I just did the first thing, the thing the codes suggested, because I figured that's the first thing a repair shop would do.

I've been a GM guy all my life, but this technology is BS.

 

[NotJLB]

I'm not doing a Happy Dance yet, but I replaced the battery and the codes are gone.

 

[NotJLB]

I took it around the block and the APS code came back, plus P1516, a new one. Reduced engine power, of course.

 

[Bigdaddy1234]

I haven't read all 67 pages - but have you tried checking the grounds yet -

 

[NotJLB]

Thanks. I appreciate that video. I have read about bad grounds and wires both last year and now, but I have never seen what and where and someone fixing them.

Since I have replaced the APS twice and the throttle body once, and that did not fix it, I have felt it was something else all along. It's just that there's so many things it could be.

Last Saturday when I got an oil change, they reported "Replace Battery". It reads fine, and I believe it's fine, but I did any way. One thing the guy did in this video is modify the battery connection, so . . . .

For the clicking-challenge, the short of it is that over time . . . . and 20 years certainly is time enough . . . . wires and connections get gunky, and loose effectiveness, and these techy systems can't function without good connections.

This guy cleaned off all the connections . . . "made them shiny".

My wife just said, "Can you do that?" At least now I know what and where.

Oh, by the way, the P1516 code was gone this morning but the two pedal sensor codes were back. I was able to clear them. But, this is too much of a crapshoot to even let my wife take The Beast to Wal Mart.

 

[NotJLB]

I haven't read all 67 pages -

It was 67 "posts", not pages!!!!!!!!

 

[89Suburban]

Solution to Reduced Engine Power Message and p1516. Look Here

I am sure this topic has beat to death on every GM truck and SUV forum out there in the internet, but I would like to share what I have found to fix the dreaded Reduced Engine Power message. I am sure more and more owners of these vehicles are experience this issue as these vehicles age. I also...

www.tahoeyukonforum.com

 

[NotJLB]

Solution to Reduced Engine Power Message and p1516. Look Here

I am sure this topic has beat to death on every GM truck and SUV forum out there in the internet, but I would like to share what I have found to fix the dreaded Reduced Engine Power message. I am sure more and more owners of these vehicles are experience this issue as these vehicles age. I also...

www.tahoeyukonforum.com

Wow!!! I have fighting this since December, 28, 2022, and I see the likely answer was posted by mdmcinti long ago.

I have long suspected this is a grounding issue, and agree with mdmcinti that pedal position sensors and throttle position sensors are not the type of thing that goes bad. After replacing both, the PPS twice, and the throttle body, this morning I looked at the video posted above concerning wiring, and bad connections.

I also agree that a lot of good vehicles probably have been traded off over Reduced Engine Power, and associated codes. We're close to that!!!!

This morning I had the sensor codes again, which erased, but it has been so much of a crapshoot that I don't even want my wife taking The Beast to WalMart. So, I cleaned the easiest-to-do connection, the ground on the top of the firewall.

Time will tell.

 

[89Suburban]

Sorry I missed this thread. I am not to knowledgeable on the cable/wire system you are dealing with. Mine is drive by wire and I went through hell like this last summer. Replacing TB and sensors and pedal. It wound up being the harness had been spliced and the connections were going bad. I made one last ditch effort and started yanking looming off the harness and found the TB sensor plug had been spliced. It was SO frustrating to track down.

I know the feelings you are having with this. I was ready to get rid of it. And it still took me a few months to trust the truck again from having so much anxiety. Now I'm driving the nuts off it. I hope you can solve the issue here. Helping best I can.


Posts 44,236 & 44,239:

What did you do to your NNBS GMT900 Tahoe/Yukon Today?

I’ve been putting this off, but finally dropped my oil pan and replaced the O-ring and gasket. Not the worst job to do, but not much fun either. That said, now my oil pressure is nice and solid in the green. I was getting intermittent low pressure warnings prior.

www.tahoeyukonforum.com

 

[NotJLB]

Sorry I missed this thread. I am not to knowledgeable on the cable/wire system you are dealing with. Mine is drive by wire and I went through hell like this last summer. Replacing TB and sensors and pedal. It wound up being the harness had been spliced and the connections were going bad. I made one last ditch effort and started yanking looming off the harness and found the TB sensor plug had been spliced. It was SO frustrating to track down.

I know the feelings you are having with this. I was ready to get rid of it. And it still took me a few months to trust the truck again from having so much anxiety. Now I'm driving the nuts off it. I hope you can solve the issue here. Helping best I can.


Posts 44,236 & 44,239:

What did you do to your NNBS GMT900 Tahoe/Yukon Today?

I’ve been putting this off, but finally dropped my oil pan and replaced the O-ring and gasket. Not the worst job to do, but not much fun either. That said, now my oil pressure is nice and solid in the green. I was getting intermittent low pressure warnings prior.

www.tahoeyukonforum.com

What harness? Pedal sensor? Throttle body? Other?

I'm doing one thing at a time and still get codes and reduced engine power. Last Saturday my battery read "replace", when I don't think it actually was bad. I replaced it any way.

We're afoot and it's everything I can do to keep my wife from getting another car on Marketplace. We have four cars, but only The Beast here.

 

[NotJLB]

Here's an interesting analysis of a throttle position sensor, obviously something mere mortals would never see or know:

 

[89Suburban]

What harness? Pedal sensor? Throttle body? Other?

I'm doing one thing at a time and still get codes and reduced engine power. Last Saturday my battery read "replace", when I don't think it actually was bad. I replaced it any way.

We're afoot and it's everything I can do to keep my wife from getting another car on Marketplace. We have four cars, but only The Beast here.

Throttle body.

 

[NotJLB]

OK, explain what you're showing.

Is that before and after, or . . . . ????

My wife and I are frustrated beyond belief.

I know it's something relatively simple, but don't know everything I need to look at, and there aren't any repair shops where we're at in the Winter that are willing to spend the time to look at all these forums and videos, and see what all might be the problem.

It is a widespread issue with older GM products. There's no sense getting another one because it is what it is. Fix it and it's OK, if you can figure out what to fix.

We're afoot until I can, and we don't need to buy a fifth car just because we're frustrated.

 

[Fless]

The first two are "before" pics - this is the replacement pigtail from the throttle body someone had wired in before Paw Paw (@89Suburban) owned it. He re-did the butt connections.

The wires can break about 6" or so back from the connector, under the insulation, causing intermittent throttle position values. Best to inspect by feeling the wires for abnormalities under the insulation.

 

[NotJLB]

Here's another way another guy solved the problem. Again, it's all about grounds in an aging GM problem. His last line, "GM can't solve this, but you can."