Here's a weird one...

[rockola1971]

I understand you have the experience and knowledge. There's no doubt in my mind. I give that to you hands down and in that regard you have my utmost respect. It's been your career. I was an electronics tech, troubleshooting at the component level so I also understand the effects of intermittent connections including grounds. But even people who are the very best at what they do are still obnoxious as hell when they boast of brag or feel the need to say things like you just said. Sorry but that isn't humor. I could tell you what it is but I'm trying to be nice. Like I said though you have my respect in the knowledge department. Hope that makes you feel warm and fuzzy.

Im warm and fuzzy and its quite fun to boast.....when Im right. Youve been here for quite a few years....it should be me the one that has to be taught the sense of humor thing....not you. Im not right all the time and man enough to admit when im wrong so dont worry about offending me, its almost impossible. Just trying to help fix some C and K chassis. Its all good.

 

[DJ BigDog]

LOLOLOL easy boys!!! I too have 15 years experience in automotive electronics and this particular ground wire escaped even my attention... which I don't feel bad about since it took a GM master tech 2 days and 2 calls to the Tech Help Line to also find this particular ground! rockola1971 I totally got the humor and actually laughed out loud!!! I had to fight my initial "no shit Sherlock" response to that post but hey you were right, it WAS a ground issue!

 

[rockola1971]

LOLOLOL easy boys!!! I too have 15 years experience in automotive electronics and this particular ground wire escaped even my attention... which I don't feel bad about since it took a GM master tech 2 days and 2 calls to the Tech Help Line to also find this particular ground! rockola1971 I totally got the humor and actually laughed out loud!!! I had to fight my initial "no shit Sherlock" response to that post but hey you were right, it WAS a ground issue!

Glad you got your wheels fixed. I know how much of pain it is to be rolling at 55pmh, traffic rolling too and then all of a sudden you are reduced engine power mode and idling. Talk about inconvenient and when the semis are near its not fun. You are probably very lucky that ground didnt waste your BCM.

 

[retiredsparky]

For those who might wonder why a loose or corroded engine ground can destroy a module, one way is when the starter is activated, the only way to complete the circuit is through whatever grounds are available, like grounds that connect to modules, ECM, etc. That is way more current than the modules are designed to handle.

 

[Cooltaurus21]

Glad you got your wheels fixed. I know how much of pain it is to be rolling at 55pmh, traffic rolling too and then all of a sudden you are reduced engine power mode and idling. Talk about inconvenient and when the semis are near its not fun. You are probably very lucky that ground didnt waste your BCM.

I had this similar problem and never seen such a thing. This being my first ever day on this site I can't seem to weed out the rhetoric to get to a straight answer as to what is causing or caused the Reduced Engine Power light to come on can you help?

 

[rockola1971]

I had this similar problem and never seen such a thing. This being my first ever day on this site I can't seem to weed out the rhetoric to get to a straight answer as to what is causing or caused the Reduced Engine Power light to come on can you help?

There are quite a few reasons you can end up in reduced engine power mode. The most common is a bad TPS Sensor and/or the wiring harness(A wire breaks right before it enters the plug) going to it. Other causes are the throttle pedal assembly, TAC (Throttle Actuator Control) Module and all associated subsytem wiring including most importantly their grounds. This module takes inputs and feedback from the TPS Sensor and Throttle Pedal Potentiometer and when they dont agree within a certain percentage it sends the PCM a this isnt right flag which in turn causes the Reduced Engine Power Message on your instrument cluster. This is a typical how it works for GM Fly By Wire Systems (No throttle cable between throttle body and pedal).

I should add that when the "this isnt right flag" is sent, the PCM "thinks" there could be a runaway scenario (throttle butterfly is stuck open) or a mechanical/electrical problem with the throttle within the throttle body which essentially causes the vehicle to go faster than what the driver is commanding at the throttle (gas pedal). So the PCM shuts it all down and forces the engine into Idle only mode.

 

[Alberta Tahoe]

Hello all.
I've posted in the forum regarding a similar condition. The bumpy road being the initiator as is the case here.
Seeing as the solution in the OP's situation was a poor ground, are you able to say exactly which ground it was? The rear of the engine at the firewall is where I've concentrated my most recent efforts although the braided strap that I've come across appears to in good condition.
All other reasonably accessible connections have been examined but there are dozens more (as you are all aware I'm sure).
Any additional information that can be provided will be very appreciated.
Thanks in advance.

 

[rockola1971]

I had this similar problem and never seen such a thing. This being my first ever day on this site I can't seem to weed out the rhetoric to get to a straight answer as to what is causing or caused the Reduced Engine Power light to come on can you help?

The typical cause of this is usually a bad TPS sensor and/or The wiring harness that plugs into the TPS Sensor has broken wire(s) within inches of the plug. The insulation will not typically be broken so you wont be able to see a break in the wiring. Just the conductors are broken which is caused from the wires hanging there and vibrating millions of times a day when the engien is running. You take a piece of copper no matter how big it is and bend it back and forth and it will eventually break. Usually a new TPS sensor comes with a new plug and pigtail of wiring a good foot long. The TPS sensor can also be bought by itself too.
To troubleshoot this problem, let engine idle and go out and wiggle the TPS sensor harness wiring all along its length from the plug to about a foot back and see if you can get it to go into reduced power mode. You can also run the throttle (with engine off) Key on from idle to 100% and look at a scanner while doing it and watch for erratic increases/decreases in the percentage/voltage of the TPS sensor. These values should all be smooth and repeatable throughout the range.

 

[DJ BigDog]

Hello all.
I've posted in the forum regarding a similar condition. The bumpy road being the initiator as is the case here.
Seeing as the solution in the OP's situation was a poor ground, are you able to say exactly which ground it was? The rear of the engine at the firewall is where I've concentrated my most recent efforts although the braided strap that I've come across appears to in good condition.
All other reasonably accessible connections have been examined but there are dozens more (as you are all aware I'm sure).
Any additional information that can be provided will be very appreciated.
Thanks in advance.

the ground in my case was the one at the firewall you've mentioned but the problem is any bad ground will cause this sort of thing so do a thorough exam of all the grounds!

 

[bunchz71]

I had the Reduced ENgine Power on my 2003 1500HD. It was a broken wire on this pigtail.

AC Delco

ACD# PT1572
GM# 88986255

https://www.amazon.com/APDTY-Connector-Throttle-Headlight-Weatherproof/dp/B00C8E9STA


Forum I was using when I found my issue:

https://forums.edmunds.com/discussion/5759/gmc/yukon-denali/gmc-yukon-reduced-engine-power-message