Any GM mechanics out there??

[oldsman350]

Well my 2007 Silverado 4.8L V8started acting up this morning when I got off of work. After about 2 miles the engine light came on and "Engine Power Reduced" kept flashing. Just brought it to Autozone to have the code read and its flashing "throttle position sensor" Is the TPS covered under the 100,000 mile powertrain warranty, can I change it myself? Just trying to get a heads up before I have to break down and bring it to the dealership. I know those dealerships like to charge around $80 to scan it with their code readers.

 

[paddle007]

Well...A TPS is not what it used to be. Because your vehicle is drive by wire you have a accelerator pedal positioner sensor( APPS )attached to the gas pedal and a positioner sensor on the throttle actuactor control( TAC ). The sensor on the TAC tells the computer exactly at what angle the throttle plate is at.
I don't know what your code is but my assumption would be something about throttle correlation. Manufacturers really freakout about runaway problems and the moment this system is out of correlation it defaults to a failsafe mode. The problem could be as simple as gunk holding the throttle plate open. This is the most common issue I address.
I would first clean the TAC assembly and reset the adaptive strategies. DO NOT open the throttle plate without unhooking the electrical connectors and my preference is to remove the TAC unit then clean it with a throttlebody cleaner. After doing this you can remove BOTH battery cables and hold them together for a few seconds. I would do this with a scan tool but if not availible I use the battery cable trick.
After starting the vehicle let it idle for about ten minutes.

If all this sounds overwhelming, this is why I have a job.

 

[#1bambam]

If its anything like a dodge it may just need recalibrated.

 

[oldsman350]

I'll try and take it out today and clean it. The guy at autozone was saying something about the the voltage was going up and down with that sensor. I guess thats the problem it got out of correlation.

 

[Bam Bam]

Generally with a TPS sensor there is a "back up sensor" which reads opposite voltage from the primary one, one voltage will read higher when opening the throttle and the other will read lower voltage. That is the "correlation" he speaks of. In most cars I have worked on both of the voltages added together should add up to 5.0 volts no matter what the throttle angle (sensor #1 1.5 volts @ idle, sensor #2 3.5 volts etc etc).

BTW I have a scanner to check and erase codes, but I am not the GM expert (Mercedes Benz yes, GM no) like others here although I am pretty knowledgeable, just not as much as I would like to be. If you could be in the Denham/Walker area this weekend I might could help. God luck .





Bam Bam

 

[hdsprstr]

Had the same symptoms on an 06 silverado I was working on while I was working for Chevrolet. There was a bulletin about the issue and it required a reprogram downloaded into the computer to fix it.

 

[charlie12]

They gave you some good info. My take is never listen to the people at Autozone with their little code reader. The dealer is not using a cheap code reader probably a high price scan tool and they would know what they are reading not like a parts salesperson at Autozone.