P1515 P1516 Engine Power Reduced

lundgren · July 8, 2007

I just bought a 2001 2500HD 8.1 LB Crew cab with 65000. I was towing my travel trailer this weekend in the mountains in Colorado.

My check engine soon light came on and the message center said: "Engine Power Reduced." Perhaps "Engine Power Eliminated" would have been more correct... I wasn't even able to get off the highway into a safe stopping place.

I checked the fluid levels. Everything was good. The gauges indicated that the temperatures were all fine.

I turned the engine off for a few minutes and tried again. The check engine light remained lit. I got my travel trailer off of the highway. Then the Reduced Engine Power returned.

I towed the truck and trailer home. I got the engine codes read, they were P1515 and P1516.

Any ideas on where to go to find what went wrong?

whmayhew · July 8, 2007

DTC P1515 Electronic Throttle System Throttle Position

DTC P1516 Throttle Actuator Control(TAC) Module Throttle Actuator Position Performance

I would guess that this might be the foot pedal in side your pickup. I don't know for sure. It sure sucks when you get reduced power. It happened this spring with my wife's truck. It would go about five miles per hour. When I got to where I need to go I shut it down for about five minutes and then it had full power, with the light still on. In my case it needed a software update and there was a local dealer aroung. Good luck.

GMTRUCKTECH · July 8, 2007

YOUR VEC. HAC ELECTRONIC THROTTLE BODY UNIT SO IT USES VOLTAGE SIGNALS TO CONTROL THROLLTE BLADE IN THE THROTTLE BODY. WHAT I HAVE SEEN ON THE JOB IS A FEW DIFFERENT ISSUES THAT CAN CAUSE THIS PROBLEM. FIRST OFF THERE IS A UPDATE FOR THE PCM TO ADDRESS THOSE CODES, BUT YOU WILL HAVE TO TAKE IT TO THE DEALER FOR THAT. SECOND THERE IS ISSUES WITH THE ACTUATOR ON THE THROTTLE BODY BINDING UP AND CAUSING THE CODES. THIRD THERE IS A YELLOW WIRE COMING OFF THE THOTTLE BODY CONNECTOR THAT BREAKS INSIDE INTERNALLY AND CANNOT BE SEEN TO THE NAKED EYE. THE BEST WAY TO TEST THAT IS TO GRAB THE WIRE ABOUT 5 INCHS FROM THE CONNECTOR AND TUG IF IT FEELS SPONGY OR BREAKS THATS YOUR PROBLEM. fOURTH THERE IS A GROUND AT THE BACK OF THE PASS. SIDE HEAD THAT BECOMES LOOSE. WHEN I GET ONE OF THESE VEC.S IN MY SHOP I UPDATE THE PCM REPLACE THE THROTTLE BODY UNIT AND CONNECTOR TO IT AND CHECK THE GROUND ON THE BACK OF THE HEAD IF I DON'T DO ALL OF THIS THAT BITCH SEEMS TO ALWAYS COME BACK. GOOD LUCK

123tx · October 29, 2010

YOUR VEC. HAC ELECTRONIC THROTTLE BODY UNIT SO IT USES VOLTAGE SIGNALS TO CONTROL THROLLTE BLADE IN THE THROTTLE BODY. WHAT I HAVE SEEN ON THE JOB IS A FEW DIFFERENT ISSUES THAT CAN CAUSE THIS PROBLEM. FIRST OFF THERE IS A UPDATE FOR THE PCM TO ADDRESS THOSE CODES, BUT YOU WILL HAVE TO TAKE IT TO THE DEALER FOR THAT. SECOND THERE IS ISSUES WITH THE ACTUATOR ON THE THROTTLE BODY BINDING UP AND CAUSING THE CODES. THIRD THERE IS A YELLOW WIRE COMING OFF THE THOTTLE BODY CONNECTOR THAT BREAKS INSIDE INTERNALLY AND CANNOT BE SEEN TO THE NAKED EYE. THE BEST WAY TO TEST THAT IS TO GRAB THE WIRE ABOUT 5 INCHS FROM THE CONNECTOR AND TUG IF IT FEELS SPONGY OR BREAKS THATS YOUR PROBLEM. fOURTH THERE IS A GROUND AT THE BACK OF THE PASS. SIDE HEAD THAT BECOMES LOOSE. WHEN I GET ONE OF THESE VEC.S IN MY SHOP I UPDATE THE PCM REPLACE THE THROTTLE BODY UNIT AND CONNECTOR TO IT AND CHECK THE GROUND ON THE BACK OF THE HEAD IF I DON'T DO ALL OF THIS THAT BITCH SEEMS TO ALWAYS COME BACK. GOOD LUCK

I'm sorry to wake up such an old thread but Roger you were right on the money!! My friend's Tahoe had the same problem and the yellow wire that goes to the TB was broke.

now the question is, how can I replace it? there isn't enough room to solder it, and I can't find the entire harness for sale...

Can anyone tell me what harness to buy or maybe how can I fix the existing one?

thanks!

Del Casler · October 4, 2013

I have a 03 tahoe Z71 it has reduced power 5 time now. I go to the mass air sensor unplug @ plug it in about 3 times works fine. light will be on

will go off next time I start it. I am a retired computer tech. from a GM dealer. Hope this helps.

cashflow50 · October 9, 2013

I had simmilar issues with my 03 yuke. I checked the the throttle body connector wires for breakage and unhooked it. I then sprayed electrical cleaner and applied dielectric grease on the male and female ends of the connector. I also checked my grounds to my ECBM as well as the other grounds. Cleaned and sanded them. The ground on the passengers side head was fairly dirty, but attached tightly. I beleive it is a 13mm bolt. I will prolly spray a grease cleaner to remove all the dirt and grime. Why because that bugger is hard to get at. After everything is said and done.. The Yuke fired up and no "reduced engine power" message. Fingers crossed.