View Full Version : 03 silverado reduced engine power


meangreen73
02-26-2013, 09:42:29 PM
Not camaro related but having issues with my 03 6.0 silverado 2500 going into reduced engine power. Ill be driving and all of a sudden a message will come on the screen that says reduced engine power. I pull over turn it off for a few seconds start it back up and its fine. The check engine light stays on after about 2 starts after and then goes out until it happens again. The code it comes up with is p1516 which is a problem at the throttle body from what I have read and heard. Ive replaced the throttle body and pigtail and have also checked and cleaned the grounds under the driver side door on the frame rail as well as the one on the driver side cylinder head and still the problem keeps happening. I tow with this truck so I need to get it fixed any ideas?


It also has a cold air intake on it not sure if this could be related or not just throwing that out there. Also it had a problem where it would not start at times and the gauges were malfunctioning. I solved that problem by finding corrosion on the the main pcm wiring harness connector/pigtail. I cleaned it and put dielectric grease on the connector and its been fine since. Not sure if that could be related as well or not...

351maverick
02-26-2013, 10:21:46 PM
THIS^^^ is the reason I sold my 04 Hummer H2

the best I could do was clean the MAF with the appropriate cleaner, clean the throttle body with the appropriate cleaner & make sure the air filter is not restricting flow

MY CEL was always a "voltage variance between the pedal & throttle body"

I finally sold the thing because it was obvious the truck was retarded

bigblockbird75
02-27-2013, 08:25:46 PM
It's probably a problem with the accelerator pedal position sensor. It's been a while since I worked at a GM dealership, but I replaced quite a few of them. If you have access to a scan tool, check the codes, and check the data stream. There should be two PIDs (app 1, app2) If they don't match or within spec(they are allowed a tiny bit of variance) unplug the sensor(s) and check for corrosion. Alot of water and crud finds its way down there.

meangreen73
02-28-2013, 09:23:12 PM
I did check the code. It was p1516 which is a problem at the throttle body. I replaced the ground today and still have the same problem. I put a thread on yellowbullet as well. I work at napa and used a rebuilt cardone throttle body. A couple think I have a defective one from cardone and should defect it and try another one or just get a new gm one.

Paint Fumes
02-28-2013, 10:23:43 PM
I have had this happen with two of mine. Both times it was a bad connection at the battery. I cleaned the terminals and it cleared right up. My last one that did it was a 2003 K2500. It wouldn't even climb my small hill of a driveway. What clued me as to my trouble was it cranked slowly right before it happened, with a new battery. Luckily cleaning the terminals worked for me, hope it's something simple for you too. Good luck.

meangreen73
02-28-2013, 10:34:41 PM
Mine starts fine and runs fine. I'll be out driving and it will do it out of no where. I did check the terminals today but they looked good and the battery is pretty new. I think I'm gonna defect the rebuilt cardone throttle body and either try another one or bite the bullet and get one from GM. I've tried everything else and the problem seems worse with the new throttle body now that I've driven it a few days.

Knuckle Dragger
02-28-2013, 11:10:31 PM
TB conectors have issues. I'd try filling the conector with dielectric grease and trying it again. TB takes care of 90% of them, the grease takes care of most of the ones that still have an issue the conector is the last stop.

meangreen73
03-01-2013, 07:18:28 AM
TB conectors have issues. I'd try filling the conector with dielectric grease and trying it again. TB takes care of 90% of them, the grease takes care of most of the ones that still have an issue the conector is the last stop.

The connector was changed with the throttle body as well as the ground and I used dielectric

68400BIRD
03-01-2013, 09:09:40 AM
I can't help with the p1516 problem. But the guage pods have problems in these trucks. If you do a search there is someone who rebuilds them for a good price. (If needed) I also have a 2003 and the guages have acted up 1-2 times in the last five years. I shut off the truck and restart it and the problem goes away. I think my main problem was the truck being driven oncea month in the winter and being in minus temp weather. If the guages continue being a problem let me know and I can find the info that you need.

camarochevy1970
03-01-2013, 09:13:42 AM
Which ground did you check?

dwright406
03-01-2013, 10:19:01 AM
THIS^^^ is the reason I sold my 04 Hummer H2

the best I could do was clean the MAF with the appropriate cleaner, clean the throttle body with the appropriate cleaner & make sure the air filter is not restricting flow

MY CEL was always a "voltage variance between the pedal & throttle body"

I finally sold the thing because it was obvious the truck was retarded

I had the same issue with my '02 Trailblazer recently, it kept going to reduced power and coming up with the "voltage variance between accelerator pedal & throttle body" code.
I chased wires and cleaned connections for a while, then I picked up another accelerator pedal out of the junk yard and swapped them out, which fixed the problem.

The bushing in the accelerator pedal which the pedal pivots on wore out and the rheostat was losing contact and tripping the CEL.

jgaulin
03-02-2013, 07:38:25 AM
check grounds g103,g104 on the back of both cyl heads. also have had some problems caused by mice getting under the underhood fuse block and chewing on the wiring. also your truck has a tac module to control the throttle body,it is bolted to the left side of the firewall.