Reduced engine power 2005 gmc

SOURCE: 2001 GMC YUKON REDUCE ENGINE POWER ON MESSAGE BOARD

The following is a post from another site. I had the same problem and this worked for me.

Hello all,

I just wanted to share with everyone with the problem that I had withmy 2003 1500HD Crew Cab with 6.0 Liter. My truck would go into reducedengine power off and on. Sometimes one a week, sometimes 5 times on a20 mile trip. My problem was a broken wire on the plug in going in tothe throttle body. In the picture is the plug in that had caused me allof my pain and grief....... My problem was very intermittent and washard to diagnose. I started vehicle and with all codes clear. I wiggledthe wiring harness in the picture and vehicle spit and sputtered,throwing it into reduced engine power mode, and then smoothed out to asmooth idle. I disconnected the plug and pulled wires out of plug endand found a broken wire. Mine was a brown wire with white stripe. BUT,what was interesting, was that this vehicle had apparently had the smaeproblem with previous owner, becuz there was another wire (yellow wire)right beside the one that I found broken already soldered up and tapedfrom where it had apparently happened before. This was my problem andnot my truck is running great, and actually even idles better thatbefore. Hope this helps with any problems that anyone else is having. Iknow this problem can be very irritating.

http://i184.photobucket.com/albums/x191/bunchtst/BrokenWire.jpg

SOURCE: SES light then Reduced engine power light, loss of engine power

Hi It me Mohammad Siddiq my dear. First of all it will be wise of use to take your vehicle to a dealership or any other fully equipped w/shop. They can better tell you what the fault your vehicle has. But at the same time if your friend has the same model vehicle so you can exchange some parts with that vegicle, e.g., Mass Air Flow or TPS (Throttle Position Sensor) and can check your vehicle. These parts do not need to be programmed with scan tool. Just Simply replace these parts and switch on the ignition and wait for 01 minute, then switch off for 30 seconds and then start the engine. Now road test your vehicle, if no SES light or reduced power then there was fault with the part/s replaced. So Return those parts and now you must replace these parts with new or used ones. Anything else I may be contacted on my yahoo id [email protected]. Thanks. I am an auto technician and working in a GM dealership in Saudi Arabia. I am from Pakistan.

SOURCE: I have a 2005 GMC 2500HD code P1516, already

The Throttle Actuator Control (TAC) / throttle body type trouble codes, may be caused by a loose wiring crimp at the throttle body connector, or a broken throttle body circuit.Inspect all related throttle body terminals for a loose wiring crimp. The loose crimp may be difficult to find, and the poor connection will be between the terminal and the copper strands of the wire. Wiggle test the individual throttle body circuits to see if the concern can be duplicated.
Inspect the related circuits for broken wires inside the insulation. The outer wire insulation may look fine, but the internal copper strands may be partially broken. Breaks in the wires usually occur within 1 to 4 inches of the throttle body connector. Wiggle testing may also induce a trouble code to set.
On C/K trucks complete SI procedures for voltage drop on grounds G103 and G104. Grounds G103 or G104 may be loose or corroded. If a terminal crimp or a broken wire has been found, repair or replace only the circuits involved. There is a throttle body pigtail connector available through GMSPO, post back with what you find.

SOURCE: service engine soon and reduced engine power

disconnect batt. for 30 min. then reconnect,if no problem exist the lights will go away

SOURCE: 2002 gmc envoy check engine and reduce engine

typical causes: dirty air filter, clogged up catalytic converter