I have a 2003 Yukon XL SLT quadsteer 2500...love my truck...really tired of seeing the check engine light. I keep getting the P1516 code. It used to just do reduced engine power and keep driving. Then it kept getting worse. Replaced pedal sensor, throttle body module, thoroughly cleaned throttle body, checked all wires for shorts. Nothing has helped. I've had 2 different people look at it, one is supposed to be one of the best mechanics in town. Its gotten to the point where he just lets me drive it home with no charge to see if what he did will work! Because the fixes always seem to fix it for the short term but then it will code again in a day or two and then it will continue to get worse and worse.
The latest problem besides doing reduced engine power is that it will 'stick' in acceleration. I push the gas pedal and the car just takes over. It accelerates by itself, the rpms idles at 1.5-2, i can drive down the road without pushing pedal, it will continue to rise in speed and rpm without pushing pedal, i have to hold brake down hard when stopped, transmission temp rises if idles too long, and when put in park it will rev up to at least 3 rpms. sometimes it will code and sometimes it will just drive like this. the code still keeps coming up as only p1516. we've even changed the pedal sensor and module again just to make sure the ones we put on weren't bad.
I'm desperate here. i know this can't be good for my transmission but we have literally done, fixed, cleaned, or changed out every part of the throttle system and its only getting worse. its almost impossible to drive now and its my only vehicle.
first thing in the morning is worse. i can let it warm up for 30 minutes and it will still code several times before i get out of the neighborhood. seems to like it when the engine and transmission temp gauges say they are warmed up but even then after driving for a while the acceleration will start to stick again. the engine light also shuts itself off by the afternoon regardless of how its driving.