Question

I have a 2002 GMC Yukon Denali xl 6.0L and I am getting codes P1515, P1120, and P1221. I took the throttle body off and cleaned it, replaced the tps and pps sensors and today I replaced the throttle control module. Do you have any advice on what to try next? Also I should tell you what it does, it use to only do this once in awhile now you can't drive it at all. When you start it up it goes straight into reduced power mode and when you step on the gas it will only increase in Rpm by maybe 200 rpms. Do I need to relearn the pcm? Any help would be gratefully appreciated. Thanks

Answer 1

P1515 Throttle actuator control  throttle position

P1120 Throttle position sensor 1 circuit

P1221 Throttle position sensor 1-2 correlation

P1515 and P1516 either time when this code appears what to look for is poor contact, P1120, and P1221 it is no connection. You may  have to replace the pigtail of the throttle actuator motor

​ 

Here a P1515 or P1516 that was set what happen is the locking tabs where not making contact,  as it was broken and missing, To prove the problem zip ties where use to hold and make contact with the connection, The problem solved.