ARAMP1
Member
I have approximately 200K miles on my 2011 Yukon XL 2500 (6.0L/6L90E). As the title says, I'm getting a P2138 code with reduced engine power. I've seen a couple threads on this, most recently THIS ONE.
For troubleshooting, I followed THIS video. Resistance was over 5Ω in both low reference wires and I found one of the wires frayed so I went ahead and replaced all six wires to the throttle pedal (new wires in the harness, new plug and repined with new Delphi connector). Now both low reference wires (purple and brown) are exactly 2.2Ω (under 5Ω) and both the 5V reference wires (tan and white/black) are exactly 5.1V (over 4.8V). I replaced the throttle pedal for good measure.
One odd thing, my brown and white/black wires were swapped around from this video. I went ahead and swapped them around to match what was in the video to see if that was the fix but it didn't change a thing. Since I had replaced all the wires and plug, I still had the old one. Then, I found this diagram online which is what mine is...so I didn't accidently swap those wires.
I had a lot of the plastic wire loom under the hood brittle and missing so I decided to replace the six wires and connector from the ECM to the throttle body. The throttle body was gunked up so I replaced it to included a new TPS.
I've seen the TSB related to water intrusion and the P2138 code. I do have water intrusion on the driver side. I've cleaned out all of my sunroof drains and have drained water in them verifying they are clear. I just recently pulled the GPS antenna and put some RTV around the opening though it hasn't rained since doing this. I remember reading a thread here where someone had a leak around a windshield/body seam. I haven't explored that yet.
So now I'm kind of at a loss. Both throttle position signals are still off from each other.
I've checked all circuit breakers and all relays appear to be fine. At this point, I guess I'm just throwing parts at it to figure out what will fix the reduced engine power and P2138 code. I'm trying to figure out what module under the dash may have gotten corroded due to water intrusion. Maybe a bad ECM (the vehicle starts and idles fine)? Appreciate any ideas or suggestions for troubleshooting.
For troubleshooting, I followed THIS video. Resistance was over 5Ω in both low reference wires and I found one of the wires frayed so I went ahead and replaced all six wires to the throttle pedal (new wires in the harness, new plug and repined with new Delphi connector). Now both low reference wires (purple and brown) are exactly 2.2Ω (under 5Ω) and both the 5V reference wires (tan and white/black) are exactly 5.1V (over 4.8V). I replaced the throttle pedal for good measure.
One odd thing, my brown and white/black wires were swapped around from this video. I went ahead and swapped them around to match what was in the video to see if that was the fix but it didn't change a thing. Since I had replaced all the wires and plug, I still had the old one. Then, I found this diagram online which is what mine is...so I didn't accidently swap those wires.
I had a lot of the plastic wire loom under the hood brittle and missing so I decided to replace the six wires and connector from the ECM to the throttle body. The throttle body was gunked up so I replaced it to included a new TPS.
I've seen the TSB related to water intrusion and the P2138 code. I do have water intrusion on the driver side. I've cleaned out all of my sunroof drains and have drained water in them verifying they are clear. I just recently pulled the GPS antenna and put some RTV around the opening though it hasn't rained since doing this. I remember reading a thread here where someone had a leak around a windshield/body seam. I haven't explored that yet.
So now I'm kind of at a loss. Both throttle position signals are still off from each other.
I've checked all circuit breakers and all relays appear to be fine. At this point, I guess I'm just throwing parts at it to figure out what will fix the reduced engine power and P2138 code. I'm trying to figure out what module under the dash may have gotten corroded due to water intrusion. Maybe a bad ECM (the vehicle starts and idles fine)? Appreciate any ideas or suggestions for troubleshooting.
