2015 chevy malibu 2.5 automatic 167.593 miles p2122,p2138,p2128,p257f,uo100,the p2138 appears twice,i am using a INNOVA3100,the information window on the car reads engine power reduced,hood open,service stabilitrac,check engine light,taken to the chevy dealer with the engine power reduced and stabilitrac trouble,you could turn of the car and start it again it would clear it,the dealer replaced the the accelerator pedal but they do-not show how they fixed the stabilitrac,few days later reduced power and stabilitrac kept coming and going,both are staying on now,i can clear it but it comes back,i replaced the pedal again (GM part) it did not help,i replaced the whole throttle body (GM part) no change,i also noticed the 2nd fan not turning on tested the fan its good tested fuses and relays ok,checked all connectors and wiring,i have good continuity from the ECM too the pedal and from the pedal back too the ECM,one sensor lead i have 1.2 volts ign off ,1.2 volts ign on,1.2 volts car running,pressing the pedal i get1.6 volts,the other sensor lead i get ign off 0.1v, ign on 0.7 v,car running 0.7 v,pressing the pedal 0.9 v,are you suppose to have voltage on the sensor leads?GM has a recall on 2016 too 2018 they say check the knock sensor wiring or sanity of the EMC. thank you
Please don’t double post, thanks.
That sounds familiar.
1st, when a code related to the sensors in the ETC (electronic throttle control) circuit get triggered the computer turns off things like stabilitrac because it uses the ETC sensors in the stabilitrac control system.
Fix the ETC issue and the computer turns stabilitrac back on.
Those APP sensors in the "gas pedal" work opposite of each other.
The computer provides a reference voltage signal and one sensor returns a high voltage signal when the pedal is up and the voltage signal decreases as the pedal is depressed.
The other sensor operates the opposite. It returns a low voltage signal when the pedal is up and the voltage signal increases as the pedal is depressed.
Sometimes there's even a 3rd sensor with a very narrow (0.1) voltage range between up and fully depressed.
But the computer has to have an accurate voltage return measurement from all of the APP sensors.
Afterall, that's the failsafe redundancy built into the "gas pedal". If those voltage signals don't correlate with the computer's known voltage values the computer wastes no time throwing an ETC related DTC (code), (your Malibu is throwing 3 of them) and the computer goes into "Power Reduced Mode".
Chevy has been having an issue with this for years (more like decades) and when I read your post I remembered a similar issue with a chevy. The guy replaced the APP, TPS/Throttle Body and it still kept throwing a P2138 code and going into reduced power.
So as usual I first pulled the codes and did a search for related TSBs. Sure enough, there was one related to a P2138 and their IP (instrument panel) to Body Harness Connector.
I think it was behind the kick panel by the driver's left foot. It had a little corrosion from water intrusion and we were able to clean it up. Problem solved.
Frankly when I read your post I couldn't believe by 2015 Chevy didn't improved that connector, So, I did a TSB search (again) and sure enough, they still haven't addressed the connector's integrity.
So here's the TSB's link and a screenshot...... might be worth considering
https://static.nhtsa.gov/odi/tsbs/2015/SB-10028831-8729.pdf
Models: 2005-2015 GM Passenger Cars and Light Duty Trucks
Well I would take it in for the recalls first it could very well be a bad main computer very typical on that model and will do all those things
