Hey guys, new to this forum and seeking some help!
I have a 2001 c3500hd with the 8.1L. I have codes p1220 & p1221. I changed the Tps sensor but still have same codes. I decided to check the tps sensor voltage just because it’s an aftermarket part. Hoping I did this right..here are the readings I got for the tps….

tps sensor #1
WOT - .35v
IDLE - 4.01-4.02v
CLOSED - 4.55v

TPS # 2
would have same reading of 4.85 through out the movement of the throttle body. It wouldn’t change at all! My question is: Is this normal? Does anyone know what the voltage should be??
any help would be very much appreciated 🙏🏽

 

If you were to look at the voltage waveform for the 2 TP sensors, they are opposite one from the other.
It would seem that TPS #2 is open for whatever reason.