Hello all new here with a trans issue,
03 1500 4wd 5.3, rebuilt 4L60e recently, all worked fine until a couple weeks ago, the thing has started shifting strange, lite throttle all shift normal, above 15-20% throttle it wont shift from 1-2 until 4500 rpm, will hold od and lockup fine until you break that 15-20% throttle then drops lock up and crazy shift from 4-3-4-3 and so on, if you can stay below that throttle percentage all behaves normal. Am I going the correct way by thinking TPS is bad, engine runs fine and all seems normal, now charging AC the day and trying to hold engine at 1500rpm it wanted to hunt a fair bit.
Thanks for any help.

 

First check for codes. Even if the MIL isn’t on, codes can be stored. If any code(s) begin with P07 then they are transmission codes and I would recommend you take it back to the transmission shop as it may be their fault.

 

I did the transmission myself, there is no way to check for codes, apparently I have other issues, the data link will not cvommunicate.

 

Update, replaced throttle position sensor and the accelerator pedal position sensor, it did help, but still not right. Believe I have the Data link issue figured out, pretty sure the fuse is blown, will find out tonight, truck also will not adjust the air flow position for the climate control, the AC compressor will only run if the button is off, and the power driverside seat functions backwards on the for and aft control, iam guessing that is the motor wired wrong, trans still does not shift properly above 20% throttle, and will not stay in overdrive if I get above that throttle position, if I get data link to work I am going to do a force relearn on the transmission as well.

 

The power supply at the OBD port is from the lighter fuse (may be labeled aux power, but either way it’s a 20A) in the engine bay fuse box. If a code reader is powering on but unable to read codes, it’s a problem with the data circuit. If it’s not powering on, jumper a test light between pins 16 & 4 (google GM OBD2 port pin out for a diagram). If it doesn’t light and the fuse is good, the ground circuit on pin 4 may have an open.

 

Thanks @Gumby22 I will check it tonight, all solenoids were done when i rebuilt trans, worked fine for a little more than a month then started the screwy shifting and was getting worse until I changed TPS and APPS, that helped but it still does it, I will if there are any codes, thing is weird