Hello everyone! This is my first post and I hope I’m in the right area. What I have is a buddies 93 c3500. Brought to me with a 68 code for slip. Checked all solenoids and basic stuff. Long story pulled trans and sent off to have rebuilt. What I realized after is that it’s a late model 4l80e(cooler lines in front and back on trans and 5 bolt bell housing). I talked to a very well known trans guy in Oregon and he said you can run this trans with the PROM on a 93 with that cleaning cycle and the lower freq. solenoid.
I am currently at a stop point. I have the rebuilt trans back in the truck and still getting a 68. I have replaced ignition control module, both VSS (input and output, it’s a 2wd dually), it has the updated wire harness on both truck and trans side. I’m getting good readings on my tech 2 for all basic inputs ie map, tps, vss, solenoids. The weird part I am seeing is with the RPMs, I have scoped both input sensor and what I think is the correct input for ESS (off dizy) I scoped all 4 wires off that and they are all showing a wave going up and bouncing about 3 times with about a 1v difference and then back down( not sure if this is a good wave for PCM. The wave form for ISS is a standard wave and very consistant. I am showing at idle a 300 rpm difference between ESS and ISS and the range grows the higher rpm is. The computer will command 4th but I never feel it kick and don’t see TCC lock up. If I force TCC lock up when pcm commands4th I get a shudder and about 500 on the TCC slip pid. This has me puzzled because one it’s not the original trans and not sure if this is all caused by the PROM. Any suggestions would be greatly appreciated! I love learning new things but I’m at my wits end with this one. I’m fixing to take the truck back to the trans shop that rebuilt it because I am leaning towards trans issue.
what do yall think?
thank you in advance
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