Transmission codes P0740,P0785, P1860
 

Ok so I was driving down the highway about 65 mph with cruse control on and out of nowhere my engine started revving up to red line. So I hit the break to kick it out of cruse and everything was running fine until a mile down the road I lost all guage functions. The truck was now in limp mode(stuck into 3rd gear) I had no power didn't know what was wrong I turn around and drive home(about 10 mins away!) I get home and I find wires from my ECM half way burned apart. I take a code reader and check the codes:

P0740-TCC CIRCUT MALFUNCTION
P0785-SHIFT CIL. MALFUNCTION
P1860-MANUFACTURE CONTROL TRANSMISSION

Things Iv Done To try to fix the problem
1.I repair the burnt up wires by soldering them and using marine grade shrink wrap.
2. Checked all of the fused with a multimeter.
3. Replaced the ignition switch.
4. Fixed the cause of the burnt up wires.(hose from the exhaust manifold to the air injection pump)

I swear this has to be an easy fix. What could it be has anyone else seen this problem. It seems like every step i take forward im moving 3 steps back. :icon_starwars:

Oh and the transmission in the vehicle was rebuilt about a month ago!

If you threw a PO740, I'd take it back to who ever rebuilt it. That's an internal issue of the valve body.

MrJP we have figured out the problem after weeks of trial ans error we found that it was our guage cluster that was causing all of the trouble! The guage cluster wasnt throwing power to the transmission causing it to throw the P0740 code. Thanks for the insight it actually helped us diagnose the problem My Blazer now drives like a champion no issues!