[Caleb55]

I'm about ready to lose my mind trying to figure this out. What I have is a '95 k2500 with a 350 and 4l80e. I bought this truck from my work a couple of months ago. The tranny was rebuilt about 30,000 miles ago. When I bought it from work it only had second gear. Ran the codes and found I had bad shift solenoids. Swaped both of them out and the trans was fine. The other day things went crazy. I was going along at 60 mph when the truck started to downshift on it's own. RPM's went way up and so on. The speedometer started jumping around and stuck on like 70. Tach slowly went down to 0. Odometer quit working as well. I can shut the truck off, and sometimes it will go fine, other times it will do these same thigns again. I ran the codes again and got a 68 and 83. I know the 68 is an overdrive ratio error and the 83 is a TCC seloniod circuit fault. But what I dont know is what those actually mean. I'm thinking it's an elctrical issue, but need some help

 

[Tracy]

My truck had similar codes. The problem was a shorted tcc solinoid. Problems started the same way as yours because the trans defaults to 2nd gear. The truck would work fine if I turned it off and turned it back on, it would shift through the gears just fine until the trans TCC locked up then only 2nd gear. The trans in diesels (depends on axle gearing) will only lockup at 55mph or above so it was very easy to recognize that there was a problem with the TCC solinoid, it would work fine till 55mph then it would default to 2nd gear. I think the trans has a little different programing between the gas and diesel. The gas trans programing may make it a little harder to recognize, it may have lockup at different speeds and gears. Just a idea but I would try seeing if you only have problem when the TCC locks up.

 

[Caleb55]

Hey guys I was told today that it could be my ignition switch causing these problems too.