1997, 4.3L 4x4. Transmission rebuilt in 2008. Nothing but oil changes and brakes since.

Key won't switch to "off" position, transmission in limp mode (2nd or 3rd gear only) and frying the transmission fuse (#24). I put in a new ignition switch and still have the same problems. Codes are reading p0740, p0785, p1860, which I thought meant ignition switch. Any ideas? I'm sick of catching rides in to work at 6am with the girlfriend. Thanks for any help you can give me.

One other thing, when I first plugged the code reader in it was reading p0147, p0740, p0753, p0058, p0785, p1860. now I'm only getting p0740, p0785, p1860.

 

I am having the same problem on a 97 4wd. When I research the P1860 code it says that it is caused by a DTC P0560 which is defined as being that the PCM detects either a low voltage or high voltage spike. I had a suspect battery so I swapped out with battery from my Silverado and the same thing happened in about a two block test drive. My key won't turn off either until I clear the codes and then it will.

I had replaced the starter solenoid in October which is the only thing that has changed on this vehicle in the past year. About the same time the transmission started acting up it had also not wanted to engage the starter but if I reshifted out of and back into park it usually started right up so I wrote it off as a neutral safety switch going bad but now I am thinking it may be that I got a bad solenoid that is causing the voltage spike. don't know if that helps you but if anyone else has an idea on if that could be the problem I would appreciate the help. Mine is just my back up ride but it is irritating not to have it work right when I want to use it.

Good luck with yours.