Shift Timing Solenoid

[Squigmaster]

I have a 2002 Silverado 5.3L with about 64k miles on it. I just bought the truck about 6 months ago and i've had no problems with it until now. I was cruising about 20mph last night and my Service Engine light came on. I noticed that the shifting was off from there on out. I had a friend check the code, I believe it was PO785 / Shift Timing Solenoid. How big of a deal is this? Thanks for the help!

[maxwedge]

Welcome to AF. The solenoid pak is attached to the valve body, pan must come off. Cannot tell what your capabilities are in this area, you must decide.

[j cAT]

Originally Posted by Squigmaster

I have a 2002 Silverado 5.3L with about 64k miles on it. I just bought the truck about 6 months ago and i've had no problems with it until now. I was cruising about 20mph last night and my Service Engine light came on. I noticed that the shifting was off from there on out. I had a friend check the code, I believe it was PO785 / Shift Timing Solenoid. How big of a deal is this? Thanks for the help!

your problem is most likely wiring or connector related. check wiring going to transmission for chafing short to frame or trans housing also connectors to trans for wiring defects if none found will need to have transmission repair as could be internal this is a saftey limp mode for transmission if something shorts or opens on control circuit of transmission... at least you know whats going on eventually it will get worse.

[Squigmaster]

Thank you guys for your replies. At least I now have an idea what to look for

[99silveradols]

Hi there. I don't know if you have resloved this yet, but I had the same thing. Out of the blue the SES light popped up and the code was the same - P00785. Fortunately I have a warranty on my 99 so I had the dealer check it out. The problem is not with the shift solenoid, but with the ignition switch, of all things. It is a fundamental wiring issue that can set any number of codes, and send people on (expensive) wild goose chases.

You should have it checked out before you begin spending time/money on a potential red herring!

Good luck!