Ill try to make this as short as possible. Bought a 2003 sierra a week ago. Test drove it and all fine. Pay for it and go to back out of the driveway and get shift range inhibited. Only flashed for a second and then in reverse and on my way. I automatically thought nsbu or ignition switch as I had both problems on a previous truck. On the 4 hour drive home, twice while the cruise was on at 65mph it felt like the truck went into neutral, and the underline under the PRNDL started flashing, then back into gear and driving normal. So I get it home and change the ignition switch and nsbu to see if I get lucky. Go on a test drive and all seems fine, until I push it a little harder and on the 3-4 shift it drops to neutral and I get shift range inhibited again. Drive home it feels like its in 4th gear the whole time. Get it home and disconnect the battery and check the harness on the nsbu and the rest of the tranny harness for rub spots, but nothing I can see. Start it up again and I get the shift range inhibited, and no reverse and only 4th (or maybe 3rd) in forward. Any ideas before I ship this thing to a tranny shop?
LB7: New truck is driving me nuts with shift range inhibited
- Thread starter stricker_76
- Start date
Sorry, knew I forgot something. When it kicked into neutral on the 3-4 shift on hard acceleration it kicked a p0700 and a p0872. Every other time, as well as how it sits now, no codes.
need a better scanner to read what the p0700 is kicking. thats the TCM telling the ECM to set the CEL. The TCM has codes in it your scanner cant read
Sounds like a draggy E shift valve. If so, might indicate trash in the pan and sump filter. Try a new spin on and see if you get lucky.
I've got a spin on ordered and my fingers crossed. lol. Is there a way to reset the tcm codes, I assume my scanner doesn't if it can't even read them.
Ok, so I changed the spin on lastnight. Had a no name on there, and isn't there supposed to be a magnet on top? Guess ill have to find a new one. Fluid was clean, and cut open the old filter and nothing suspect in there either. Hooked up a better scanner I borrowed from work and no codes, but the battery has been disconnected for a few days. Drove it for an hour and no problem other than the _ disappearing from under D for a few seconds, but didn't affect the driveability at all. Start it up this morning and it goes in drive no problem. Put it in reverse and the underline starts flashing and goes out, no reverse and clunks into 3rd or 4th when in D. Threw 2 transmission codes, P0763D Shift solenoid C electrical and P0768D Shift solenoid D electrical.
So I guess im dropping the valvebody this weekend. Does it make sense that the shift solenoids would drive fine but make it throw these codes first thing in the morning when put in reverse?
If mike or someone doesn't reply on here soon, I'd call Mike or Evan and pick their brain for which way to head with it.
Good luck and be sure to update with what you find. Sorry you're having issues with a new (to you) truck.
Good luck and be sure to update with what you find. Sorry you're having issues with a new (to you) truck.
Start checking voltage at the TCM then follow wire 231 down to the trans. If you're not good with electronics; let a pro diagnose it. You will need a wire diagram with pin outs and a DVOM.
I'm not great at wiring, but following wires and checking voltages I can do. At least I'd prefer to give it a shot myself this weekend before I send it to a shop. Where can I find a copy of the wiring diagram?
Close enough for what you need. The '05 will have a G solenoid so just disregard it.
Well I got busy and didn't have time to dig into it so sent it into a tranny shop. Sure enough, messed up wires back by the tranny. Guess the only reason I didn't see it is cause the previous owner noticed it and decided to electrical tape it without fixing it. Gotta love it!