simman22

iTrader: (25)

After hours of searching I figured I would just ask here since I couldn't find an answered post on someone with the same problem. I swapped my old 2002 4.3 and a 1997 4l60e (rebuilt) into a 1981 C10. I got all of the engine harness, engine mounted, and PCM changes made.

It runs beautifully but when you put it in drive it stays in second. You can manually shift it down to first but other than that it stays in second (park, reverse, and neutral work correctly). On HPTuners I can command 1,2,3,4 and TCC lock without an issue. The only code I am getting is P1810 sometimes. When the code isn't present it still does the same thing. So any help would be greatly appreciated.

simman22

iTrader: (25)

Internal pressure manifold was the culprit, changed it and all is good.

bbond105

Those things can create some strange problems.

iceburgh

explain more please....having the same issues but don't know what to do with internal pressure .
I have the intune and need to get the tranny working

coryforsenate

iTrader: (1)

If you think it might be a bad manifold pressure switch, it's a cheap part and only requires a pan drop to replace. It might be worth giving it a shot even if you're not sure it's the problem at $30 for the MPS, AC Delco part #24215111 for the 4l60e.

bbond105

The way you check for a faulty manifold pressure switch is with some type of scan tool. With the engine running you place the shifter in reverse, drive, 3rd, 2nd and low and check the scanner to make sure the manifold pressure switch scanner readings coincide with the whatever position the shifter is in. If they don’t match up then most likely the manifold pressure switch is defective.

simman22

iTrader: (25)

To go off of that (for anyone in the furture with this problem), I was able to command everything with HPTuners and it worked fine.