Trans shifting issues. 3800sc 4T65E-HD swapped 1988 gt. (Page 1/1)
deezil MAY 06, 06:47 PM
I have a 88gt with a swapped 3800sc along with a 4t65e-hd trans in it.

A few weeks back the car had the CEL come on and the trans went into limp mode. Nothing but 3rd and reverse. I stopped buy autozone and had the young guys there check the codes and it had these three below stored.
P0758
P0753
P01860

I made it home and had checked everything over after it cooled down some. I ran over every connector and harness around the engine and trans. I ended up pulling the battery for a look behind it as well and didn't see anything.
About that time the wife came home with dinner and I went inside and ate. a hour of so later I came back out to put the battery in and get the car in the garage. After starting it the CEL was off and the car shifted fine. I drove it for about 30 minutes and it was like it never happened. I changed the trans fluid and filter a few days later. Drove it for a hour and it was fine. The car had been sitting for several months in the garage since I had knee surgery first of the year.

Drove it to work today and then to do errands after work and it was fine for 2 hours.. Shifting was perfectly fine. I shut it off in front of my sons school and after restart the light was on and it was in limp mode again.

Same codes are up.

Any input you can give would be great.
Lou6t4gto MAY 06, 07:02 PM
sounds like one of the shift "Solenoids" is on the way out. the SET is relatively cheap. Or maybe a clip is loose on the solenoid
Steel MAY 06, 07:25 PM
Doubt all those solenoids are faulty.. I'd check the oxygen sensor fuse and cooling fan fuses to see if they're blown. Check the harness for rubbing or sliced wires. I had a similar issue a long time ago on my Grand Prix and it was a blown fuse.
deezil MAY 06, 07:30 PM
I went through all the fuses under the dash. I didnt see anything blown. I think I checked them 3 times. I don't know where anymore fuses would be.

I will check the wiring again I gave it a pretty good once over a few weeks back when it did it Maybe I missed something.
Lou6t4gto MAY 06, 07:42 PM
a fuse would NOT do it, fix it, then do it again
deezil MAY 06, 10:14 PM
I went over all the wiring. Everything looks great. No rubbing anywhere.

It *Looks* like I can pull the side cover to the trans in the car without dropping the power train.

The DS axle will for sure have to be pulled. .

I'll probably go ahead and order the harness as well. I see these are notorious for cracking the tabs off the connectors..

I'm not sure what year trans this is. Will the Tag tell me somewhere you think?

[This message has been edited by deezil (edited 05-06-2019).]