Computer issues screwing up O/D in a 4l80e

[cuervo]

I had an issue with lost of first and O/D. 91 3/4 suburban with 4l80e / 350


I had the 1/2 shift solenoid and the manifold pressure switch change out and codes cleared and it was working fine. Then about 3 months later is started doing the same thing again.

The codes this time are just for the 1/2 shift solenoid. The trasmission shop is telling me it is the computer now. He says the 91s have had issues in he past.

I don't know enough about the computers to say so I'm asking here.

The tech says they have check all the other solenoids and have check each wire going from the computer to the transmission and says they are all fine.

??

 

[nvrenuf]

What's it doing?

 

[cuervo]

What's it doing?

Same as before, starts in second and wont go into O/D. I know the 1/2 solenoid was bad but the O/D and him saying computer has me worried. I figure it has something to do with the TCC plunger solenoid leaking pressure off.

I made sure to ask the guy, if you change the computer this will fix the overdrive issue right? He said yes, if he replaces the computer and it does do anything he's gonna eat the cost.

 

[nvrenuf]

I made sure to ask the guy, if you change the computer this will fix the overdrive issue right? He said yes, if he replaces the computer and it does do anything he's gonna eat the cost.

Good move.

Sorry I don't have any real tech to offer but I was curious, my old crew cab did some crazy junk from a piched injector wire but it never disabled o/d. (my problem was convertor lock up all the time)

 

[cuervo]

Good move.

Sorry I don't have any real tech to offer but I was curious, my old crew cab did some crazy junk from a piched injector wire but it never disabled o/d. (my problem was convertor lock up all the time)

Was yours disel? I have found out from my reading that if a disel is getting a bad TPS it will lockout of OD as well.

 

[nvrenuf]

Mine was a 91 v3500 w/ 350/4l80e/blah/blah...

 

[cuervo]

Mine was a 91 v3500 w/ 350/4l80e/blah/blah...

Yup, same as mine, well mine is 2500.

 

[cuervo]

Well, got my Suburban back today. He changed out the 1/2 solenoid and the computer and it's working fine. Even with 35s not having O/D with 4:56s was kind of a pain.