4l80e transmission shift issues

[Battousai3135]

I have changed shift solenoids and the transmission seemed better however it still won't shift through the gears properly and I am trying to figure out what I should do to get it back to normal if anyone has any information about this transmission and these types of issues I would greatly appreciate your input thanks

 

[Jaryd]

Have you hooked a scanner up and read the trans codes? If not that’s were you should start this time

 

[Battousai3135]

No don't have a scanner it's a 93 will odb1 even give me trans codes

 

[ak diesel driver]

Make sure the TPS is adjusted properly

 

[Battousai3135]

It is in a GMC 3500 vandura boxvan and it has the 4.3 v6 in it the throttle position sensor is adjustable?

 

[Stoney]

Could you be more specific as to what you mean by it won't shift through the gears properly... And I was curious about the throttle position sensor also when you questioned it.

 

[ak diesel driver]

a lot are

 

[Rockabillyrat]

ODB1 can be tricky because alot of times it doesn't set codes. You really need to get a scanner on it and check a few things. Think of it as a old mechanical transmission when it comes to diagnosis. TPS is your driver load input. The electronic version of a throttle valve. Makes sure the voltage is around .5v at closed throttle and 4.5v at WOT. Then sweep it to make sure it doesn't drop out between closed and open throttle.

Next test the speed sensors. Which is the electronic version of govenor pressure. I believe in a 93 you have a input, output and vehicle speed sensor. The computer uses data from all 3 to control shifting.

If they both test good. Next check all your powers and grounds. Test amperage flow of your solenoids. Confirm good line pressure, and if nothing points to a issue. Then it time to tear into it.

 

[THEFERMANATOR]

The TPS is not adjustable on a 4.3l. You really need to get a scanner on it and see what is going on. Throwing parts at it is a sure way to not fix it, and many times make it worse. The 4l80e is a fully electronic transmission and needs to be diagnosed as such. It could be a bad TPS, MAP sensor, EGR valve going full open, trans temp sensor, coolant temp sensor, and on and on. Throwing parts at it can really screw you because some parts are different for 91-93 vs 94-02. And we need detailed descriptions of what is happening to even begin to help you without a scanner.

 

[Battousai3135]

I have done

ODB1 can be tricky because alot of times it doesn't set codes. You really need to get a scanner on it and check a few things. Think of it as a old mechanical transmission when it comes to diagnosis. TPS is your driver load input. The electronic version of a throttle valve. Makes sure the voltage is around .5v at closed throttle and 4.5v at WOT. Then sweep it to make sure it doesn't drop out between closed and open throttle.

Next test the speed sensors. Which is the electronic version of govenor pressure. I believe in a 93 you have a input, output and vehicle speed sensor. The computer uses data from all 3 to control shifting.

If they both test good. Next check all your powers and grounds. Test amperage flow of your solenoids. Confirm good line pressure, and if nothing points to a issue. Then it time to tear into it.

 

[Battousai3135]

I have replaced both speed sensors and tested TPS replaced force motor and shift solenoids and manifold

 

[THEFERMANATOR]

I have replaced both speed sensors and tested TPS replaced force motor and shift solenoids and manifold

How did you test the TPS? Back-probed it or connected a scanner? You NEED a scan tool of some sort, otherwise stop throwing parts at it, and take it to somebody with one. Also remember new parts does NOT = good parts. With today's part's quality(or lack there of) many new parts are worse than the failed ones they're replacing. Firing the parts cannon almost ALWAYS creates more problems instead of fixxing them. With a fully electronic trans you must see what is being seen and commanded to work on them.