Hello!

First time poster here. I have a question.

The vehicle is:

1987 Chevy van Sport 30 (1-ton) class C 21ft RV with a Chevy 350 Engine 5.7 l PGM-FI (fuel injection, first year of T.B.I.).
3-speed trans. with cooler.

It has a brand new rebuilt transmission, including a brand new kickdown solenoid inside the transmission. I can see the orange wire is connected properly.

The issue is that it will never kickdown (even when the gas pedal is floored).

My shop manual's electrical diagram indicates there's a "kickdown relay" somewhere.

Where is this relay? I don't seem to have any switches on my gas pedal assembly. Is it missing?

Also, is the transmission kickdown solenoid activated by the kickdown relay switch only? Or does it rely on other sensors as well, such as the speed sensor?

Thoughts?

Otherwise, the transmission downshifts properly at stops and such. Seem to work fine.

Thank you for your time! Cheers!

Ben

 

Hi again. My information was flawed. Every dealership that I called is either refusing to assist or they say that the techs that were able to work on these are all retired!
But most importantly, the information I managed to squeeze out of them is not right. It's not a kickdown switch at all, it's a relay (controlled by pin A7 of the engine control module).
As you know, a relay is controlled by electricity, not a human hand.

So now I am following colored wires inside the engine compartment and the cab. Fun stuff!

 

Also, these 3 things are under the driver's seat. I am assuming the big shiny box is the Engine Control Module?

 

Progress! While looking for wires of various colors I did notice something funky.

The throttle cable is too long!

When the gas pedal is floored (WOT), the throttle positioning sensor is not fully "engaged". This probably means that the computer can never tell if I am trying to floor it. Not to mention I am probably not getting engine full power, ever. Wow...

 

I FIXED my issue. Throttle cable had too much slack. The TPS was never fully engage when I floored the gas pedal.

Now the computer knows when the gas pedal is floored, and the computer now "activates" the kickdown relay.

Yay.