transmission modulator

[vzfox]

Simple question....

 

Does the transmission modulator (small diaphram that hooks to the transmission with a vacuum hose going to the carb) have anything to do with reverse, or only forward gears?

 

1979 GMC K1500 4x4...350 engine...350 turbo tranny.

 

The reason I ask is, the modulator diaphram is leaking tranny fluid when it isnt suppose to have fluid running through it at all. I am going to replace it obviously, but my reverse gear has started acting up....you can feel/hear it kick into reverse, but the truck wont move. Maybe the leakage might have something to do with this problem??

[vzfox]

Any kind of help would be MOST appriciated.....thanx.

[GM-Tech]

The modulator is used to "modulate" or control shifts based on throttle opening. It would not cause the loss of reverse or any other gear.

[ChevyTech007]

Could be low on fluid. If the diaphragm in the modulator is leaking it can suck trany fluid out of the trans.