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transmission modulator

vzfox

By vzfox
June 4, 2006 in Ask A GM Technician

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vzfox

Enthusiast

vzfox

Posted June 4, 2006

Posted June 4, 2006

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

Enthusiast

vzfox

Posted June 6, 2006

Author

Posted June 6, 2006

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

GM-Tech

Senior Enthusiast

GM-Tech

Posted June 6, 2006

Posted June 6, 2006

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

Enthusiast

ChevyTech007

Posted June 7, 2006

Posted June 7, 2006

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

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