'77 throttle pedal position sensor.

[RADustin]

I bought a '77 crewcab(just the cab, silverado trim) and while disassembling it I noticed it had a little linear potentiometer the bumped against the throttle pedal. I assume this was some sort of early style TPS.

Is this what it is? and what was it used for?

 

[1987 GMC Jimmy]

I bought a '77 crewcab(just the cab, silverado trim) and while disassembling it I noticed it had a little linear potentiometer the bumped against the throttle pedal. I assume this was some sort of early style TPS.

Is this what it is? and what was it used for?

If it's what I think it is, then I'd answer sorta because it senses accelerator pedal position, but it's not for the throttle. It sounds like the kickdown switch for a TH400. When you stamp down on the pedal trying to pass someone, that switch tells a solenoid in the transmission to kick it down to second gear.

 

[HotRodPC]

Turbo 400 kickdown activation switch. Pretty much just a WOT switch. Send a signal to the solenoid in the transmission. Should have an orange wire going to it.

 

[RADustin]

that's it. I thought turbo 400 used the vac modulator for kickdown??

 

[Honky Kong jr]

that's it. I thought turbo 400 used the vac modulator for kickdown??

Nope electrically activated kick down. I used to wire it to a relay from the red button on my shifter. All you need is a momentary switch. I used a relay and switched the ground' the wires in shifters are pretty small.

 

[RADustin]

alright.

Makes sense. I'm learning...slowly.

Thanks Gents.

 

[74 Shortbed]

that's it. I thought turbo 400 used the vac modulator for kickdown??

It does have a modulator but it has to do with shift points not the kickdown.

 

[HotRodPC]

that's it. I thought turbo 400 used the vac modulator for kickdown??

The governor and vac modulator determine shift points. The throttle switch will override both.