what does the orange wire from the trans connect to?

[Brianmontesa]

Had to pull the trans and motor now all back together and can't figure out where the orange trans wire goes...

Figured it went to the pedal, don't see anything.

Thanks!

 

[jdknech]

reverse lights?

 

[Brianmontesa]

I know it's for the kick down. But where does it connect? I don't believe it has anything to do with lights of any kind.

 

[jdknech]

the factory th400 trans has a vaccuum controled kickdown that is run off the injection pump... there are no wires for the kick down.. is it the orignal trans?

 

[Brianmontesa]

It's out of a 1985 diesel suburban.

 

[jdknech]

should be the same setup.. the kickdown is run off vacuum, the only thing electric is the back-up light switch.. do they work? or is it not shifting correctly?

 

[Brianmontesa]

The vacuum is all hooked up. Haven't started it yet. The sensor is just above the pan on driver's side I think. The trans shop that rebuilt it told me it was a kick down sensor. Like I said, don't see what it would hook to. Looks like I better look at the Chevy book tomorrow.

Thanks.

 

[Brianmontesa]

Maybe it's for cruise control? The suburban had it and I removed it all.

 

[jdknech]

what model truck are you working on? it should be in the TM's...

 

[Crash_AF]

It's for the kickdown solenoid. The switch is attached to the accelerator pedal. The vacuum actuates the kick down, but it's a constant source since the diesel doesn't make manifold vacuum, hence the solenoid.


Later

 

[patracy]

So much wrong information here.

The wire is as mentioned later correctly, the kickdown switch. However the vacuum line is not for kickdown. The vacuum gives the transmission throttle position. Wanna see? Disconnect the vacuum line and drive it a bit. You'll see the transmission shift late and hard because it sees no vacuum. (And to the modulator, the lack of vacuum would make the transmission think that the engine is at WOT)

 

[jdknech]

I stand corrected.. must be the lack of sleep getting to me.. sorry for the wrong info..

 

[cucvrus]

Sorry to sound like a know it all. But the TH400 on the CUCV does have an electric down shift. The switch is located on the left side of the trasmission directly below the drives foot. It is the only electric wire that plugs into the transmision. The VCM on the injection pump does NOT control the down shifts of the TH400 in the CUCV. That only controls the up shifts and the timing of the shifts by regulating and sensing and controling the vacuum during acceleration. The orange wire is on a slide switch at the top of throttle pedal and senses when you push the pedal down and then electrically down shifts the transmission to the appropriate gear. Be it first or second. That depends on your speed when you floor it. I hope that helps. And if I am incorrect about minor details in my explanation. I am open for correction. Thank you.

 

[Crash_AF]

Yep, shifting... I meant controls shifting. That's what I get for posting while I'm up with insomnia. LOL

 

[Skinny]

Sorry to sound like a know it all. But the TH400 on the CUCV does have an electric down shift. The switch is located on the left side of the trasmission directly below the drives foot. It is the only electric wire that plugs into the transmision. The VCM on the injection pump does NOT control the down shifts of the TH400 in the CUCV. That only controls the up shifts and the timing of the shifts by regulating and sensing and controling the vacuum during acceleration. The orange wire is on a slide switch at the top of throttle pedal and senses when you push the pedal down and then electrically down shifts the transmission to the appropriate gear. Be it first or second. That depends on your speed when you floor it. I hope that helps. And if I am incorrect about minor details in my explanation. I am open for correction. Thank you.

The kickdown does that, force a downshift at around 3/4 throttle. The vacuum is a signal that goes down to the trans via a hose. It attaches to the modulator which creates modulator pressure in the trans. The governor spins off the trans output shaft and creates governor pressure when vehicle speed increases. When you are driving down the road, the 1-2 shift valve has modulator pressure on one side and governor pressure on the other. It simply battles back and forth till vehicle speed goes up high enough or throttle angle (vacuum signal) goes low enough (high vacuum applied) which pushes the 1-2 shift valve. This then applies the correct brake and creates second gear. Now once the 1-2 shift valve moves, it typically will not downshift until one of the pressures drastically changes. The kickdown signal kind of over rules this if you push the accelerator down far enough.

Simple? You passed day 1 in auto trans class.