THM400 Kick Down Switch

[48cj2a]

Does anyone know if the THM400 kick down switch that is mounted above the gas pedal was eliminated at any point?

I swapped in a Civy 6.2 into my M1009 CUCV Blazer from a 1987 R2500 Crew. I also swapped the Civy dash and engine harness at the same time to eliminate the 24v starting system, relay, military glow plug controller and to gain the factory cluster gauges.

I finally took it on the first test drive last night and it seems to downshift correctly when mashing pedal and climbing hills so I was curious if it was later integraded into the system with out the need for the separate switch.

[Vin82k3500]

Do you have the detent cable atatchment that goes where the vaccum modulator would go if it was a gas job ?

[Vin82k3500]

Do you have the detent cable atatchment that goes where the vaccum modulator would go if it was a gas job ?

sounds like it does as long as you have that it would seem that it would work fine since most of the th 400 s shifts are controlled my vacuum and gov pressure as i think all diesel th400s have that cable mine did its only the gassers that needed the full throttle switch i believe

[48cj2a]

sounds like it does as long as you have that it would seem that it would work fine since most of the th 400 s shifts are controlled my vacuum and gov pressure as i think all diesel th400s have that cable mine did its only the gassers that needed the full throttle switch i believe

The only cable is the accelerator cable. There is a steel vacuum line coming off the rh side of the tranny and going up to the vacuum unit and the IP switch. The single orange wire coming off the lh side of the tranny switch is the one that I thought was part of the kick down circuit but when reattached everything under the dash there was not a connection to the kick down switch above the gas pedal.

Both the CUCV and the Civy donor had 6.2s and thm400's but I did not know if the wiring was separate and I forgot to snag it off the donor.

[Vin82k3500]

that one was different than the one I had mine had a cable going right where the vacuum line is on yours it was a unit that replaced the modulator and it worked great for the time I used it when i didnt need overdrive

[john8662]

The switch on the injection pump is your kick down switch, there isn't anything on the gas petal itself.

J

[Manimal]

Hey Art!
My '82 had the orange wire and switch on the gas pedal for the kick down. The vacuum switch on the injection pump is for the vacuum modulator on the trans.
Lance

[Robyn]

"most" TH400 trannies use a vacuum modulator and the diesels used a vacuum switch on the RH side of the IP to simulate "throttle oepning" to control the throttle pressure circuit in the tranny.

Some military units actually used a cable setup from the IP down to a mechanical modulator.

I have seen this on the HMMWV but not on the CUCV.

The orange wire on the LH side of the TH400 (single wire) is a 12V power wire that activates a little solenoid on the valvebody to cause the 3-2 forced downshift.

This orange wire connects to a little switch mounted above the throttle pedal.

One can live without this function, but the only way to get a 3-2 downshift would be to manually pull the shift lever.

Missy

[Vin82k3500]

not sure it you see the photo but this is the cable setup my th400 and 6.2 had

[master53yoda]

After doing a total rebuild on the th400 in my 83 motorhome, Missy's description is exactly the way my motorhome is set up, the switch forces a down shift at full acceleration that the modulator or governor won't override. My motorhome has twin turbos and a manually shifted gear-vendors overdrive behind it and I use an additional 2-3 shift control in line with the gear vendors so that it will stay in 2nd over when pulling a hill so that i don't have to move the lever etc when up shifting from 2nd over to 3rd under it is just a single shift point.

I also found that I had to adjust the new modulator a substantial amount to get the shift points to work correctly as the vacuum switch on the side of the IP is an on or off control rather then varying the vacuum as a gas engine does based on throttle position.

[Vin82k3500]

who knows what was in this mongrel of mine

I think its less of a mongrel now with a dodge tranny

good to know since mine is the only one I have been into

[Vin82k3500]

who knows what was in this mongrel of mine

I think its less of a mongrel now with a dodge tranny

good to know since mine is the only one I have been into

mine was converted from a 700 r4 so I was told