NEED HELP : U.S. GEAR Dual Range Over/Underdrive - Parts / Sources

[tigger4x]

Present situation : 1979 J20 w/Cummins T18 Dana20 with divorced Over/Under

Right now the truck tops out at 55mph so I'm assuming it is in the Off or Underdrive setting. I did not find the switch on the stick and after crawling underneath I found that the wiring harness is not hooked up to anything. After downloading the US Gear PDF I found out what the Control Module looks like and will go back and take another look to see if/where it is.

I tried searching forums and googled like a madman, but haven't found a source for any replacement parts. I'd imagine the selector switch would be something that could be cross referenced, but haven't found one yet much less the Control Module. Can anyone point me in the right direction?

[fulsizjeep]

Moved this to Modified FSJ Tech for obvious reasons.

[Stuka]

I have no experience with that unit. But, I don't foresee the electronics being that complex. Its most likely just a set of relays with possibly a circuit to determine what mode its currently in.

If the control module is bad, it could be something as simple as a cracked solder joint, which is very easy to fix. But could also be something more involved. I can probably help some with the electronics side if you need help figuring it out.

[tigger4x]

Moved this to Modified FSJ Tech for obvious reasons.

Thanks Flint

[tigger4x]

I have no experience with that unit. But, I don't foresee the electronics being that complex. Its most likely just a set of relays with possibly a circuit to determine what mode its currently in.

If the control module is bad, it could be something as simple as a cracked solder joint, which is very easy to fix. But could also be something more involved. I can probably help some with the electronics side if you need help figuring it out.

Another Jeeper shared a link with me from a diesel forum that talks about the electronics and such. I'll get it and link it here. If you would give it a peek and let me know what you think. US Gear stopped support for these a good while back so I'm scrambling on this on, drowning mostly. I'll also look over the truck more to see if I can find the control module and anything else related to it.

[tigger4x]

I have no experience with that unit. But, I don't foresee the electronics being that complex. Its most likely just a set of relays with possibly a circuit to determine what mode its currently in.

....

I can probably help some with the electronics side if you need help figuring it out.

I finally broke away and found that link! Hopefully there are some useful gems in there. I can't tell you how much this will mean. My DD is supposed to go to the kiddo before school starts and this will end up being my new DD.


https://www.oilburners.net/threads/us-g ... nfo.65234/

[Stuka]

Ok, this seems really simple.

The version with the external controller (like yours from the sound of it) combined a switch with a timer. The timer engages the switch for ~2 seconds.

Inside the range box, is an electric shift motor. It has two terminals. One for each direction, grounding is done through the case. There is also a stopper to prevent any sort of damage if it happens to be shifted in the same direction multiple times.

As a quick fix, so that you can drive it, all you need to do is apply 12V to one of the sides for around 2 seconds to shift it. Each terminal shifts in a different direction. So you may have to try both to get it into the gear that you want. A battery with some wires should do the trick. Ground the battery to the case when doing so.

As a more permanent fix, assuming your controller may be bad. You could setup two momentary switches to enable a relay for each shift direction, and just know you need to hold the switch in for about two seconds in order for it to shift.

EDIT: Oh, and there are two terminals on the back of the case, these are for the indicator lights to say what gear it is in.

[tgreese]

Double throw - center off - momentary switches do exist. Check the Digikey or Mouser catalogs online.

[tigger4x]

As is the story of my life I can not find the control module anywhere. There is only about 2-3' of wiring harness under the truck inside of a generic wiring loom wrapped around the cross member the unit is mounted to.

[tigger4x]

Double throw - center off - momentary switches do exist. Check the Digikey or Mouser catalogs online.

I imagine one of these would be a simpler version than the two momentary switches that Stuka mentioned. And not having the control module that I need to remember to hold the switch momentarily.

It would be nice to have indicator lights like it's supposed to. My guess is there are other sources out there like the online catalogs you mentioned. I'm rudimentary at best when it comes to this stuff so it ought to be quite entertaining.

[Stuka]

Double throw - center off - momentary switches do exist. Check the Digikey or Mouser catalogs online.

I imagine one of these would be a simpler version than the two momentary switches that Stuka mentioned. And not having the control module that I need to remember to hold the switch momentarily.

It would be nice to have indicator lights like it's supposed to. My guess is there are other sources out there like the online catalogs you mentioned. I'm rudimentary at best when it comes to this stuff so it ought to be quite entertaining.

Wiring would be nearly identical, you just wire it to the pole on each side of the double throw. Two switches just popped into my head. But a double throw, oriented vertically, would make it easy to think about up shifting or downshifting.

[tigger4x]

Wiring would be nearly identical, you just wire it to the pole on each side of the double throw. Two switches just popped into my head. But a double throw, oriented vertically, would make it easy to think about up shifting or downshifting.

Im probably not remembering the information correct, but is it possible that it would only need to be a single momentary switch seeing that once you downshift it automatically disengages the OD? Or would it be better to have the double throw so I can manually take it from OD to regular 4th gear?