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Getting the "part time" light to work after a disco to non-disco axle swap

xjtrailrider

xjtrailrider

NAXJA Forum User
NAXJA Member
Location
Roanoke VA
Yes I have searched:sure:

I just got around to swapping in a 96 HP D-30 into my 90 and I would like for the part time light to work since I'm not the only one that may drive this Jeep.

There are 3 vacuum hoses at the actuator, one red, one yellow and one white. What do I do with them?
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

Well, you have a three-port switch on the transfer case--supply, engaged, disengaged. Engaged/disengaged runs to the vacuum motor you no longer have. When the transfer case lever is pulled to part-time the t-case switch sends vacuum to the motor which pulls the collar into engagement of the axle--at that time the part-time light port on the vacuum motor sends vacuum up the firewall to the vacuum-to-electric switch, and from that switch the part-time light is activated.

Option 1: block off the disengaged port on the t-case switch and run a vacuum line from the t-case switch engaged port up to the vacuum-to-electric switch on the firewall.

Option 2: purchase the later, 95+ I think, electric t-case switch and run the necessary wires for that.

Option 3: install a small plunger switch similar to the parking brake switch under the console to trigger the part-time light.

That is all I've got.
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

I swapped from disco to non-disco a couple years ago, but couldn't for the life of me remember if the PT light worked......

Just for you, I went out and checked the heep-- the PT light is on in 4HI and 4LO (231 case), but I don't remember what I did with each vacuum line:(

It's parked in the middle of a 3' show bank right now (and it's dark out) but I'll pull her out and see what I did in the A.M.-- provided no one else posts up before then...
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

Joe, do you have "colors" for the vacuum line(s) that I need to tie together? Also, couldnt I just jumper the lines at the end of the vacuum harness (white and yellow) to get the light to work?

I think the green line(sorry called it red in my post) has to be plugged since its always pulling vacuum, correct?

I used the old actuator to try to see how the vacuum ran around through it and it seems the white and yellow get connected when the actuator connects the two axle halves.

So I think I can jumper those 2, just thinkin!
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

Shorty said:
I swapped from disco to non-disco a couple years ago, but couldn't for the life of me remember if the PT light worked......

Just for you, I went out and checked the heep-- the PT light is on in 4HI and 4LO (231 case), but I don't remember what I did with each vacuum line:(

It's parked in the middle of a 3' show bank right now (and it's dark out) but I'll pull her out and see what I did in the A.M.-- provided no one else posts up before then...
Click to expand...

No problem Shorty, I'm working in the garage thankfully and most of our snow melted today.
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

Shorty said:
I swapped from disco to non-disco a couple years ago, but couldn't for the life of me remember if the PT light worked......

Just for you, I went out and checked the heep-- the PT light is on in 4HI and 4LO (231 case), but I don't remember what I did with each vacuum line:(

It's parked in the middle of a 3' show bank right now (and it's dark out) but I'll pull her out and see what I did in the A.M.-- provided no one else posts up before then...
Click to expand...

Wuss--just kidding, all the snow on the ground has melted here but I'm not crawling under ANYTHING outside.
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

xjtrailrider said:
Joe, do you have "colors" for the vacuum line(s) that I need to tie together? Also, couldnt I just jumper the lines at the end of the vacuum harness (white and yellow) to get the light to work?

I think the green line(sorry called it red in my post) has to be plugged since its always pulling vacuum, correct?

I used the old actuator to try to see how the vacuum ran around through it and it seems the white and yellow get connected when the actuator connects the two axle halves.

So I think I can jumper those 2, just thinkin!
Click to expand...

Yeah, start the engine, put the lever in 4Hi or 4Lo and identify the line up by where the vacuum motor was located, then just hook it up with the short line that runs up to the switch on the firewall--that should do it.

Don't forget to plug off the other (disengage) vacuum line or you will a vacuum leak when in 2wd.
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

joe_peters said:
Yeah, start the engine, put the lever in 4Hi or 4Lo and identify the line up by where the vacuum motor was located, then just hook it up with the short line that runs up to the switch on the firewall--that should do it.

Don't forget to plug off the other (disengage) vacuum line or you will a vacuum leak when in 2wd.
Click to expand...

Thank You! I'll get right on this!
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

xjtrailrider said:
I think the green line(sorry called it red in my post) has to be plugged since its always pulling vacuum, correct?

So I think I can jumper those 2, just thinkin!
Click to expand...

this sounds very familiar-- IIRC, a vacuum cap on one and a 4" piece of hose looped between the other two is about all I did....... 'course I found it on here with a search, so I guess you just suck at searching......:D

P.S. most of our snow melted too (40* today), but when you've got a Jeep, you look for the snow pile to park on-- especially when YOU plowed it into your own parking spot:looser:
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

Yep I suck at searching on here or maybe our search function is just too precise. I pulled up about 30 threads about the subject but no one described in detail how to remedy the issue. I even think i started a thread about this a year or so ago and could not find that either, LOL!

Hey my trail rig is parked on a snow pile in the driveway as well, Its a Jeep thing!
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

Well crap! that didn't work:doh:

When the actuator is hooked up(I pulled it off the old axle just to try it), the light works. But when i jumper the white to yellow, it does not work! By what I can tell, that is all that is happening to divert the vacuum to the switch under the reservoir.

Vacuum is being pulled from the white hose through the second port on the actuator when the actuator is in the 4wd position. So white should hook to yellow to get the light to work....right!

Green is the 2wd position and should be capped...I think, damn:gag:

Anyway, Shorty take a look at yours when you get a chance and tell me what you did to make it work. Maybe the hose that i am using is collapsing.
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

should be three hard lines looping from the actuator up, along the fire wall. The top line and bottom line get connected and the center line gets capped off.

pics to follow if they turn out clearer than mud...
 
Last edited:
Re: Getting the "part time" light to work after a disco to non-disco axle swap

pictures looked like poop-- why'd ya have to wait 'til it's dark out, again?

copied from another thread:
It's really not that hard. You should have a vacum line connector near the passenger firewall that joins the lines coming up from the vacum motor to the switch down on the old transfer case, etc.
The red line is manifold vacum. Plug it if you want to wedge the vacum motor.
On the other hand, I believe that if you connect it to the yellow line, it should "pull" the vacum motor into the 4wd position and hold it there. If you connect it to the green line, it will move it to the 2wd position. The third line (I forget the color) on the vacum motor goes to the "part time" light switch. When the motor is in the 4wd position, vacum is passed to this port and goes to the switch. You will need to either leave it connected to the switch, or plug the port or line.

vacuumbypass.jpg

the looped lines are the two that are farthest apart and the middle line is capped
 
Last edited:
Re: Getting the "part time" light to work after a disco to non-disco axle swap

THATS exactly how I did mine and it doesn't work:smsoap:

If i hook the actuator up it does work.

I'll try some better hose tomorrow
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

I can't believe the hose is collapsing any more than mine (notice it's about 99% folded over)but I guess it can't hurt to find something better suited to make the loop.
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

Shorty said:
I can't believe the hose is collapsing any more than mine (notice it's about 99% folded over)but I guess it can't hurt to find something better suited to make the loop.
Click to expand...

I'm using some clear 2-cycle fuel line from AA and its looped about like yours, I also used some small zip ties to help seal it even tighter. I will try some rubber vacuum line tomorrow and see what happens.
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

Make a piggy-tail out of it--loop it around a couple of times, tie it off with a ziptie or two to hold the loops, that should keep it from kinking so much.
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

Still not working. Even with better hose. I'll try other things tomorrow.
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

xjtrailrider said:
Still not working. Even with better hose. I'll try other things tomorrow.
Click to expand...

Nevermind:wierd:

And thanks for all of the help Joe and Shorty, its working now. I took the Jeep out for a drive today and on a straight stretch of road i decided to pull the lever into 4hi and give the new front DS a feel, when I did, the stupid light came on:eyes:

I tried it several times, works like a charm now, even just sitting in the driveway, so i really don't know what the issue was with it. Maybe the switch is getting ready to go.
 
Re: Getting the "part time" light to work after a disco to non-disco axle swap

good to hear-- I was really tryin' to figure out how it would work with the actuator, but not with the jumper!
 
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