1997 TJ TDI swap transmission transfer case questions

[ozark]

I acquired this as a project and have been able to get the engine running, ECU mounted, and exhaust connected. Supposed to have upgraded trans and transfer case. The transfer case is a NP 231J, not sure about the trans. Trying the connect jeep wiring to transfer case but the connections don't match and I have a 4WD light on the dash. I've attached pics of the trans and transfer case.
Thanks for any help U can offer

 

[hear]

that transfer case is vacuum-actuated, what you'd find on some(all?) YJ's. That's what that "4 port manifold" plug is. The plug hiding behind it looks to be the 4WD indicator plug. The foreground is an O2 sensor plug, and I can't tell what's behind it, but it looks to have 2 wires coming out of the plug but only 1 wire in the broken loom.

Calling @machoheadgames for everything you ever wanted to know about transfer cases.

EDIT: the vacuum plug is to handle the front axle disconnects, not to shift the t-case itself. I'm dumb.

 

[ozark]

that transfer case is vacuum-actuated, what you'd find on some(all?) YJ's. That's what that "4 port manifold" plug is. The plug hiding behind it looks to be the 4WD indicator plug. The foreground is an O2 sensor plug, and I can't tell what's behind it, but it looks to have 2 wires coming out of the plug but only 1 wire in the broken loom.

Calling @machoheadgames for everything you ever wanted to know about transfer cases.

It has a manual, cable actuated, transfer case lever. It seems to work. I haven't tried to drive it yet. I think the 2 wire goes to the speedometer . I don't have an 02 sensor. I just have to figure out where to connect the 4WD switch.

Thanks

 

[Gilaguy23]

The only thing that switch does is light up the 4wd light. manually shifting it will put it in 4wd regardless of the vac switch being working or not.

 

[machoheadgames]

I believe that is an early XJ (pre-91) transfer case as I don’t believe any other vehicles had the vacuum switch on the tail housing. The rest including the YJ were all mounted on the front case half. The transfer case is all mechanically actuated, the vacuum switch is for engaging the front axle fork on vehicles with CAD motors on the front axle. Aka YJs, pre-91 XJs, etc.

Your light on the dash would have initially been operated by an electrical switch on the front case half, in the same location where a YJ model transfer case would have had its vacuum switch. I’m going to guess your transfer case doesn’t have that hole in th case half..the XJ cases that had the rear mounted vacuum switch did not have a hole in the front case half. So the only way you would have one is if that transfer case is a hodge podge of mixed up parts. Which is possible.

First thing is to look for the hole for the electrical switch on the front half. If it’s missing, you may not be able to get the light working. If the hole is not there, you’d want to try screwing in an electrical switch in place of the vacuum switch on the tail housing. The switches all use the same threads, but I’m not sure the throw of the button on the switch will be actuated properly by the 4x4 fork which is what actuates the rear mounted switches.

So, look for the hole and if it’s there, mount a switch and wire it up. If not, try a switch in the vacuum spot. If that fails, buy a different transfer case and do whatever you need to do to it to make the input work with your current transmission.