I'm having problems with my 4wd. In 2h the 4wd light comes on and the front driveshaft engages however I ripped around on some slick mud and I don't think the front tires moved. In what seems to be 4h according to the shifter, the fwd light shuts off and the front driveshaft is not engaged. In neutral, the front driveshaft engages again with no 4wd light. However in 4L the 4wd seems to work great but with no light still. 🤯

Please someone who knows more share some thoughts. I would punch my dash if it wasn't a gen 2 and in pieces already. The only thing that seems to makes sense is it's rebuild time for the transfer case.

 

4WD engages via a cad (central axle disconnect) on the front axle. It works off of vacuum. When it engages 4WD a switch in the cad turns the light on. I would first verify you have good vacuum at the cad for both 2 and 4WD and the cad is moving.

 

First you've gotta see what vacuum is doing at the CAD.

I can never remember which is which (a web search would get you there) but pull the two lines and apply vacuum and see which engages and which disengages. Then, those should receive vacuum respectively in 2wd and 4wd.

If so, you might see if that vacuum drops dramatically at higher throttle, indicating a significant vac leak, although usually the CAD needs not only a drop in vacuum but full reversal from red to black or vice versa to slide the collar the other way.

The other part of the system is the vac switch in the t-case which is a very simple ball plunger vac switch. And the connector on top of the switch commonly degrades and causes lots of whacky symptoms. The entire harness from engine bay to vac switch is available for ~$40 in OEM Mopar and is easy to replace.

 

I suspect the lines on the actuator on the front axle are hooked up backwards.

 

I considered that, too, but aren't they in a molded rubber connector making reversal nearly impossible? Of course it's possible it degraded and someone cut them and attached with a short length of rubber vac hose.

 

It's still possible to hook 'em up backward. But, it just doesn't look right that way. Given the behavior of his, I think that is the first place I would be lookin'.

 

[QUOTE=Moparite;3565326]4WD engages via a cad (central axle disconnect) on the front axle. It works off of vacuum. When it engages 4WD a switch in the cad turns the light on. I would first verify you have good vacuum at the cad for both 2 and 4WD and the cad is moving.

 

[QUOTE=HeyYou;3565334]I suspect the lines on the actuator on the front axle are hooked up backwards.[That could definitely make sense I'll check for that thank you.]

 

On my '95, tubes point down on the actuator, and red is the outer one.

 

[QUOTE=HeikIlm;3565352]On my '95, tubes point down on the actuator, and red is the outer one.[yeah looks like mine are pointing the right way then. maybe flipped elsewhere?]