Vaccum Motor Problems??

[jeepyj]

I have a 95 jeep yj. Recently i had some problems with Vaccum motor on axle,engages 4x4. I replaced motor,but still wont engage? My light on the dash is showing it's engaged,But Its not.. What could the Problem be? I noticed the collar wouldn't move fully to left when it was apart.. Maybe Its bound up?
If its bound up it shouldnt be lighted up on dash right? Showing its engaged... Hmmmm? Confused??

 

[Bounty__Hunter]

With a '95, the shift collar is usually engaged if the 4wd light is on. The 4wd light switch is on the disconnect and is activated by the shift collar moving into the engaged position.

The shift collar will not slide into place unless the splines on both axleshafts are lined up, this may take rotation of one shaft or the other and is usually immediate if you're driving.

If you need the shift collar to be engaged for 4wd in a pinch, slide the collar into position over both axleshafts and install the disconnect upside down. This will hold the collar in the locked position.

Welcome to the Z.

 

[jeepyj]

So is it possible for the axle on drivers side to move? Not allowing shift collar over enough to engage..But light still lighting up on dash?

 

[Bounty__Hunter]

I don't know how it's possible for your light to come on without the shift collar moving and engaging both axleshafts.

I would find out why the shift collar is binding, try to rotate the pass. side inner axleshaft by hand while moving the shift collar over both shafts. Also shift from 2wd to 4wd while the disconnect is removed from the axle but hooked up to vacuum, to ensure it's working properly.

 

[SteelHeadz]

If you've verified that the front axle is not engaged and the 4X4 light is still on, the switch is either stuck or shorted close. If you disconnect the switch connector and the lamp shuts off then the problem on the lamp issue is in the switch, if it doesn't turn off, you need to look in the wiring for a short to ground.

 

[87SixInlineYJ]

I had someone with a Jeep Wrangler today give me some advice and I wasent sure about it until now after reading this. He explained to me that he believed that his 4L and 4H were not working as well. He was like we spent the entire day trying to get it to engage. He explained that he was about to just say 4*$#@ it until he did something that made complete sense.

He was like look, whatever you do, when you engage 4 wheel drive, do it in the dirt, or on grounds that are far from completely even like a road. He was like, the jeep must have some sort of sensor or something because while in the street, the jeep would not move, it just sat there. Although, when he tried it in the dirt, it worked like a charm!

Just a little story, who knows .....

 

[jeepyj]

So the only time a jeep will let you engage the 4x4 is when its ready to play!!! LOL.... Ill try that. Thanks for the story. I think they sometimes do have a mind of their own...Ha Ha!!

 

[roosterman1655]

As I understand it, the YJ is flawed and the only way to eliminate the vacuum motor problem is to replace it with a manual cable system. They are expensive, about $215.00. I found one on another site for $199.00 and another site that showed how to build your own. I will just save up for the big money one since you get what you pay for. Mine started acting up two winters ago. At first a tighter seal on the lines seemed to work, this lasted about three months. Now it will engage but it constantly slips out. It might be that the shift fork is worn or there is not enough vacuum, but once I remove the cover I will lose fluid and need another gasket. So, rather than spend a lot of money chasing a cure you should just buy the solution.

 

[buckshot500]

Maybe the vacuum lines got switched somehow.

Here's a schematic, if you want to check.

 

[Bounty__Hunter]

That diagram is fine for early YJ's before the moved the 4wd indicator switch to the disconnect housing on the axle like the 95. Everything before the axle is the same.

 

[lqdtrance]

So, is this diagram good for a 93 & 94 YJ 2.5?

 

[Bounty__Hunter]

I don't think so, I think the switchover was around '91 but not sure.

It's close for every YJ, the '91+ just didn't have the white vacuum line on the axle but an electrical connection instead, from the axle mounted 4wd light switch back to the computer.