Help with 4WD indicator light

BuckeyeJeep

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Nov 19, 2021
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Lancaster, Ohio
Morning guys, happy thanksgiving
Got a question concerning my 4wd indicator light……. 95 YJ, 4 liter 5 speed
My 4wd works, both high and low, but the indicator light on my gauge panel doesn’t come on.
I’ve changed bulbs and that’s not the issue
Tried to read about the vacuum and 2 piece axles etc but wondered if there was a switch like a replaced in an 02 TJ?
Confused and any help or insight is appreciated. Thanks
 
Are you sure your in “4 wheel drive”
The locker on the front axle is vacuum actuated and Meg have a vacuum leak…. If so, you may only be 3-wheel drive. My 89 had all tubes cracked and broken…. I switched to posi-lok.
 
I’m not 100% positive, but when I’m 4 wheel drive on dry pavement the steering wheel kinda jerks back and forth and grabs like it’s supposed to in 4 wheel drive
 
The switch that lights the light is built into the vacuum housing. Could be that your vacuum CAD isn’t engaging, or that your switch is dead.
 
Similar issue, slight twist, looking for wisom. 1992 4.0 Auto Sahara. Yes, 4wd works. Yes, light on dash works (tested by looping small wire on switch lead at front axle). Yes, when the acuator is manually pressed, switch turns on light (tested by zip tying actuator). But, I can't get 4wd light to come on in its normal setup. If there is enough vacuum to move the fork and engage 4wd, shouldn't there be enough pressure to acuate the light switch in the housing? The acuator felt pliable enough to me. Any suggestions? Should I test vacuum pressure? If so, what should it be?
 
It doesn’t take much vacuum to move the fork/collar over. It takes a bit more to press the button on the switch once the fork is moved over, and to hold it there pressing the button. Maybe you have a small vacuum leak that affects things just enough to not be able to push the switch but enough to move the fork to where it needs to be for 4wd to work.
 
Similar issue, slight twist, looking for wisom. 1992 4.0 Auto Sahara. Yes, 4wd works. Yes, light on dash works (tested by looping small wire on switch lead at front axle). Yes, when the acuator is manually pressed, switch turns on light (tested by zip tying actuator). But, I can't get 4wd light to come on in its normal setup. If there is enough vacuum to move the fork and engage 4wd, shouldn't there be enough pressure to acuate the light switch in the housing? The acuator felt pliable enough to me. Any suggestions? Should I test vacuum pressure? If so, what should it be?
Sometimes these types of switches can wear a little and make it not work in normal operation but you're able to push it far enough to make it work by hand. Might be worth inspecting the switch a little closer. Specifically, the little ball on the end that forms the plunger. I've dealt with a similar issue on reverse switches on CJs. I could manually make them work but the shift rail wasn't able to depress them enough due to wear.

600-551-003.jpg
 
It doesn’t take much vacuum to move the fork/collar over. It takes a bit more to press the button on the switch once the fork is moved over, and to hold it there pressing the button. Maybe you have a small vacuum leak that affects things just enough to not be able to push the switch but enough to move the fork to where it needs to be for 4wd to work.
Ok good info, thanks for the quick reply.
 
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Sometimes these types of switches can wear a little and make it not work in normal operation but you're able to push it far enough to make it work by hand. Might be worth inspecting the switch a little closer. Specifically, the little ball on the end that forms the plunger. I've dealt with a similar issue on reverse switches on CJs. I could manually make them work but the shift rail wasn't able to depress them enough due to wear.

View attachment 122132
Ok good tip, thanks.
 
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Ok, now I have to come clean and admit, embarrassingly, I was actually NOT getting 4wd. So sorry to have wasted folks time, duh. The low gearing threw me off and I am new to this. So now my issue is that there does not seem to be any vacuum (sucking?) when I put it in 4wd, yes engine running, and I put my finger over the 2 vacuum hoses at the front. I then went all the way back to the 4 pronged vacuum thingy on the transmission bell housing. Can't feel anything. I'm guessing that is the part that needs replacing? Should I at least feel something? Much obliged if anyone stuck around this far.
 
Ok, now I have to come clean and admit, embarrassingly, I was actually NOT getting 4wd. So sorry to have wasted folks time, duh. The low gearing threw me off and I am new to this. So now my issue is that there does not seem to be any vacuum (sucking?) when I put it in 4wd, yes engine running, and I put my finger over the 2 vacuum hoses at the front. I then went all the way back to the 4 pronged vacuum thingy on the transmission bell housing. Can't feel anything. I'm guessing that is the part that needs replacing? Should I at least feel something? Much obliged if anyone stuck around this far.
This makes more sense. I wanted to suggest verifying the 4x4 was working yesterday.

When you pull the 4 hole vacuum hose off of the vacuum switch (the 4 prong piece), do you feel suction from any of the 4 holes in the hose when you have the engine running? You should. If not, then you might not be hooked up to the intake manifold vacuum nipple properly.

If you do have a problem with the switch, you can buy a new Mopar switch for about $70 which is better quality/reliability than parts store parts.
 
You da man. No, when I have it in 4wd hi, engine running in neutral, i can't feel a thing on the 4 pronged vacuum switch back at the tramsmission housing. You mentioned, is it hooked up to the intake manifold properly? I see there are two small vacuum lines going up to engine bay, one droops down and is capped. The other goes to a T on the intake manifold, all seems to hooked up ok. I disconnected at the first T and I feel suction, same at other T on its way down to 4 pronged vacuum switch. So seems like a new vacuum switch is logical next step?
 
You da man. No, when I have it in 4wd hi, engine running in neutral, i can't feel a thing on the 4 pronged vacuum switch back at the tramsmission housing. You mentioned, is it hooked up to the intake manifold properly? I see there are two small vacuum lines going up to engine bay, one droops down and is capped. The other goes to a T on the intake manifold, all seems to hooked up ok. I disconnected at the first T and I feel suction, same at other T on its way down to 4 pronged vacuum switch. So seems like a new vacuum switch is logical next step?
sounds like you’re good on the intake manifold.

What I’m asking about at the transfer case is if you feel suction on any of the 4 holes on the hose. The piece screwed into the transfer case is the switch, that may or may not be bad but you need to be feeling suction on the hose when engine is running.

You won’t feel anything on the switch because it has to be unplugged to feel anything.

Hose I’m talking about
IMG_2549.jpeg

Switch I’m talking about:
IMG_2551.jpeg
 
If you pull the connector at the t-case you should still feel vacuum at the 4 port plug. You're going to need to chase the vacuum lines and check them.
 
If you pull the connector at the t-case you should still feel vacuum at the 4 port plug. You're going to need to chase the vacuum lines and check them.
I don’t see how that could be once the hose is off and no longer providing vacuum on any of the 4 ports?