Hey guys, my 4wd won't engage


Transfer case shifts fine, front axle not engaging though and little light doesn't come on.

Any ideas what to try first?

Thanks.

 

Check for detached, cracked or broken vacuum lines going to the 4wd actuator on the top pass side of the front axle.

 

i agree with infidel,
there are 2 vacuum lines under your truck one red, one black
make sure there in place..
hopefully thats all thats wrong

 

It is either a vacuum leak, or a bad switch. Go get a vacuum tester from the auto parts store, it'll cost like 15 bucks. Pull off the vaccum lines up at the axle, at one of the rubber boots. You should be getting around 25 in/Hg. If I remember right, the black one is for engaging, and the red is for disengaging. If you are not getting vaccum, go up to the transfer case, take the rubber boot off one of the flexible lines, and test it there. If you are still getting nothing, it is probably the switch. Water can work up there through worn lines and freeze up the switch.

If you don't get it working, there is a way to bypass the switch. You need to go on the driver side of the transfer case. There is a black square block with 4 vacuum lines going into it. Pull out the grey (I am pretty sure, if not it is the green line) and connect it with the black line going into the block. Now you should be locked in 4WD. If you are, get a new switch, 20 bucks. I had to get a new jumper harness (plastic lines that connect to vacuum block), because the old block had formed to the old switch and leaked with the new one. It cost 20 bucks, but it is cheap to know that yo'll always have 4WD. Good Luck!

 

on my 1997, down at the vacuum pump/ power steering pump, i have a vacuum line the has a large black boot that has a 90 degree bend on it. once, when i was working under the hood on something- i disconnected it for easy access(easily pops on and off). i forgot to hook it up when i was done it prohibited me from engaging into 4wd. i assume this provides all vacuum for the truck-maybe you'll want to try to operate your different heater outlet selections (floor, bi-level, defrost,etc) to see if they work. it could be your culprit.

 

It's your vacuum

 

I Had basically the same thing happen to me but it was after the dealer changed the tranny in my truck they forgot to zip tie the vacuum lines and a couple days later the truck magically didn't have 4wd the lines got covered in snow and fell down got hooked by the driveshaft and ripped right out, got new lines the next day, zip tied em in and havn't had a problem since.

 

Hmmm....

Haven't had time to investigate yet as I have been away.

But it appears something is freexing up .

I went to the Ohio beef expo in Columbus this weekend, saturday was real warm. 65 -70 degrees?


Just out of curiosity I pulled it into 4wd, light immdiately came on, 4wd was working.

Get back home this morning and it's 10 degrees F snowing and blowing like crazy. 4wd not working.

 

Difinitely a frozen switch. That is EXACTLY what mine did, we heated it up in the middle of a storm, got the 4WD locked in, went outside and plowed, and couldn't get it to come out of 4WD. Only costs like 25 bucks at the dealer.

 

Okay, thanks guys.

I'll have to go get one I guess.


I was crawling around under it for a while today. didn't se any vacuum lines off. But none of them have any clamps or anything on there to keep them tight.

 

If you want to fix the problem forever, go to this site and click on Dodge for the cable kit to replace the vacuum lines and vacuum motor: http://www.4x4posi-lok.com/ When you shift this in, it is in, not in limboland!

 

I was going to install the posi lock when my 4wd had a little blirp this winter. The reason I didn't is because the person I talked to on the phone said that the last 1/4 of engagement is crucial, and he went on to make it sound like it was hard to get it fully engaged. I decided to stay with the vacuum system, because it can ALWAYS be engaged, whether by the switch, or by manually connecting vacuum or even taking the CAD cover off and physically sliding the collar over the shafts.