4WD won't engage

Bullet3600 · #1 (**permalink**) 07-20-2003, 08:00 PM

I've read some of the past postings and tried a few things but to no avail. I have 4LO after it kinda grinds in with no light on the dash coming on for P/T but still have no high range. I've checked for vacuum leaks at the axle and followed all and no leaks, removed vacuum connector from the right front axle and cleaned it out refitted it and still same problem. any ideas would be extremly helpful, Thanks..........Bullet :-?

edited by: Bullet3600, Mar 06, 2003 - 10:06 PM[addsig]

Bounty__Hunter · #2 (**permalink**) 07-20-2003, 08:00 PM

The transfer case is likely shifting into 4hi and 4lo fine, the problem is the pass. side front axleshaft is not locking.

Troubleshoot by:

Jeep Running, in park or neutral with e-brake on
Pull the 2-line vacuum connector from the front axle
Have a friend shift from 2wd to 4wd and back
Vacuum should be strong in one line for 4wd and other line for 2wd

What you found:

Weak vacuum in one line, then other = vacuum leak in system
No Vacuum = Bad switch at transfer case, or no vacuum from manifold
Vacuum in one line, but not other = Vacuum leak or bad switch at transfer case

[addsig]

Bullet3600 · #3 (**permalink**) 07-20-2003, 08:00 PM

Hunter, I put the jeep up today and with it running and in 4wd I had no vacuum to the vacuum modulator on the front axle(Which I replaced last week :-x ) so I took off the vacuum switch at the transfer case and found the ball valve at the bottom very hard to move and sticking. So tomorrow's agenda after taking 3 out of 4 of my kids for haircuts is getting a new switch then hopefully this beast will work again..........Bullet[addsig]

Bounty__Hunter · #4 (**permalink**) 07-20-2003, 08:00 PM

Cool. Let us know if that fixes the problem. I've never had that switch out of the transfer case, never had a problem with one. I'll have to take one out some time and check it out.[addsig]

Bullet3600 · #5 (**permalink**) 07-20-2003, 08:00 PM

The part is simple, all it has is a ball valve on the bottom. I ordered it al it will be here on Monday..............Bullet[addsig]

Bullet3600 · #6 (**permalink**) 07-20-2003, 08:00 PM

Aaaarrrrrrrrggggggghhhhhh, I just replaced the vacuum switch on the transfer case case and still no vacuum. Could someone let me know where the manifold vacuum is or where to look for it. If that doesn't work I guess i'm just gonna have to be happy with 2wd :-( ................Bullet[addsig]

XJNick · #7 (**permalink**) 07-20-2003, 08:00 PM

A Red vacuum line is the vacuum source line at the T-Case switch. This line connects into a "Y" splitter that sends Manifold vacuum to the T-case switch and to the Vacuum reservoir. The "Y" is right around the where the EGR Canister is (at the firewall where the A/C lines go through.) Check for Vacuum there. The "Y" 's source line plugs into the Manifold just behind the throttle body and next to the Air temperature sensor.

Good Luck

-Nick

edited by: XJNick, Mar 02, 2003 - 09:57 PM[addsig]

Bullet3600 · #8 (**permalink**) 07-20-2003, 08:00 PM

Thanks Nick, I will check it out in the morning. I appreciate the quick reply..........Bullet[addsig]

Bullet3600 · #9 (**permalink**) 07-20-2003, 08:00 PM

I checked for vacuum in the red lines and at the Y's and I have plenty of vacuum there but still no no 4wd :-x :-x :-x , with everything that i've replaced it it comes down to the transfer case itself I quit.............Bullet[addsig]

XJNick · #10 (**permalink**) 07-20-2003, 08:00 PM

So you have vacuum in the red line at the Vacuum Switch end? Must be the vacuum switch isn't being engaged by the shift lever linkage inside the transfer case. Maybe adjusting the shift lever linkage would help. Could also be why the 4LO grinds when engageing

-Nick

edited by: XJNick, Mar 03, 2003 - 05:58 PM[addsig]

Bullet3600 · #11 (**permalink**) 07-20-2003, 08:00 PM

How difficult is it to adjust this? Do I I have to drop the trans case? I am desperate to have this work and tired of blowing money to fix it. I appreciate your help Nick.........Bullet[addsig]

XJNick · #12 (**permalink**) 07-20-2003, 08:00 PM

Adjusting the shift linkage is easy. You don't have to drop the Transfer Case. Get under the Jeep and look around where the shifter comes through to the underside (by driver's side of transmission). There is one rod that comes off the shifter which is pinched to another rod by a bolt. That rod goes into the transfer case. The Haynes manual says to put the shift rod into 4LO then adjusting it. I had to play with it some to get it adjusted. You know if you've adjusted it too much if the lever won't return fully to the 2HI position. It's easier than it sounds.

-Nick[addsig]

MudDawg · #13 (**permalink**) 07-20-2003, 08:00 PM

Where are you checking for vacuum??? check at the connectors where the plastic lines hook to the metal lines at the firewall...i had a problem once where rust got in the steel lines going down to the axle...no vacuum at the axle...vacuum at the firewall...

BUT... if the problem is in the front end...you would still have high and low range to the rear end...just the front end wouldnt pull....does the shifter feel mushy and sloppy?? if so maybe it is the adjustment or loose shift lever nut on the linkage at the t-fer case..

Dawg[addsig]

Bullet3600 · #14 (**permalink**) 07-20-2003, 08:00 PM

I was checking for vacuum at the Y connectors next to the fire wall. Just like you said I had vacuum at the firewall but not at the vacuum actuator on the front axle. What i'm going to try is buy some vacuum tubing and bypass the metal lines altogether, maybe with a little luck I may actually get somewhere with this beast..............Bullet[addsig]

Bullet3600 · #15 (**permalink**) 07-20-2003, 08:00 PM

Here's the latest. After adjusting the linkage and smashing my finger so bad the emergency had to burn holes in my finger nail to relieve pressure . I have manifold vacuum in the red line going from the manifold to the Y and then to the vacuum switch at the trans case. No vacuum coming out of the switch to the yellow, green or white lines which go to the vacuum actuator on the front axle. Since the vacuum switch is new is it possible it may be defective in some way or the problem is internal with the trans case. I have rebuilt almost everything on the engine and axles and have never come across something so confusing in my life as this 4wd system.............Bullet[addsig]