Scavenger1

Hey all! I just joined this forum after buying my first Jeep. It's a 1990 stock XJ w/ auto tranny. Bought it from a private seller. I neglected upon test drive to initiate the 4 wheel drive to see if it works. I know, I know, don't judge. My question is, how do I do a pavement test to check if 4 wheel drive functions properly? I need to do this without taking her offroad. I've searched the interwebs and gotten some conflicting/incomplete information on how to do this properly. Mostly, I want to avoid busting something major. Thanks! Happy to be a part of this amazing forum and call myself a Jeep owner!

studmuffin

Put it in 4lo and slam the gas if it takes off like a bat out of hell on all 4's your 4x4 is working fine all joking aside if your on pavement the truck will start to move without giving it gas and if you turn you can feel it grip but doing this on pavement is not recommended but it's fine for peace of mind if you absolutely have to.

MonacaYankee

Put the jeep in 4low. Obvious difference when your jeep lurches with throttle taps or rpm compared to speed.

Scavenger1

Right on. I will find a straightaway and give this a shot tomorrow. Jeep needs to be in neutral before I put her into 4low. Is this correct? I know this is a newbie question, but then, I AM a newbie. Thanks for your help!

MonacaYankee

Yeah put the transmission in N when shifting into and out of 4low.

cruiser54

Not necessarily guys.....

What if he has a Jeep with the NP231 transfer case and front axle disconnect? The disconnect could be inop for a host of reasons and he wouldn't REALLY be in 4wd. He'd feel the gearing difference in 4L but that's it.

First is the way to shift it and after that is how to test it once it's been shifted.

Here's how the factory suggests you shift the transfer case and I've been doing this since these things were new and I worked at the dealership. Quoted from the owner's manual. The suggestions in CAPS are mine.

"To engage, shift the transfer case lever from 2H to 4H while the vehicle is moving at any legal speed". I LET OFF THE GAS, THROW THE LEVER, TAP THE GAS AND LET OFF.

4L position: " To engage, slow the vehicle to 2-3 MPH , shift the transmission to Neutral, then shift the transfer lever to the right and pull firmly rearward to 4L".

TO SHIFT OUT OF 4L, SHIFT THE TRANSMISSION INTO NEUTRAL WITH THE VEHICLE STOPPED, SHIFT THE TRANSFER CASE LEVER TO 2H, THEN THE TRANS TO D IF YOU HAVE AN AUTOMATIC, OR INTO FIRST GEAR WITH A MANUAL, AND CONTINUE ON.

Revised 11/20/2014



So, get it into 4H per the instructions above in a big parking lot.

Then, make a slow sweeping turn and you should feel the Jeep bucking and the steering wheel jerking. If so, your 4wd works. Per the instructions, drive in a straight line and shift into 2wd.

1976gmc20

When test driving our jeep I found a big gravel parking lot in an industrial area of town.


Put it in the various 4wd selections and turned until I felt the "bucking" - of course there isn't much effect in the "full time" selection.


Low range will be obvious: much higher engine revs and jeep will shift out of first gear at really slow speed (5mph?).

DJKnightmare

4 jack stands, all wheels moving? Yes ... 4wd

thatXJguy

Haha, I like that idea.

Scavenger1

Successful test! Cruiser 54, thanks for the detailed advice. I chickened out on trying it the way you suggested only because the transfer switch shifting is very sticky, and I did not want to break something if I couldn't get the gears to switch quickly enough. I put her in neutral and shifted straight to 4L. It caught and started to move. After that a small moment of panic when the shifter got stuck in 4L. Took me 3 or 4 minutes of messing with it to get it back into 2WD. Thanks everyone for the help!