On-the-fly 4X4 not engaging but neutral shifting works?

UnclMik · #1 02-24-2005, 10:44 AM

I have a 98 F150 and while driving in slippery conditions I reach down to shift from 2WD to 4WD HI, the light does not come on and it doesn't seem to engage. If I stop, put the truck in neutral and shift from 2WD to 4WD HI or LO, the light comes on and it engages.

I just bought the truck last year, and this is my first truck with 4WD.

Can someone help me out with what to look for or fix, before I dreadfully take it to a dealer to diagnose.

Thank You,

P.S. Whether it has anything to do with it or not, my lower ball joints were junk and I had them replaced with grease fittings and had an alignment a couple of weeks ago, and coincidence or not seems to be about the same time that I noticed the on-the-fly 4WD stopped working.

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UnclMik · #2 02-25-2005, 09:25 AM

Since my last posting, now I can not get my 4WD to engage at all, HI or LO, on-the-fly or in neutral.

JMC · #3 02-25-2005, 10:57 AM

Glad to hear that.it is working again. There is a diagnostic procedure to follow if it ever happens again. Just post it up and we can walk you through it.

JMC

UnclMik · #4 02-25-2005, 02:13 PM

It's NOT working at all now. I just spoke too soon, when I said that it worked in 4WD LO, now it doesn't engage in HI or LO, as well. What are the diagnostics that you are speaking of?

Thanks
Mike

UnclMik · #5 02-25-2005, 02:21 PM

I was just checking out your picture gallery and I like the way you have the fog lights behind your grille. I have a 98F150 with the same grille. What light kit do you have back there and do you have to make any special modifications to get them mounted back there?

Thanks,
Mike

JMC · #6 02-25-2005, 02:44 PM

Ok the first thing to check is the T-case. Jack up the front end and support it so it doesn't fall on you. With the key on engine running in park engage 4x4 Hi. Then check to see if you can turn the front drive shaft. If you cannot then then try spinning one of the front tires. The other one should not turn. If they both turn then the front axle is not engaging. Now if the front Drive shaft does turn then then the T-case is not engaging. BTW do you have electric or manual shift on the fly?

JMC

EDIT: spelling

UnclMik · #7 02-25-2005, 04:28 PM

floor shift

JMC · #8 02-25-2005, 04:52 PM

Good, that eliminates the shift motor as a possibility.

JMC

sernabe · #9 02-25-2005, 06:38 PM

I had a similiar problem with my 98 f150 5.4 4x4. It turned out to be a bad vacuum line located by the battery. I assume after a few years of off roading (hunting), battery acid curroded the hard plastic. The dealer had the vacuum lines for 120 buck or something like that. However, i purchased some rubber tubing and replaced the damaged area. 10000 miles later still working like a champ. hope this helps

UnclMik · #10 02-28-2005, 09:48 AM

thanks!