4x4 Problem

[ColbyHorsman]

Hi, I did some searching around about my four wheel drive not engaging and I think I may understand what the problem is, but could someone confirm this?

My four wheel drive doesn't engage. I switch to 4 high and the light comes on, I switch to 4 low (in neutral and stopped) and I hear the clunk(transmission?) and the light turns on. If I put the truck in and drive it while in 4 high or low the front driveshaft turns but I still get now spinning on the front wheels while stuck.

So now do I jack up one front wheel and try to spin it? Or is that only for first gen explorers?

 

[gmanpaint]

I am assuming you have a 2nd gen V-6 4x4 from the forum your posting in. You have not said otherwise, & your Info on your avatar is missing. The year matters on the front axle for testing the front drive shaft.

Place the truck on 4 stands.... Carefully!!

Place in 4 low/drive. Let it idle and see if all 4 wheels spin. This will tell you if your low range is working.

In 4 high/drive, let it idle and see if the fronts move at all on their own. The rears should be turning faster than the fronts, or the fronts will speed up, slow down in spurts. The 4405 t-case will be sending power to the fronts in 5% increments to match the rears speed.

If that is all good, you might have an ABS problem. Is your ABS light on?

With an open front dif, you should at least get 1 wheel to spin (the 1 not stuck )

 

[ColbyHorsman]

Yes it is, it's a '99 explorer sport, 4x4 V6 SOHC, and yes my ABS light IS on! But has been on since I bought the truck and the 4wd problem just started.

 

[gmanpaint]

The ABS & 4wd system work hand in hand. The GEM sends the signal to the t-case via the ABS system. If the ABS light is on, there is a problem and the 4wd system will not function properly.

You may have a bad rear sensor in the axle housing, or you might have a bad sensor in one of the front hubs.

I had a sensor going out and the 4wd still worked until the sensor completely died in a hub. I had the rear sensor get dirty and it stopped the 4wd from working. I removed it, and cleaned it. That did the trick for it.

Front hub sensor is almost as expensive as getting a new hub with a new sensor included, so I would just get a whole new hub. The rear sensor is less than $30 from the dealer, and takes all of 5 mins tops to replace.

 

[ColbyHorsman]

Makes perfect sense. I think I'll start by removing the rear sensor and giving it sa good cleaning. The previous owner of the truck told me he had replaced the front sensors before he sold me the truck.

 

[ColbyHorsman]

The guy owned the truck before me said he replaced the front wheel speed sensors, so I assumed it was the rear sensor. So I just replaced it, to no avail.

How would I check the wheel speed sensors? I have a meter, should I just check continuity?