Hi everyone,

Just picked up a pretty clean 1998 F150 XLT Supercab 4x4.

I tested the 4-hi and low before buying, with no problems. Now it won't go into 4x4. Sometimes it does, but when you need 4x4 it doesn't seem to click in.

I hear, and feel the linkage clicking in, but the dash light doesn't come on. The light works, and when the 4x4 does engage, the light clicks right on, and everything is fine.

Is there a switch or solenoid that goes bad??
My truck has the shifter on the floor. I thought it was all mechanical?

Thanks for helping the new guy .

~Jim

 

Jim, there are a few different things that could be going wrong as I went through this about 3 months ago.\

1st thing I would do is start at the firewall, there are two solenoids behind the battery on the passenger side that activate and deactivate the 4 wheel. Make sure by having someone in the cab with truck running that they click when you engage, if this works then work your way down to the front end. If these don't click then get out your book and find the fuse that operates that.(probably not your problem since it works sometimes)

2nd remove the plastic cover from the front diff and again have someone put it in 4 wheel drive while you are laying under the truck. I put mine on stands and had all four tires off ground. You will see a diaphragm that has a small arm that goes in and out, make sure that is working. If not try to move it manually to make sure it is not frozen. If you can move it but it doesn't move when shifting to 4 wheel then you probably have a hole in the small vacuum lines that activate that. It can be hard to find but take your time and you will find it.

My guess is the diaprhagm since it is intermittant.

These are all easy fixes once you find the problem.

Good luck

 

Jim: I have a '98 4x4 with the manual shifter. Mine did the exact thing yours is doing. On the front side of the transfer case, where the linkage goes into the case, you will see a plug with a wire harness leading to it. The switch screws into the case. Just unscrew this plug, it is a switch that tells the truck it is in 4-wheel. It turns on the 4x4 dash light and activates the vacuum motor on the front axle to engage the front axles. The part number is on the switch. It cost me about $26 and was easy to replace. Also, lube the vacuum motor actuator shaft and you should be good to go.

Good Luck!

Dan

 

Thanks to both of you.

Dan, it appears to be the switch you mention on the front of the t-case. I pulled, cleaned, and lubed and it grabs 4x4 every time. I still ordered a replacement switch ($24) to be safe.

Hopefully this is all it was.

BiG THANKS again .
This site is a great source of info with some smart, helpful members!

 

Everything is working great. Here is the switch in case others need the info.

 

I'm looking at the same model and year truck as described (98 F150 XLT). When attempting to engage 4H I needed two arms and a CONSIDERABLE AMOUNT of force to engage 4WD. It did, and the light came on. I can't believe how stiff the range stick was. Anyone else have abest guess on this? This is my first truck with 4WD, so I'm a bit green about them.

Steve

 

Get under the truck and lube all the transfer case linkage while someone inside shifts the truck in and out of 4x4.

I find it shifts into 4x4 easiest on level ground too.

 

Seems that all is well now after a liberal dosing of lube...thanks...

Steve

 

My '98 did the same thing. I did find one of the solenoids on the firewall bad. Removed, tested and it absolutely was bad. I replaced it, then it would only actually go into 4 wheel drive when the temperature was below about 35 degrees. And, the lo-range light would never come on. Finally, removed the switch on front of transfer case, checked it, , , even put it in the freezer to cool down and then check the continuity and it proved to be bad. Changed and all works as it should now. My switch, unfortunately, cost $52.00, but it's fixed now. I also lubricated the mechanism on the differential motor. Also, the lo-range light now comes on.