Hello all!
My 1998 V8 5.6l F150 4 wheel drive will not engage. I move the switch and hear a and electronic click like it is engaging but no go. It was working fine and after sitting in the driveway it stopped, in other words no grinding or trama to it. When I put it in low 4, the transmissions shifts into low but no 4 wheel drive. Where do I start with this one?
Thanks in advance.

 

You probably have a cracked ruber vacum hose that goes to the front diff. Your Transfer case sounds like its engaging low range and 4x4 but the front axle isnt. I would start there. Some others on here will probably have some good ideas on how to track down the leak

 

I did replace the starter recently. Is there a vacume hose by the starter I could have puctured or removed?

 

Im not sure where they route the vacume lines but it would be in that general vacinity i would a assume because i heard of a guy haveing his battery leak and the acid dripping ate his vacume lines.... but im not sure exactly where they come from.

 

that sounds like your problem a leaking vaccum hose it happened to me to

 

If it's the same setup as the '02, you have vacuum control connections on the firewall on the right hand side behind the battery. I had to replace two vacuum hose harnesses. One that runs up from the transfer case to the control and one from the control to another set of hoses under the battery. Also had to replace one control unit (i don't know what it's really called).

Parts cost about $145 through the stealership. You could get hoses and run it all piecing it out. I found it easier to replace the whole harness.

It's only a two beer job if you take your time.

GY

If you send me your email address in a PM, I'll take a couple of pics and show you what I had to replace.

 

What's the definitive way to test if the 4x4 functionality is working on these babies? Jack them up at all corners ? Rolling ROad?

I have the same scenario as yours I think but I'm not entirely sure whether 4WD is working or not...

Thanks
Gav.

Expy 5.4L XLT 4x4.

 

i have a 98 f150 and it is doing the exact same thing. if u got yours working would u mind telling me what you did to get urs working if u did get it working

 

I still do not have a solution. I will have to take it tothe dealer and have them go through and diagnose the problem

 

try looking at the ground switch on the transfer case.. I had to change mine looks like a oil pressure switch, I beleive it has one red wire going to it they go bad quite often. they are about 25-35 dollars

 

I will try that...
I just want to verify symptoms, All seems to work, it will switch the transmission into low, 4wd light goes on just no 4wd. I will check to see if i have to wire connected. thanks

 

You can do some verification with a driveway test with the right front off the ground.
place in 4wd. leave in park. You must start the truck to activate the vacuum.

Turn the driveshaft by hand.
Front driveshaft will not turn(engaged). TCase is working.

Turn the r-front tire by hand. if the driveshaft turns then the tcase is not engaging. If the driveshaft does not then the vacuum is not engauging the couple of the r-front to the diff.

Pull the hoses from the vacuum pot on the front axle. Then and have someone start the truck and switch from 2wd to 4wd while you listen and feel for the vacuum to change from one line to the other. If there is vacuum then look for the actuator to move when hooked back up.

A control issue like nobow mentioned might disable any of this from happening. but hopefully it will help from a mechanical view.

 

Vac Sylenoid, you should have two of them one is for enguage and one is for disenguage located behinde battery on fire wall try checking those out...

 

My 99 LD F250 had the same problem. I found out after I sheered a ball joint trying to power my way up a hill in "4 wheel drive". I was in 2, cause I had a dry rotted vacuum line. The hard plastic lines crack on you, as the trucks are now 8 or 9 years old. Take the battery out, remove the battery tray. You will see a black box that attaches to the battery tray with vacuum lines coming out of it. Trace those lines and you will find all of the vacuum hoses you need to look at to fix your problem. After sheering my balljoint, I replace those, as well as all of the front suspension(didn't want it to happen again) and then I had to have my fender, hood and door fixed as the tire pushed the body where it didn't belong.