Hi, I am new to the forums. I purchased a '97 F150 SC Lariat 4x4 with electronic shift on the fly about a month or so ago. We have had a couple of small snowfalls since then and when I would put it in 4wd it would sometimes make a couple of loud pops when I started to accelerate. Now, a couple of weeks later, we had quite a bit of snow yesterday and my 4wd was acting up. Sometimes it would engage and sometimes it would not. The 4x4 light on the dash lights up so I think the transfer case is engaging, but the front axle doesn't engage. Also sometimes it sounds like it is trying to engage but can't fully do it...it makes kind of a whining/grinding noise in the front end and as soon as I flip the switch to 2wd it stops making the noise. Today I have tried to use the 4wd a couple of times and it didn't work the first time, but when I got into my truck about 4 hours later I tried it and it worked. I have also tried 4 Lo and it seams to switch to lower gearing but the front wheels still are not pulling. Could this possibly be a vacuum problem like mentioned in some of the other posts?

 

I would venture to guess you may have a vaccum problem, transfer case, or front diff problem. Start with the basics... I would check vaccum and then check fluid in the front diff and tansfer case. Good luck

 

Thanks for the quick reply! I checked the vacuum lines last night with a vacuum tester. It was fine at the solenoids and at the front dif. The transfer case is engaging ok...I could spin the front drive shaft freely when the dash switch was in 2H and it would not turn when in 4H so the problem has to be up at the front dif. I had the fluids changed about 2 weeks ago and haven't noticed any leaks so itshould be good. I just don't understand why it would sometimes work and sometimes not work. And to add to it my gas pedal is sticking now.

 

Just tested the vacuum again when 4x4 wasn't working and both solenoids have a vacuum at the same time. What does this mean, is one of the solenoids causing the problem?

 

my 2003 was doing the same thing check the drive shaft to the front axel first see if it is spining in 4wd, (back up to a pile of snow and spin the rear wheels if you see the driveshaft spining then the transfercase is working next shift it in to 2wd and look under the truck at the front diff on the passenger side there is a vacume accuator see if it is pulling the shift lever in or out when you switch in to 4wd and 2wd if so then its most likely your shift fork is shot. this is a very simple part to change. but dont go to a dealer they want $950 to change the part out it took me about 3 hrs with hand tools, if you have air tools maybe 1 hr and a half. if you need to know how to change it let me know

 

Well I decided to spray some WD-40 in the solenoid to try and stop it from sticking if that was the problem. We had a huge snowstorm and the 4WD worked perfect the whole time. Idk if that was the problem or not but hopefully it keeps working!

 

MIne did the exact same thing,seems engaged but front wheels not spinning.IM not as mechanically inclined as others nor do i have a garage so im taking it to ford on monday and have them fix it as its got a few days under warrenty left.

 

I don't know if your problem would be the same because you have a slightly older truck but my 2002 and 2004 both did this and its the solenoid on the pass. side.The design of these trucks causes water or melted ice to drop down on solenoid causing the problem.Both times the dealership fixed mine they changed the actuator and solenoid and put a cover over solenoid with no further problems.

 

I may try changing the passenger solenoid then b/c it started acting up again. Must have just been coincidence that it worked after using WD-40 b/c about 3 days later it started doing the same thing again. It has a mind of its own...works when it wants to!