Hello fellows, first post here but not new to the site. I have been looking on this awesome forum for a while and have gotten great information.
I had an issue with my 2004 FX4 SCREW with the 4X4. I had noticed when it rained mostly and I tried to switch to 4X4 the light will come on for just a moment then out. After that I could turn the switch and no lights would come on. Eventually, some other day it would work again.
By reading this site I decided to change the solenoid yesterday. I replaced it with the new model, turn on the 4X4, not raining, and it did the same. Only that after I turned off the truck and back on, with the 4X4 switch off, it turned on on 4X4 low and just can't get it out of there.
I read that the issues can be on the TC motor. If I check for curent on those cables do they have constant power or is it just momentary when you turn the switch?
Also, somebody else reported a corroted cable on the distribution box under the hood. I imagine this is the one sending power to the tc motor. Can somebody tell me where that box is and how to identify that cable?

Thanks in advance!

HM.

 

Update : problem fixed. Thanks to all the valuable information in this forum I was able to fix the problem. For anybody having problems with 4x4 engaging, light turning on and immediately off; take off the two relays under the hood and clean the contacts, wd40 and scrape them with a flat screw driver. It now goes in and out immediately....I am glad I did not change the TC switch.....

 

good to know! I am now having this exact issue......

 

I think you're going to find that you have a temprary fix at best. In order for corrosion to start, the plating on the terminals must have been compromised. Once that happens, there's little you can do to prevent it from returning. Sure, you did clean it up and now have a temporary good electrical path, but it will corrode again. I'd recommend replacing the offending components.

Little Tip: Apply corrosion resistant grease or Dielectric grease to the terminals next time to prevent the corrosion from starting.

 

Actually the build up wasn't rust, it was more like a coat of glue of some type. The connections at the fuse box looked clean. The tip of using dielectric grase sounds great, thanks!