Non-functional 4WD, No flashing lights, No nothing
I am a new member with a 2002 XLT 4.6L V8 4WD who just joined because of the existing member-info pertaining to this topic which contributed to my ability to
just solve my problem! As I sit back with a victory "
cold one", I want to share my experience which may help others & cost
nothing but a little time.
Go to the bottom of this post to bypass the background info & get my particular solution, or else read on...
Background: The weather has been unseasonably warm & I am taking advantage of doing anything outside where I would otherwise freeze my a*ss off. I usually test 4WD function well before the snow falls. If I haven't been off-roading during non-winter, I still at least check 4WD at the beginning of each season. Well, I checked last week & I got nothing...
- no lights
- no click
- no 4WD High, no 4WD Low
Uh oh, better solve this before the snows flys & solve it without just throwing money at it. I discovered this forum & read
everything on all threads pertaining to this subject.
The only thing different from the last time I checked 4WD was that I
did finally replace the
original battery this past June 2011. I read with interest about other members' original 4WD CM frying out at times when this task is performed.
Ok. What else could cause this? I read about poor grounding or broken wiring at the transfer case & about harness connections coming loose. There's also the possibility of the transfer case motor crapping out.
Troubleshooting Process:
So I decided on a logical process of elimination.
- With the vehicle running, nothing happens when I press the 4WD Selector Switch, but when I turn the ignition key to start the vehicle, I see the 4WD Low & the then the 4WD High instrumentation lights briefly light up as expected (the 4WD Low light exhibits more "light" time than the 4WD High light. At first I thought I wasn't seeing the 4WD High light at all). Ok, so what's keeping the transfer case motor from doing its thing? What can I first inspect without being invasive?
- Although I use my X under all types of conditions, it's pretty clean, undamaged & unabused...but there's still the possibility of the exposed wiring connected to the transfer case getting corroded or disconnected. Under the X I went. I removed the heatshield for inspection. Everything looks fine. I wiggled the wires (especially the grounding wire). All were clean, undamaged & seemed solidly anchored). I started the X & tested 4WD. Nothing. Ok, time to look at harness connections to modules & switches.
- The Control Module is easier to get to than the selector switch. Just drop open the glovebox (I don't want to remove the front console bezel if I don't have to). I wanted to write down the 4WD CM part number info anyway to see if it is original, to compare with what other members have stated was in their 2002, and to provide with my VIN incase a replacement is necessary. 2 harnesses connect to the bottom of the Module. The harness closest to me felt like it was not completely seated. I pulled it down slightly then firmly seated it back into position. I did the same to the rear harness (which seemed more firmly bedded than the first). I then restarted the vehicle & selected 4WD. IT WORKS exactly as it's supposed too!
I confirmed the function of both ranges. All lights, all sounds, all mechanicals are doing what they are supposed to do. If reseating the CM harnesses did nothing, I was next going to check the harnesses for the selector switch. Then do continuity checks of these key components, then most likely purchase a new CM.
Bottom-line: With a set of jackstands & a floorjack,
anybody can at least save on the cost of labor & a potential rip-off of being charged for uneccessary parts by performing the same tasks as I did. You will at least be able to zero-in on what is
not wrong with your 4WD system (and the hundreds or more dollars a dealer or service provider may try sticking you with).
Potential Solution:
So, long-story short, before freaking out & throwing lots of money hoping to fix the problem, open up the glove box access to the 4WD Control Module and reseat its connections. You too may be as happy as I was to see the 4WD High & Low dash lights light up and the click of the transfer case function like they are supposed too!
Here's to hoping your solution is as straight-forward & satisfying as mine was. Once again, a lot of the info I used to formulate my process was provided by members who took the time to post their experience to the forum. I thank them & reciprocate by doing them same.
