Seeing as it's that time of year again, I thought I might create a quick, dirty, and simple troubleshooting procedure for those having issues. I don't plan to cover all the possible causes, but it's quite easy to narrow it down to a mechanical issue with the transfer case, front axle, or an electrical gremlin. Everyone seems to start with 'My 4wd isn't working! What now?' so here's my quick answer to help you get started troubleshooting.
Background
First, on the 2nd gen Explorers, there are a few different transfer case setups depending on the model and year. I'll try and be as comprehensive as possible, but I'll probably miss a couple.
If you have an all wheel drive V-8-equipped Explorer, you have a Borg-Warner 44-06 transfer case. It uses a viscous coupling between the front and rear driveshafts. It's a relatively simple system, with no switches, knobs, or electronics to fail. I won't get into troubleshooting here because there isn't much to do. In general, either it works, or it doesn't.
The 44-05 transfer cases used behind all the V-6 second-gen Explorers fall into a few groups:
--The 95-96 4-doors have an electronically controlled t-case. They also use a electro-vacuum-actuated center-axle disconnect to lock and unlock the passenger side axle shaft.
--The 97-01 4-doors, and the 95-00 Sports use the same 44-05 transfer case as the 95-96, minus the center-axle disconnect in favor of a live axle.
--The '01-'04 Sport and '01-'04(maybe '05?) Sport Trac uses a 44-05, but it functions much like the 1st-gen's 13-54 (i.e. it uses a lockup collar actuated by the shift motor).
When in doubt as to which group you fall into, use the control knob on your dash as the guide.
I won't get into the precise details of the inner workings of the transfer case here. If you're curious, there's more info at the beginning of the
'Comprehensive Brown Wire Mod Thread'. If you still have detailed questions about the inner workings of the t-case, please start a new thread. Someone more knowledgable than I will be along shortly to serve inquiring minds.
Now, that being said, I want to make one important note perfectly clear:
If you have a 95-01 4-door, or a 95-00 Sport, the transfer case shift motor does not control the transfer case lockup. The transfer case shift motor is solely responsible for range selection and range selection only. If the 4 wheel drive is not working on the afore-mentioned models/years, it's absolutely NOT the fault of the shift motor, and the shift motor does NOT need to be
Also, if your mechanic suggests that you've blown the hubs on your second gen Explorer, laugh uproariously, then run, don't walk, to another mechanic. You do not have locking hubs that can fail like the first-generation Explorers did. The outer CV joints are solidly splined to the front wheel flange/hub assemblies, just like on a front wheel drive car. If your 'hubs' are bad, you'll know it (and it'll have nothing to do with your 4wd system).
Finally, please note that I'm making the assumption that your 4wd light comes on in any of these cases. If the 4wd light is not coming on to start with, please start a new thread and we'll go from there. Each model and year's wiring can vary slightly, so to try and include every combination here would be very difficult.
OK, enough background. Let's get started!
My 4wd light comes on, but it isn't working: Now What?!!?
95-96
Your control knob should say 2wd, 4auto, 4low.
First, we need to narrow it down to a transfer case issue, or a front axle issue.
Step 1) Jack up the front end and place it securely on jack stands.
Step 2) Verify that the front driveshaft turns by hand. When turning the front driveshaft by hand, the front wheels may or may not turn. Do not be alarmed if they don't turn. This is normal for your vehicle.
Step 3) Start the vehicle and let it idle. Place your foot firmly on the
brakes, place the transmission in
NEUTRAL, engage
4low, then place the vehicle back in
park.
DO NOT ENGAGE ANY GEAR!! The lurch as the transmission engages could cause the vehicle to lurch and potentially fall off the jack stands.**If you can turn the front driveshaft, the transfer case is not locking. This could be due to a mechanical issue with the transfer case itself, or an electrical gremlin with the control system. Start a new thread with the results of your checks, and we'll go from there.
**If the front driveshaft does not turn, the transfer case is locking properly and we need to continue searching.
Step 4)
With the front wheels in the air, engine idling in PARK, spin one front wheel. The other wheel should spin the opposite direction. If both wheels spin in opposite directions, then the front axle *should* be properly engaged. Take it for a test drive (after safely lowering it to the ground, of course). If the front wheels do not spin in opposite directions, there is a problem with the front axle. This could be due to a mechanical problem with the diff, or a failure of the center axle disconnect to engage the passenger side axle shaft. Start a new thread with the results of your checks, and we'll go from there.
Troubleshooting the CAD on a 95-96 is a bit more involved than I want to get into here, and the problems can vary widely. This'll get you started.
97-01 4-door and 96-00 Sports
Your control knob should say 4auto, 4high, 4low.
First, we need to narrow it down to a transfer case issue, or a front axle issue.
Step 1) Jack up the front end and place it securely on jack stands.
Step 2) Verify that the front driveshaft turns by hand. When turning the front driveshaft by hand, the front wheels should turn. (If only one turns, don't be alarmed. One wheel sometimes has more resistance in the brakes, bearings, or CV joints. This is normal)
Step 3) Start the vehicle and let it idle in PARK. Engage 4high. DO NOT PUT THE VEHICLE IN GEAR!!! Crawl underneath and see if you can turn the front driveshaft.
**If you can turn the front driveshaft, the transfer case is not locking. This could be due to a mechanical issue with the transfer case itself, or an electrical gremlin with the control system. Start a new thread with the results of your checks, and we'll go from there.
**If the front driveshaft does not turn, the transfer case is locking properly and we need to continue searching.
Step 4) With the front wheels in the air, engine idling in PARK, spin one front wheel. The other wheel should spin the opposite direction. If both wheels spin in opposite directions, then the front axle *should* be properly engaged. Take it for a test drive (after safely lowering it to the ground, of course). If the front wheels do not spin in opposite directions, there is a problem with the front axle. Start a new thread with the results of your checks, and we'll go from there.
'01-'03 Sport and '01-'05 Sport Trac
Your control knob should say 2wd, 4high, 4low
The transfer case in these trucks functions essentially like the 1st-gens' 13-54 t-case. (i.e. it uses a lockup collar engaged by the transfer case shift motor) The troubleshooting procedure is very similar, but you don't need to worry about hubs or center-axle disconnects engaging.
Step 1) Jack up the front end and place it securely on jack stands.
Step 2) Verify that the front driveshaft turns by hand. When turning the front driveshaft by hand, the front wheels should turn. (If only one turns, don't be alarmed. One wheel sometimes has more resistance in the brakes, bearings, or CV joints. This is normal)
Step 3) Start the vehicle and let it idle in PARK. Engage 4high. DO NOT PUT THE VEHICLE IN GEAR!!! Crawl underneath and see if you can turn the front driveshaft.
**If you can turn the front driveshaft, the transfer case is not locking. The shift motor could be falsely reading an incorrect t-case position, or it could be a mechanical issue with the case itself. Start a new thread with the results of your checks, and we'll go from there.
**If the front driveshaft does not turn, the transfer case is locking properly and we need to continue searching.
Step 4) With the front wheels in the air, engine idling in PARK, spin one front wheel. The other wheel should spin the opposite direction. If it does, the system should be properly engaged. Safely lower the vehicle to the ground and take it for a test drive. If the wheels do NOT spin in opposite directions, there is a problem with the front differential or axle. Start a new thread with the results of your checks, and we'll go from there.
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IF YOU HAVE MORE QUESTIONS ABOUT YOUR SPECIFIC VEHICLE'S PROBLEM, PLEASE START A NEW THREAD DESCRIBING YOUR TROUBLE. Please limit the discussion here to details specific to this troubleshooting procedure.
I hope this helps a few people get started!!
Now what did I forget? Tips? Comments? Suggestions? I'm all ears!
-Joe