3rd Gen 4x4 not engaging, lights function. Looking for ideas.

[JonathanExp]

2002 explorer V8, 4WD (4WD auto, 4WD high, 4WD low), 250k on the engine and transfer case.

About a month ago I went on an off road camping trip. While driving on the highway my ABS light came on. A few days later I found myself stuck in some sand with only the rear wheels engaged fueling my suspicion that the ABS light was likely deactivating my 4WD. Once home I pulled a C1237 (rear wheel speed sensor) code and replaced a cracked rear differential speed sensor. After replacing the sensor I took the truck off road to verify the 4WD operation and found that my front wheels would not turn when I lose traction such as trying to go up a very steep gravel/dirt hill.

I ran a quick code scan and pulled a B1676 (battery voltage out of range) which I cleared and has not come back after a couple of starts.

My 4WD drive lights have functioned normally before and after the sensor replacement and I can hear the 4WD low engaging.

I put the truck up on stands and started it cold. All four wheels began turning roughly the same speed when I put it in drive (4WD auto). After a few minutes of warming up, when I put the truck in drive again the front wheels would engage after a few seconds of the rear wheels turning and the front wheels were probably turning a little slower than the rear. After waiting a few more minutes, when I put the truck in drive again the front wheels would not turn on their own until I stepped on the gas then the front wheels would start spinning. I tried this over two occasions and it was consistent for 4WD auto/high/low.

I ran a more comprehensive code scan and found a C1095 (ABS pump and motor). When I put the truck in drive on the stands the ABS light did flash for a second but went away. I guessing it was this code. With the truck on the stands and in drive, I hit the brakes and it feels like the ABS is kicking in.

I also have a seat belt pretensioner fault and an oil pressure switch fault that popped up which I assume neither have to do with the 4WD.

I would really appreciate any ideas or suggestions of things to try.

Jonathan

 

[Fix4Dirt]

2002 explorer V8, 4WD (4WD auto, 4WD high, 4WD low), 250k on the engine and transfer case.

About a month ago I went on an off road camping trip. While driving on the highway my ABS light came on. A few days later I found myself stuck in some sand with only the rear wheels engaged fueling my suspicion that the ABS light was likely deactivating my 4WD. Once home I pulled a C1237 (rear wheel speed sensor) code and replaced a cracked rear differential speed sensor. After replacing the sensor I took the truck off road to verify the 4WD operation and found that my front wheels would not turn when I lose traction such as trying to go up a very steep gravel/dirt hill.

I ran a quick code scan and pulled a B1676 (battery voltage out of range) which I cleared and has not come back after a couple of starts.

My 4WD drive lights have functioned normally before and after the sensor replacement and I can hear the 4WD low engaging.

I put the truck up on stands and started it cold. All four wheels began turning roughly the same speed when I put it in drive (4WD auto). After a few minutes of warming up, when I put the truck in drive again the front wheels would engage after a few seconds of the rear wheels turning and the front wheels were probably turning a little slower than the rear. After waiting a few more minutes, when I put the truck in drive again the front wheels would not turn on their own until I stepped on the gas then the front wheels would start spinning. I tried this over two occasions and it was consistent for 4WD auto/high/low.

I ran a more comprehensive code scan and found a C1095 (ABS pump and motor). When I put the truck in drive on the stands the ABS light did flash for a second but went away. I guessing it was this code. With the truck on the stands and in drive, I hit the brakes and it feels like the ABS is kicking in.

I also have a seat belt pretensioner fault and an oil pressure switch fault that popped up which I assume neither have to do with the 4WD.

I would really appreciate any ideas or suggestions of things to try.

Jonathan

im not too sure, but this sounds like it could be the clutch in the 4405? iirc your 3g has a live axle front, so it shoyld be spinning st the same rate if slip is detected. can you look at the wheel speeds as read by the rig in forscan obdlink etc? wheel speed sensor can trugger that abs code too. hmmm do you have rsc? just curious wonder if the brake could be hokding the fronts if it thinks theres slippage etc im in doubt but just curious, anyways i wonder about the clutch because its supposed to keep the front and rear rotsting st the same speed. and since it gets worse as it heats up i wonder if its almost like its fading as it hesrs up? can you test so see how much is going through the brown wire? in the 2g it can be accessed under the seat or behind the dash. iirc its maybe 5a? not too sure

 

[JonathanExp]

Thank you for the reply. I do not have stability control. I will try to see if I can read the wheel speed sensors later today. Once the truck is warmed up and in drive I am able to spin the front wheel with my foot so I am doubtful the brake is holding it.

What should I be looking for when testing the brown wire?

 

[Fix4Dirt]

Thank you for the reply. I do not have stability control. I will try to see if I can read the wheel speed sensors later today. Once the truck is warmed up and in drive I am able to spin the front wheel with my foot so I am doubtful the brake is holding it.

What should I be looking for when testing the brown wire?

if there is power going theough it or not usually iirc it was 5a that sends the power through the ckutch to make it send poeer to the front. but not 100% sure so lets see what others say

 

[JonathanExp]

I was able to measure the voltage of the brown wire. In park 1.1 volts in A4WD and 2.5 volts in 4WD high. Both jump to 12.6 volts when I step on the gas.

Thoughts?

 

[Fix4Dirt]

I was able to measure the voltage of the brown wire. In park 1.1 volts in A4WD and 2.5 volts in 4WD high. Both jump to 12.6 volts when I step on the gas.

Thoughts?

the 1.1 in park and the jump to 12 seems ok (i think)!considering that its 4a and its then sending the power to the front. the 4h is the one that confused me a bit since it should be consistently sending 12v to the front i woukd asume since its a 50/50 split it isnt auto done jts just 50/50. hmmm

 

[JonathanExp]

so, for some reason I was not able to measure the current across the brown wire. I checked I was measuring current correctly by measuring something else but not much out of the wire. when i had it set to milliamps it did bounce around a little when i back off the gas but that is it.

if the TC clutch is toast should i expect any warning lights?

 

[Fix4Dirt]

so, for some reason I was not able to measure the current across the brown wire. I checked I was measuring current correctly by measuring something else but not much out of the wire. when i had it set to milliamps it did bounce around a little when i back off the gas but that is it.

if the TC clutch is toast should i expect any warning lights?

thats really interesting. not too sure, i wonder if its not sending power such as from the gem etc. i dont think a light would cone on if the clutch is toast since it has nk way of knowing. that said jf the tc is starting to go out i heae they bang aroubd