I have a weird issue that I've had the entire time owning this truck that has been particularly hard to solve because the truck thinks nothing is wrong.
Symptoms: no engine lights or codes, when I push a shift button I can hear the transfer case shifting, the LED for what I selected turns on, and when I put it on jack stands 4lo and 4hi move the front wheels too, however when I am in snow or otherwise need 4x4, 4lo and 4hi seem to just be 2wd, although it feels like I'm getting the gear reduction from 4lo, so based on this gear reduction and auto 4wd working, I think my front axle actuator is working, and the transfer case is shifting, as far as I can tell it's just the clutch pack to send power to the front driveshaft isn't doing its job for 4hi and 4lo.
Auto 4wd does seem to be working perfectly and is the only one that actually gives me 4x4.
Everything is smooth, no weird sounds when driving, nothing that would indicate something is wrong or not working except for the fact that I've got no power to the front wheels when in 4hi/4lo.
One thing that could be related (but the more I research, the more I don't think it is) I bought my truck a year ago and after driving it home discovered it had pump rubbed a hole with a previous owner, and the fluid was totally empty. I put Jbweld on the hole, filled it back up, and luckily it seems to be fine, there are no weird sounds, bearings seem fine. There was definitely a bit of what I think was clutch material in the couple drops of fluid that came out when I discovered it but not an amount that seemed concerning, I think it was just settled and concentrated out of the fluid as it escaped over time.
I have a spare 246 (the newer model with the different encoder motor though so I can't direct swap it) to harvest a good rear case without the hole/any parts that look like they need replacing, and a pump rub fix kit that will be going in, but I'm hoping to push that job until warmer weather.
I've been reading into how the tcase works, and some threads from people who had similar issues, and there doesn't seem to be any smoking gun or obvious solution out there but these seem to be the two most likely cases:
1. Apparently the encoder motors have a brake of sorts to stay locked in position once they move to 2wd/4hi/4lo, and if it fails the encoder motor will still be able to shift, but in the case of 4hi and 4lo there is enough pressure from the clutch fork compressing the clutch pack to force the encoder motor to rotate back to where the clutch pack isn't engaged enough, and in 4hi and 4lo apparently the tcm doesn't check again to make sure the position remains where it left it. This would make sense since auto 4wd it constantly modulates so wouldn't have a chance to back off without it being noticed.
2. The clutch discs were worn down enough that the "default" position of the encoder motor for 4hi and 4lo isn't far enough to actually compress the clutch pack to engage fully, so it can drag enough to work on stands but not on the ground. This would also explain auto 4wd working because it doesn't have a set position, it just keeps increasing the force on the clutch pack until it sees the front wheels spinning the same speed as the rear.
I don't think the encoder reported position is the issue because auto 4wd works, and it seems to shift fine between all of the other options including engaging the lower gearing of 4lo.
I'm wondering if the above 2 explanations actually make sense in terms of how everything functions since I couldn't find documentation on if there is actually a brake in the encoder motor, or how 4hi and 4lo positions are set. Also looking for any help diagnosing or suggestions on ways to narrow the issue down. I'd like to avoid firing the parts cannon, and I'm tempted to go pull the encoder motor and take a look inside of it but thought I'd ask here before lying down in the snow.
Thank you much
Symptoms: no engine lights or codes, when I push a shift button I can hear the transfer case shifting, the LED for what I selected turns on, and when I put it on jack stands 4lo and 4hi move the front wheels too, however when I am in snow or otherwise need 4x4, 4lo and 4hi seem to just be 2wd, although it feels like I'm getting the gear reduction from 4lo, so based on this gear reduction and auto 4wd working, I think my front axle actuator is working, and the transfer case is shifting, as far as I can tell it's just the clutch pack to send power to the front driveshaft isn't doing its job for 4hi and 4lo.
Auto 4wd does seem to be working perfectly and is the only one that actually gives me 4x4.
Everything is smooth, no weird sounds when driving, nothing that would indicate something is wrong or not working except for the fact that I've got no power to the front wheels when in 4hi/4lo.
One thing that could be related (but the more I research, the more I don't think it is) I bought my truck a year ago and after driving it home discovered it had pump rubbed a hole with a previous owner, and the fluid was totally empty. I put Jbweld on the hole, filled it back up, and luckily it seems to be fine, there are no weird sounds, bearings seem fine. There was definitely a bit of what I think was clutch material in the couple drops of fluid that came out when I discovered it but not an amount that seemed concerning, I think it was just settled and concentrated out of the fluid as it escaped over time.
I have a spare 246 (the newer model with the different encoder motor though so I can't direct swap it) to harvest a good rear case without the hole/any parts that look like they need replacing, and a pump rub fix kit that will be going in, but I'm hoping to push that job until warmer weather.
I've been reading into how the tcase works, and some threads from people who had similar issues, and there doesn't seem to be any smoking gun or obvious solution out there but these seem to be the two most likely cases:
1. Apparently the encoder motors have a brake of sorts to stay locked in position once they move to 2wd/4hi/4lo, and if it fails the encoder motor will still be able to shift, but in the case of 4hi and 4lo there is enough pressure from the clutch fork compressing the clutch pack to force the encoder motor to rotate back to where the clutch pack isn't engaged enough, and in 4hi and 4lo apparently the tcm doesn't check again to make sure the position remains where it left it. This would make sense since auto 4wd it constantly modulates so wouldn't have a chance to back off without it being noticed.
2. The clutch discs were worn down enough that the "default" position of the encoder motor for 4hi and 4lo isn't far enough to actually compress the clutch pack to engage fully, so it can drag enough to work on stands but not on the ground. This would also explain auto 4wd working because it doesn't have a set position, it just keeps increasing the force on the clutch pack until it sees the front wheels spinning the same speed as the rear.
I don't think the encoder reported position is the issue because auto 4wd works, and it seems to shift fine between all of the other options including engaging the lower gearing of 4lo.
I'm wondering if the above 2 explanations actually make sense in terms of how everything functions since I couldn't find documentation on if there is actually a brake in the encoder motor, or how 4hi and 4lo positions are set. Also looking for any help diagnosing or suggestions on ways to narrow the issue down. I'd like to avoid firing the parts cannon, and I'm tempted to go pull the encoder motor and take a look inside of it but thought I'd ask here before lying down in the snow.
Thank you much
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