Front Drive wont engage but Rear will!?

[firepop607]

I have a 99 explorer w/ 4405 auto torque t/c. When i turn switch to 4x4 high or low t/c will engage, but will not drive front. I have been through some of the GEN Mod. and no sensors jumping out at me. I have got only 2 ideas left. I have heard and read here about acuator motor out of sync, and shift fork broke. I know electro magnet works, cause will engage 4 low to rear axle, and change gear ratio. PLEASE help! If ya'll have anything else i should check let me know. I am able to get into anything just short of a break out box. "don't know anyone w/ one unfortunatley." Thanx!! if ya want to send e-mail i'm at firepop637@yahoo.com Thanx again

 

[my pos mounty]

Before you start going through all things computer controlled and electronic..lets eliminate the mechanical. Put your truck up on a lift or jackstands, so you can turn all the wheels by hand (with it in 4wd). Now grab the front driveshaft and give it a spin. Do the front wheels move with the driveshaft? Did the rears move when you did this?

 

[firepop607]

Had the truck on lift. Did not try that yet. I have already gone through electronics. Buddy has a code trouble shooter. electronics say there is power to actuator. Down to maybe actuator not fully engaging or shift fork broken. Have not had time to get back on lift. If I engage 4 low and spin front shaft front wheels do turn I know, but what is the determination if not turning rear shaft. Shiftfork? Do you know of the actuator not being timed or jumping position? have not taken it apart"off t-case" to inspect it.

 

[gijoecam]

A broken shift fork would be presenting a whole different set of problems... It's not that. The shift motor is not used in the 4auto-4high shift, so we can rule that out.

But I'm still confused.... Which wheels aren't turning? The fronts or the rears? Assuming it's the fronts, just because the computer says it's sending power to the transfer case clutch coil doesn't necessarily mean it's actually reaching the transfer case. There could be a mechanical issue (thinking broken chain) or an electronic issue (thinking open wire in the circuit, bad clutch coil, etc.). I'd start by checking for power at the t-case with the engine idling in drive and the switch set to 4high. Use a multimeter with good sharp tips on it to probe the brown wire near where it enters the transfer case and see if you're getting power down there. I suspect it's not....

 

[firepop607]

Thank's for all your help. When I shift T-Case in 4 low or high With vehicle on rack; rear axle is all that turn. If I shift to 4 low same Prob. Only rear axle turns. I can hear Engagement of something in t-case. Will get a gear reduction to rear axle, but same problem."rear axle only drives" I can understand broken chain. it would fall in line w/ symptoms, and according to schematic it is feaseable. Just looking for anything else to check b-4 having to take truck out of commission. This is my daily driver and can't afford to have out of commission for more than a day. Thank you again, and if you have any other suggestion's it is greatly appreciated.

 

[gijoecam]

Again, bear with the questions... Is the front driveshaft also being driven when in 4low/4auto? (I don't mean just turning, I mean actually being driven and you can't stop it from turning)

 

[firepop607]

No does not turn on it's own when in 4 low or 4 high. Does not engage front drive in auto mode either.

 

[Vargas]

gijoecam is right on the money - "There could be a mechanical issue (thinking broken chain) or an electronic issue (thinking open wire in the circuit, bad clutch coil, etc.)."

I'd add that if failure was quiet, it is one of the electrical issues. The mechanical parts that would have to fail to cause these symptoms would have been noisy as they wore out, or let go with a loud bang. Since you didn't say anything about bad noises, I'd focus on the electrical issues. You might want to try manually energizing the clutch coil (research the "brown wire mod"). If you can make it engage that way, then you know it is on the control side. If not, then the clutch is the problem.

 

[firepop607]

Thank you for your help. As soon as I can get time to put it back on the rack I will try it. As far as the loud bang theary. I bought the truck from my Ass. Chief on fire dept.He owened the truck for 5 years and never engaged the 4 wheel drive. He honestly did not know if it worked or not. I get it and check engine light ABS light on, and Tach.not working. Got dummy lights takin care of. easy fix's Need to find another instrument cluster with a working tach. and fix transfer case then can work on little prob's.Door hinges, lock acuator,and door handle. LIST NEVER ENDS!!! LOL thanks again for your help.