I have an '01 durango SLT 4.7. My 4wd hasn't worked in a while and the dealership said the TCCM was shot. so I replaced the TCCM today with a used unit and i now have a green light at the 2WD setting on the switch (i didnt before) and all 3 green lights and the red N lightup at startup for a second. But it still wont shift to any 4wd setting. I put a volt meter on the plug at the transfer case and it reads 0 but when i move the switch it surges for a breif moment then goes back to 0. i expect that is normal right? Any suggestions what it could be or more diagnostics to try?

 

Wow, as long as people keep posting Q's about this problem, I wont have to look too hard to find the fix to mine. Same problem. I Tested at the switch, got 10 or 12 volts at different wires. no changes as I switch it from 2x to 4x. Help Guys, still no lights on my switch telling me its position. can it be as simple as my switch?

 

You should have at least 10 volts at the T-case when you switch. Check the switch as well.

 

It definitely read double digits but I couldn't tell what it read because it was hard to see. But it only showed voltage for a moment while switching then went back to 0. Because the voltage appears at all I assume my switch is fine. I checked it a few months ago before learning that my TCCM was bad.

is there a way to check the motor to make sure it is working?

What other parts are in the system that can be checked?

 

You would have to place 12 volts to the motor leads to see it it engages. If not replace the shift motor.

 

If it does engage, will I be stuck in a 4wd setting? if so, do i reverse the poles to "undo"? Or is there a way to change the setting mechanically instead of electronically i.e. can i turn the selector from under the truck back to 2WD?

 

Well I pulled all information at my disposal and here is my conclusion:

Check to see if you have power at the Mode Sensor. The hot wire (which should be about 5 volts only) is the YL/DB wire. The rest of the 5 leads are the range senors to the TCCM. So in other words, when the shift motor is in the 4low it will ground through one of the leads. This power goes to the TCCM in one of the 5 leads and that information tells the TCCM what mode it is in after the shift. It should be the upper middle lead (with the tab on top).

Now the TCCM has many functions including,

1. A lead coming into it from the PCM telling it the motor is running so ensure it is when testing.
2. A speed sensor output to ensure the vehicle is not moving or moving (or less than 13mph when shifting into low).
3. Range sensor output to see what position the T-case is in.

And many more inputs as well like trans, ignition switch, TPS, overdrive.....ect!

If you loose one of these leads the TCCM will not function or only function in limited sequence. This sequence tells the technician were the issue remains accordingly.

From what I can see the motor is a Bi-Directional motor that is operated by the TCCM by the related information of the mode sensor. Meaning the motor operates in both directions. So technically speaking, yes it should disengage. Now I would assume as you placed the 4X4 selector into 4HI then you would get a single pulse out to the motor leads. Neutral you would get 2 pulses, and 4Low would be 3 pulses. The motor would then be fully extended and the Mode sensor would read accordingly that it fully made each shift. If the shift didn't complete I would sugest a Service 4 Wheel drive light would illuminate.

As I look back at what you have posted, I would concur the that the pulse was infact sent to the Shift Motor but the Shift Motor did not respond causing the failure. I would replace the Shift Motor/Mode Sensor.

If you are uncomfortable about possibly being "stuck" in 4X4 then remove the shift motor assembly and test it on the bench. But I think the motor in your case is shot.

 

Thank you for taking soo much time in researching this issue. I really appreciate it. I am quickly getting to the same conclusion. Do the motors often go bad? i am wondering if replacing it with a used one is wise. Also, is there a "procedure" for removing it or do i just unplug and unbolt?

Thanks again for your help. i hope this will help others too.

 

They do go out because of lack of use and for some reason they can loose connection from corrosion or lack of maintenance.

To replace the motor you need to remove the front drive shaft just at the front of T-case. Remove the Yoke off the T-case. Then remove the Shift Motor.....According to the Service Manual.

Is it worth trying a used one? Depends on you? I don't know if I would if I already replaced the TCCM and I am getting power to the T-case Shift Motor. Kinda seems like I would tend to go directly to the Shift Motor.

Also replace the fluid with ATF+4 transmission fluid. I like Valvoline ATF+4 Fully Synthetic as my favorite at this point. Should need about 1 1/2 quarts.


BTW<---- Your welcome


SHIFT MOTOR
DESCRIPTION
The shift motor (Fig. 78) consists of a permanent
magnet D.C. motor with gear reduction to convert a
high speed-low torque device into a low speed-high
torque device. The output of the device is coupled to
a shaft which internally moves the mode and range
forks that change the transfer case operating ranges.
The motor is rated at 25 amps maximum at 72° F
with 10 volts at the motor leads.
OPERATION
The transfer case shift motor responds to the
Transfer Case Control Module (TCCM) commands to
move the transfer case shift sector bi-directionally, as
required, to obtain the transfer case operating mode
indicated by the instrument panel mounted selector
switch.
REMOVAL
(1) Raise the vehicle on a suitable hoist.
(2) Remove the front propeller shaft. (Refer to 3 -
DIFFERENTIAL & DRIVELINE/PROPELLER
SHAFT/PROPELLER SHAFT - REMOVAL)
(3) Disengage the wiring connectors from the shift
motor and mode sensor.
(4) Remove the front output shaft companion
flange from the transfer case.
(5) Remove the bolts (Fig. 79) holding the shift
motor and mode sensor assembly onto the transfer
case.
(6) Separate the shift motor and mode sensor
assembly from the transfer case.
Fig. 78 Shift Motor - Shown Inverted
1 - TRANSFER CASE SHIFT MOTOR
Fig. 79 Remove the Shift Motor and Mode Sensor
Assembly Bolts
1 - TRANSFER CASE
2 - SHIFT MOTOR AND MODE SENSOR ASSEMBLY
3 - BOLT
AN TRANSFER CASE - NV233 21 - 565
SELECTOR SWITCH (Continued)
INSTALLATION
(1) Verify that the shift sector o-ring is clean and
properly positioned over the shift sector and against
the transfer case.
(2) Position the shift motor and mode sensor
assembly onto the transfer case.
(3) Install the bolts (Fig. 80) to hold the assembly
onto the transfer case. Tighten the bolts to 16-24
N·m (12-18 ft.lbs.).
CAUTION: If the original shift motor and mode sensor
assembly bolts are reused, be sure to use
MoparT Lock & Seal or Loctite™ 242 to replenish
the lock patch material originally found on the bolts
(4) Engage the wiring connectors to the shift motor
and mode sensor.
(5) Install the transfer case front output shaft
companion flange onto the transfer case. Tighten the
flange nut to 122-176 N·m (90-130 ft.lbs.).
(6) Install the front propeller shaft. (Refer to 3 -
DIFFERENTIAL & DRIVELINE/PROPELLER
SHAFT/PROPELLER SHAFT - INSTALLATION)
(7) Refill the transfer case as necessary.
(8) Lower vehicle and verify transfer case operation.

 

What manual are you getting this info from? i would love to see the figures to verify i am checking the right thing. it was a 2 lead black plug that was plugged into a small cylinder the size of a redbull can +/- on the back side of the TC. i plan to jack it up this weekend at my Dad's and have a second set of hands to check the voltage, etc. maybe i just need to clean up the contacts (finger crossed).

Thanks again for your help. We are getting forcasts for our first dose of wintery mix.