2002 Explorer - 4X4 does not work

[Dre]

I've got a client that bought a used 4x4 module from me but even with this new, replacement module, transfer case in his truck does not work.

Here's the short version - he bought the truck with 4x4 not working already, took it to reputable electrician who went through the entire 4X4 and transmission wiring including plugs to make sure power and ground are all where they're suppose to be, checked all fuses and sensors. After that he came to a conclusion that the 4x4 module is dead. After installing a replacement module the situation did not change and 4X4 is well, still dead. Electrician says that there are five live wires going to the module and two ground wires - all five have 12V, ground is OK, fuses are good.
Computer hooked up to the OBD port can't find the 4X4CM like it's not there. Is it another dead module?
Is it something else?

Instrument cluster has been replaced at one point - part numbers did not match the original but everything on the cluster works... could that be the problem? could there be wires that go through the cluster that are mismatched?

I'm at a loss here - I though it would be as simple as replacing the module.

Help!

 

[Dre]

no suggestions? did anyone deal with this? I know people have replaced modules with success - not this time though... I still have to get this thing going before the first snow.

thanks,

 

[imp]

no suggestions? did anyone deal with this? I know people have replaced modules with success - not this time though... I still have to get this thing going before the first snow.

thanks,

The 4x4 shift drive motor receives power from either of two relays located underhood. The motor is driven only to engage and disengage 4X4 LOW.

All 4X4 functions involve power to an electronic clutch within the transfer case. A good bet would be the clutch is faulty, either burned out coil, or mechanically jammed in disengaged position. I would start by using an ohmmeter to check the clutch's coil. The connection to the clutch is via the brown wiring entering the rear of the transfer case, above the drive motor. imp

 

[Dre]

We have not checked the transfer case as of yet, we did check all the power coming into the transfer case and the module... everything is there, power and ground. Let me run some more tests.

thanks!

 

[Dre]

OK... I've got both of the modules - anyone know how I go about checking them?