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Old May 22nd, 2018, 11:12
WB9YZU WB9YZU is offline
NAXJA Forum User
Join Date: Feb 2004
Location: Madison, WI
Posts: 6,941
Re: Service 4WD System

I've been putzing with it and looking at the FSM. Don't have a code reader for the FDCM, but I am getting voltages at the shift motor connector.

The setup is interesting enough. The shift motor contains a motor, electric clutch, 3 sets of planetary gears, and what I can only surmise is a potentiometer. The Electric clutch must disengage for the motor to move, and the POT keeps track of the shaft position.
If the Clutch does not release, the motor can not turn.

Took the shift motor apart and found that a bit of case lube had made it's way into the motor and made it past the gaskets. I cleaned it all off, cleaned up the commutator and reinstalled it. Still no go and figured the sensor at the base of the unit had gone kaput.

I found a place in town with a new motor, so I replaced it $370 - no go
So now that I look at it, I think the issue is the Clutch is not disengaging, and is killing the motor.
That's probably why I've been reading about people who have had the recall done having to replace the shift motor afterwards.

Anywho, Along the way, I found I can manually select the transfer case by moving the shaft the motor engages with. As this is reachable without lifting the vehicle, it seems like a reasonable emergency ""Fix"". I'll need that to get it to the dealership...

This is starting to sound expensive - Volvo AWD Service expensive
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