Do I need the encoder motor

NICK82

MEMBER
2001 OLDSMOBILE BRAVADA
4.3L
6 CYL
AWD
AUTOMATIC
90,000 MILES

I was wondering if I needed the encoder motor on the transfer case for my AWD vehicle? Even if it meant driving in two wheel drive.

Sunday, September 3rd, 2017 AT 12:43 PM

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,356 POSTS

If it is AWD then there should not be an encoder motor which is used to move the transfer case from two to four wheel drive and another is used for high and low gear. Are you having a problem or did you just need information?

Please let us know what happens.

Cheers, Ken

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Tuesday, September 5th, 2017 AT 12:33 PM

NICK82

MEMBER
6 POSTS

Thanks Ken!

The original transfer case, had an encoder motor on it but I do not have that motor currently as I replaced it with a salvaged model.

As far as issue, I originally swapped out AWD transfer case for 4x4 transfer case leaving the VSS unplugged. As a result, I only had first and second and my transmission is all electronically shifted. Swapped out 4x4 TC with correct AWD TC but had broken VSS on TC so could not plug in. Had first and second again but a little later I had I no gears.

After changing ATF, and filter, I verified I had no gears still. So I unplugged battery for about thirty minutes and back in and I had first for about six feet. Keeping in mind VSS is still unplugged.

I think it is VSS but not sure. Anyways, I do not have encoder motor physically with me but I did not see why I would need it anyways.

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Tuesday, September 5th, 2017 AT 12:48 PM

STEVE W.

MECHANIC
13,571 POSTS

Without the VSS signal the PCM doesn't know if you are even moving so it cannot control the shifts.
Plus you will need the encoder motor, that is not a true AWD system on the 2001, it uses the T-case to run in rear wheel drive most of the time, when it senses wheel slip it engages the transfer case and the front axle engages. Because of the way the system works it needs feedback from the encoder to operate.

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Wednesday, September 6th, 2017 AT 12:46 AM