Transfercase defaulting to 4lo
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Transfercase defaulting to 4lo
97 f150 lariat, 4x4 (electric) 160,000 miles, 4.6 V8.
transfercase motor is defaulting to 4lo but not completely, leaving transfer case in neutral (just out of low range) disconnected shift motor and manually put truck back into 2wd, transfercase motor will not go into any other mode on its own. Keeps moving toward 4lo position... I’m thinking bad Gem or vacuum leak, not sure if it could be something else. Any help is appreciated.
transfercase motor is defaulting to 4lo but not completely, leaving transfer case in neutral (just out of low range) disconnected shift motor and manually put truck back into 2wd, transfercase motor will not go into any other mode on its own. Keeps moving toward 4lo position... I’m thinking bad Gem or vacuum leak, not sure if it could be something else. Any help is appreciated.
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Joined: Sep 2006
Posts: 7,907
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The only place vacuum is used is from the firewall to the front actuator.
Everything else is electrical driven mechanics.
4WD operation::
You request an operation from the dash switch to the GEM.
The Gem operates a relay to pass fused power to run the case motor to the requested position and stops.
.
From your description it sounds like you have a leaking windshield that has soaked the GEM.
It's located on the back side of the dash fuse panel.
If the case motor runs at all it's not power.
If turning the dash switch to 4H does not run the motor backward from either 4H or 4L the relay is not coming up to reverse 12 volt polarity to the DC motor.
Drop the motor off so you can see, and work on the cause until you get it to work as it should.
The motor position has to go to each position for the trans to engage and send signal forward to lock the front CV axle and report the action back to the GEM that lights the dash position light.
In 4L the circuit board behind the case motor that you saw has a contact to a lead to signal the computer to change shift rpm so the motor does not (rpm) trying to shift gears in 4L from the huge gear reduction.
Good luck..
Everything else is electrical driven mechanics.
4WD operation::
You request an operation from the dash switch to the GEM.
The Gem operates a relay to pass fused power to run the case motor to the requested position and stops.
.
From your description it sounds like you have a leaking windshield that has soaked the GEM.
It's located on the back side of the dash fuse panel.
If the case motor runs at all it's not power.
If turning the dash switch to 4H does not run the motor backward from either 4H or 4L the relay is not coming up to reverse 12 volt polarity to the DC motor.
Drop the motor off so you can see, and work on the cause until you get it to work as it should.
The motor position has to go to each position for the trans to engage and send signal forward to lock the front CV axle and report the action back to the GEM that lights the dash position light.
In 4L the circuit board behind the case motor that you saw has a contact to a lead to signal the computer to change shift rpm so the motor does not (rpm) trying to shift gears in 4L from the huge gear reduction.
Good luck..
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