Inside the TrailBlazer Front Axle Actuator

Here is a look at the insides of a TrailBlazer 4WD Front Axle disconnect actuator. Note that is particularly difficult to get inside this thing due to all the locking tabs and this one had also been sealed with silicone sealer to boot.

[@kennygee2715]

I have my disconnect on the bench. I am rebuilding my engine and I am cleaning and repacking this disconnect before putting it back in. I will bench test the actuator. I just find it seems so mickey-mouse to have a little hobby motor and plastic gears operating the the axle disconnect. I guess it works though so who am I to argue?

[@thomasjbaker7688]

I would closely inspect the outer bearings that accept the passenger side CV axle stub. Also the seal there. These are a very common failure point. I have read where some have replaced the original outer bearing with one that is just a little wider but still allows the original seal to be installed. The idea is the wider bearing carries the load better?

[@grampabadger]

Yeah. I used a bunch of tiny screwdrivers to pop the case open on mine, but still couldn't verify whether it worked or not.

[@terrywilliams2860]

How do you test it

[@thomasjbaker7688]

In vehicle or on the bench? Off the vehicle you need to connect 12 Volt power to terminal D, ground to terminal B and then ground out terminal A to activate the actuator. Remove the ground from terminal A and it should retract. I have another video showing this being done but the connections are not shown clearly. kzbin.info/www/bejne/iaG5qXyGr5qihJo

[@terrywilliams2860]

@@thomasjbaker7688 I can hear the motor when I reset it but the switch for 4wd is stuck in in auto but I can engage 4wd with a screwdriver and locks in... Sometimes I can hear the transfer case motor and sometimes I don't

[@thomasjbaker7688]

@@terrywilliams2860 Is the "service 4wd" light on or has it been on before? Best is to read the codes, but a standard "code reader" won't do it.

[@terrywilliams2860]

@@thomasjbaker7688 code is C0321 transfer case lock I have switched out the switch motor part under the dash and the front actuator and still can't 4wd to work

[@thomasjbaker7688]

@@terrywilliams2860 Ahh, well the transfer case lock circuit goes to the shift encoder motor under the center of the truck. Not the axle disconnect up front. What the "lock" is is an electrically released, spring loaded brake that stops the shift motor from turning when it is a given mode and isn't being shifted. Do you have a test meter to check voltages? There is an orange wire that goes from the ATC fuse under the hood all the way down to the shift motor. This wire gives the positive side of the brake circuit power. The ground side of the brake circuit goes from the shift motor to the TCCM (4wd control module) in the left side of the dash. This wire is Tan colored. The brake is released when powered and on when not powered so when the system needs to shift then the TCCM grounds out that tan wire which releases the electric brake and then the TCCM turns the shift motor to where it needs to be,,, then disconnects the ground for the brake so that the brake is on again and holds the shift motor in place. You probably have a bad wire somewhere, either that orange wire is not getting power down to the shift motor or the tan wire is bad going from the shift motor to the TCCM in the dash. It vould also be just a bad connection.