I rarely use the 4x4 But I get the opportunity on occasion. So far I have replaced the TCCM, Encoder motor, and the actuator on the pass side under the battery. All of these things were done at different times and fixed the problem for a little while. The truck is a 98 blazer Lt without autotrac. When I push the button to engage 4wd I can hear the encoder motor engage and every thing seems to work fine except the 4wd never actually engages. Can the front axle be engaged manually? And as a side note Does anyone know if the front wheels lock automatically in 4lo and how to test that?

Thnks for you help

Hunter

Here is a how to post that may help you.
http://www.automotiveforums.com/vbulletin/showthread.php?t=572914
The front axle locks in for 4W operation.
The actuator cable is what pulls for 4 W axle lock in.
On of the man things is good vacuum there and transfer case switch working good to turn actuator solenoid/vacuum on.

thanks I plan on hopping back into this tonight. I will try and retry these things maybe I will get lucky. I have no error lights or service lights so I think I am in the mechanical portion of the 4wd system and past all of the system checks. maybe the actuator again. is there a way to manually engage 4wd?

Manual engage Front axle or transfer case?

manually engage the front axle. As long as the encoder motor engages the transfer case engages right. or I would get some type of a code. My understanding is all of these checks are preformed before the actuator engages the axle.

Have you checked the vac lines under hood and then the 3 port vac switch on the drivers side of the transfer case (only a $15 part) and often the cause. Lines are 5/32" and on a 98 usually rotted out somewhere.

Have you checked the vac lines under hood and then the 3 port vac switch on the drivers side of the transfer case (only a $15 part) and often the cause. Lines are 5/32" and on a 98 usually rotted out somewhere.


I have not checked. I thought this was only 99+. I will take a look tonight. Thanks