4x4 not wprking in my 98 blazer

1999 Blazer. Thing's to check. 4x4 problem. There's an actuator pump under your battery plate. Make sure its in good shape and its working proper. Next check the cable that runs from the pump to the front transfer case. Then check the actuator switch on the front transfer case. Then check the vacuum lines from the front transfer case to the rear transfer case, that should be right under the drivers side door. There's also a actuator switch on the rear transfer case witch two vacuum lines run out of. Check them also, and last check your fluid level in your transfer case. Start from the beginning to the end. Don't forget to use your 4x4 every know and then to keep it up to power. Its not like the good old days. Where a pull of the lever on the floor engaged the 4x4. I hope this helps.

Ineed to know what kind of shifting system you have. Is it a shift lever or a push button systemThe fact that it works sometimes is a good sign. So this means its not completely broken and could be a simple adjustment

Its the same thing except it says GMC on the front. The most common issues with either of them is ABS problems, wheel bearings, ball joints, intake gaskets, plugged heater cores, injector issues, fuel pressure regulators, fuel pumps, catalytic converters, wiper motors, window motors, 4x4 issues, and the list goes on.

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put in neutral !!!

your drive shaft thats turning is mabe broke or your automatic 4x4 lockers could be bad

the trailblazers are designed to shift from 2 wheel to AWD on the fly. BUT NOT TO EITHER OF THE 4 WHEEL OPTIONS. I'd suggest you get it to a mechanic to evaluate the damages.
Jer

Hi ..i had the same same problem in my k3500,check 4x4 fuse first .if thats blown replace it if blows when you put in 4x4 go under the car and unplug the actuator at the front diff.go back in the cab and put another fuse in, shift into 4x4 if the fuse does not blow this time you will need a new actuator.
thats what happened with mine and now 4x4 is sweet.i thought mine worked to at the start until i got bogged and noticed my front wheels wernt turning.

Vacume lines or vacume switch on transfer case,or vacume pod to front axle.

Your blazer is equipped with a shift on the fly four wheel drive. That means that at speeds less than fifteen miles per hour you can shift into or out of four wheel drive by simply pushing the four wheel high button. If you wish to shift into four wheel low. Stop, put the transmission into park or neutral, and push the four wheel low button. Same procedure for shifting back out. Never shift into or out of four wheel low while moving. And be careful in four wheel low. At full throttle your still barely moving, you don't want to blow your engine up!