2002 Chevy Trailblazer's 4x4 control light not working. When trying to switch from 2WD to 4, nothing happens. No light, no engaging of the drives, nadda.

Assume for an instant that the transfer case is actually working. The next area to check is the hub actuators or that the front hubs are actually engaging to drive the wheels. Remember it requires both hubs to be locked in for the 4x4 to work or else if only one hub is locked then the front diff will work and all the drive will be to the wheel that is not locked in
The cost to check is really cheap. just jack the front off the ground and see if both wheels are engaged . Do this by placing in 4x4 and have a friend hold a wheel while you turn the other wheel or try to turn the other wheel. BY holding one wheel ,if the hubs are locked in then you will not be able to turn your wheel. Ensure that the transmission is in gear as if you are driving the vehicle.

Have you had codes checked ? While connected to a good scanner that will check transfer case switch to show if switch is working, and it could be the switch on the side of the transmission.

Depending on the make and model, it could be the control switch on the dash or the switch that moves the gears in the transfer case.

4X4

On these issue, there are few solved help links for troubleshooting the issue easily.-------

Click the link below: ---

No 4x4 light on dash?

http://repairhelpcenter.blogspot.com/2011/12/no-4x4-light-on-dash.html

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4X4 Truck makes roaring noise in the front end?

http://schematicsdiagram.blogspot.com/2012/01/4x4-truck-makes-roaring-noise-in-front.html

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Car will not go into 4WD high or 4WD low?

http://schematicsdiagram.blogspot.com/2011/12/car-will-not-go-into-4wd-high-or-4wd.html

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No 4x4 light on dash?

http://repairhelpcenter.blogspot.com/2011/12/no-4x4-light-on-dash.html

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4 wheel drive system will not disengage?

http://technoanswers.blogspot.com/2012/01/4-wheel-drive-system-will-not-disengage.html

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4WD light is flashing and beeping? NO 4WD high?

http://schematicsdiagram.blogspot.in/2012/02/4wd-light-is-flashing-and-beeping-no.html

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2002 Jeep Wrangler: 4WD Idiot Light is ON?

http://technoanswers.blogspot.in/2012/06/2002-jeep-wrangler-4wd-idiot-light-is.html

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Traction control switch will not engage on 4WD High or Low

http://whoisbyme.blogspot.com/2012/10/traction-control-switch-will-not-engage.html

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4WD light flashing and 4WD will engage after few minutes

http://repairhelpcenter.blogspot.com/2012/10/4wd-light-flashing-and-4wd-will-engage.html

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2008 Toyota Tundra: 4x4 Wheel Drive Light is Flashing?

http://technoanswers.blogspot.in/2012/05/2008-toyota-tundra-4x4-wheel-drive.html

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4x4 front differential will not engage the axle on ford?

http://technoanswers.blogspot.in/2012/02/4x4-front-differential-will-not-engage.html

-------

4x4 will not engage on Ford F150?

http://technoanswers.blogspot.in/2012/02/4x4-will-not-engage-on-ford-f150.html

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Dodge Ram 4x4 light keeps flashing

4X4 LOW LIGHT IS FLASHING ON DASH

http://technoanswers.blogspot.in/2012/09/dodge-ram-4x4-light-keeps-flashing.html

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Ford 4x4 front wheels will not engage?

http://technoanswers.blogspot.in/2012/02/ford-4x4-front-wheels-will-not-engage.html

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These details will help.

Thanks.

Yes larry is very correct.Try going in reverse.

On these issue,there are few solved help links for troubleshooting the issue easily.-------

Click the link below:---
No 4x4 light on dash?

http://repairhelpcenter.blogspot.com/2011/12/no-4x4-light-on-dash.html

-----------
4X4 Truck makes roaring noise in the front end?

http://schematicsdiagram.blogspot.com/2012/01/4x4-truck-makes-roaring-noise-in-front.html

-------------
Car will not go into 4WD high or 4WD low?

http://schematicsdiagram.blogspot.com/2011/12/car-will-not-go-into-4wd-high-or-4wd.html

--------------
No 4x4 light on dash?

http://repairhelpcenter.blogspot.com/2011/12/no-4x4-light-on-dash.html

------------
4 wheel drive system will not disengage?

http://technoanswers.blogspot.com/2012/01/4-wheel-drive-system-will-not-disengage.html

----------
4WD light is flashing and beeping? NO 4WD high?

http://schematicsdiagram.blogspot.in/2012/02/4wd-light-is-flashing-and-beeping-no.html

----------
2002 Jeep Wrangler: 4WD Idiot Light is ON?

http://technoanswers.blogspot.in/2012/06/2002-jeep-wrangler-4wd-idiot-light-is.html

----------

Traction control switch will not engage on 4WD High or Low

http://whoisbyme.blogspot.com/2012/10/traction-control-switch-will-not-engage.html

-----------

4WD light flashing and 4WD will engage after few minutes

http://repairhelpcenter.blogspot.com/2012/10/4wd-light-flashing-and-4wd-will-engage.html

------------
2008 Toyota Tundra: 4x4 Wheel Drive Light is Flashing?

http://technoanswers.blogspot.in/2012/05/2008-toyota-tundra-4x4-wheel-drive.html

----------
4x4 front differential will not engage the axle on ford?

http://technoanswers.blogspot.in/2012/02/4x4-front-differential-will-not-engage.html

-------
4x4 will not engage on Ford F150? http://technoanswers.blogspot.in/2012/02/4x4-will-not-engage-on-ford-f150.html

-------------
Dodge Ram 4x4 light keeps flashing 4X4 LOW LIGHT IS FLASHING ON DASH

http://technoanswers.blogspot.in/2012/09/dodge-ram-4x4-light-keeps-flashing.html

----------
Ford 4x4 front wheels will not engage?

http://technoanswers.blogspot.in/2012/02/ford-4x4-front-wheels-will-not-engage.html

-------------

These details will help.

Thanks.

if it is a turn knob that puts it in 4x4.then a wire under the truck is touching the exhaust pipe making it do this. I had this happen to mine. It will be 2 wires so they more and likely came loose.

Have your TCCM checked out. That's transfer case control module.

Check the switch on the transfer box, it could be faulty.

sounds like the punch solinoid in the front diff

Hi my name is Juan and I do own a trailblazer with the same year 2002 and I read the problem you have let me try to help you Have you try to shift to 4hi with your transmission in neutral ? the transmission needs to be in neutral in order to shift the transfer case to 4hi and the vehicle needs to be completely stooped also is your service 4wd light on?? if the light is on your transfer case needs service and it can be as simple as the switch inside your car or a solenoid that has not been detected by the computer