4 wd will not engage

[harvick fan]

i have a 2001 silverado and the 4 wd will not engage. you press the 4 hi or 4 low and you hear a clunk noise and the light blinks on the button.some say its the actuator, where abouts is the actuator located?

[vnotaro]

Try the switch on the dash first. Mine did the same thing and I had the switch replaced. Problem solved. Hope this works for you.

[SpitAndDirt]

Have someone listen to the front axle while trying to engage 4 wheel. The actuator they may be talking about is the one that locks in the front wheels to the transfer case. It should be the only cylinder shaped item on the front differential that has maybe like 4 or 5 wires coming out of it. I opted not to get the push button 4 wheel drive system myself, but the actuators perform the same function in either system.

[harvick fan]

i got under the truck and had some put into 4 hi and 4 lo and the front actuator was not doing anything.you could hear the noise from the tranfer case area put nothing up on the axle.i couldn't feel nothing move on the front actuator either. called dealer and they want $126 for a new 1, i guess i'll start with that and see if that fixes it.

[SpitAndDirt]

the acuator may not engage with the truck standing still, you may have to try putting the whole truck on jacks and then trying it. Just be extra carefull, please!! The wheels need to move a little so that the actuator can engage properly. One other thing, you may have to have your computer read for fault codes that may not set a Check engine light. But may be stored in the Body Control Mondule or Transmission Control Module. You may have one or other other, both, or neither. Some GM's are getting real computer heavy nowadays. You might only need an update for that matter. Tell me how it goes -Chris

[harvick fan]

well i just wasted $126 on the actuator and it did not fix the problem.the computer codes, do i have to have that done at the chevy dealer only or can any 4 wd place do that? should i try the codes first or try a new switch?

[Jeremy-WI]

Check fuses, there are 2 fuses on the OBS trucks for the 4 wheel drive system and I imagine the NBS are similar. On the OBS the T Case fuse powers the transfer case and the 4WD fuse powered the front axle actuator. At the connector for the front axle actuator the brown wire should have 12v any time the key is on and the light blue wire should have power any time a 4 wheel drive mode is selected

[harvick fan]

checked the fuses only had the 1 in the fuse panel labled 4 wd ,a 15 amp
and that was ok. is there another fuse some where else?