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4WD Not Engaging - Flashing Light on Dial - 2007

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2007 Suburban 4x4 (obviously), ~167,000.

Went to kick on 4WD yesterday and couldn't get it to engage. When I spin the dial to 4HI, 4LO, or N it just flashes for ~30 secs and then goes back to 2WD solid light. If I go to Auto in flashes and locks into Auto, but I'm not sure that actually engages the transfer case until it senses slip. When I spin the dial I don't hear anything trying to engage, but not sure how loud it is, going to climb under the truck today to really put my ear to it. 

Doing quick searches it sounds like bad fuses, old oil in transfer case or something electrical. Anyway I can start narrowing it down? I checked the fuses and didn't see any blown, but also couldn't ID which one specifically would be for engaging the front axle. Oil has ~50k-60k on it so I doubt it's the culprit, car is a daily driver not on heavy tow duty.

Any help pointing me in the right direction would be great.



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Got under the truck tonight to listen.  When I got to Auto or 4HI I hear the actuator kick on, then 30 secs later it kicks on again (as the light goes back to 2WD).  4LO or N don't make any noise.  Not sure if the actuator can fall and still "work" or if that means it actuator isn't engaging the transfer case shift motor.  Thoughts?  I'm tempted to just replace the actuator as it's not a pain and relatively cheap.


Thanks again.



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Know anyone with a good scan tool?  It will be able to see the stored codes and why it's not working.  A bi-directional tool can test the dash switch and the actuators on the axle and transfer case too to make sure they're working right.

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Unfortunately, no.  I monkeyed around on all the connections to the actuator and motor and still nothing. The actuator clicks over then back with the light changes on the dial, the motor doesn't make a peep. I ordered a new motor and am going to swap it out as it doesn't look like too much of a pain. The only thing that is bothering me is I don't have any service 4x4 or other indicators on the dash. 



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  • 4 years later...

The dash switches commonly fail and you could confirm this with a scan tool. Mine triggered a Service 4wd error. A GM replacement was less than $25 if I recall. 

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