Front Axle Wont Engage 4x4

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Buchenrad

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Hello all. I know this comes up a lot because I have read all the other threads started on similar issues, but I could not find one that directly addressed my symptoms.

I have a 1993 GMC Sierra K1500. Recently while I was hunting my 4x4 quit working. I disengaged it and a few minutes later I tried to reengage it but it would not go. So far I have checked the fuse and it is good and the driveshaft is turning when the shifter in is 4hi, but the front axle is not engaging and the shifter is not lighting up in either 4hi or 4lo. It isnt making any noises or anything else out of the ordinary. It just isnt engaging. I am aware of the possibility that the actuator on the front diff is not working, but are there any other possible failures? Also how would I check if the actuator is working?

Thanks in advance for your advice.
 

CrustyJunker

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Any of the other failures are highly unlikely, unless the front differential actuator came unplugged or wires pulled off somehow. Change your front actuator, that will cause the symptoms of the front not coming in (obviously) and the 4x4 light from lighting up.

If I could recommend, upgrade your front actuator if you want reliability. Buy an electronic actuator (not thermal, like your factory one) and a conversion wiring harness. It can be purchased at most auto parts stores, but getting AC Delco stuff is the best quality. Rock Auto or your local dealer should have it. It'll cost more, but isn't the whole point of having 4WD is it to be there when you need it, right? Good luck!
 

thz71

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90% possibilityits the actuator. Pull it out and engage the 4x4 and see ifbit extends if it doesent unplug it and check your conector and make sure youre getting 12v if you are its the actuator. Best thing tonreplace it with is a posi loc i love mine
 

Buchenrad

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I replaced the actuator and it works again. Possibly the easiest work I have done on my truck so far. Thanks again everyone.
 
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