I own a 99 chevy silverado 5.3 and one day the 4wd just quit working. I have the push button 4wd and the lights come on like it shifts but nothing happens. the front driveshaft doesn't spin when in 4wd just the rear driveline. It doesn't make any wierd noises and no service lights came on. any ideas. thanks
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Re: 99 silverado 4wd went out... transfer case?
A little tip a friend gave me in unlocking the 4wd drive on ramps or hill and then put in neutral let roll back a foot put in park and then let off the 4wd
when in 4wd the hubs get a little heated cause they need greased so they stick into position making it hard to come out of 4wd this which i spoke of i got stuck in the senerio where i almost drove home in 4wd from 300 miles away but i called my friend he told me bought this and so i thought it could help you
your hubs just locked up on you your bearings are going to need to be packed again this is normal for this
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Subject: "Service 4WD" Indicator Illuminated, DTC B2725 Set (Replace Transfer Case Shift Control Switch) Models: 1999-2002 Chevrolet and GMC C/K Pickup and Utility Models (Silverado, Sierra, Avalanche, Suburban, Tahoe, Yukon, Yukon XL) with Four Wheel Drive and NVG 236/246 Transfer Case (RPO NP8)
Condition: Some customers may comment on the Service 4WD indicator illuminating. Upon investigation, the technician may find DTC B2725 set.
Cause: The condition may be due to a intermittent fault in the transfer case shift control switch.
Correction: Important: The transfer case shift control module should not need replacement. DO NOT replace P/N 15749703 unless diagnosis points to the module as the malfunction.
Replace the transfer case shift control switch using published Service Information procedures.
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Jack up the rear wheels and put it on jack stands. Have someone get in it and put it in 4wd and drive. Release the brake. Rear wheels are spinning only right. Don't get under it but look under it and see if the front driveshaft is spinning. If the shaft is spinning but the wheels aren't it is likely a bad front axle actuator. If the front shaft isn't spinning it is a transfercase problem.
That depends a lot on how your truck is equipped. GM uses several different 4 wheel systems including AWD, Part-Time 4WD, Full-Time 4WD, and ON-Demand AWD. Then there is another version used on some trucks that is a combination of 4WD and On Demand AWD. - it gets a little confusing but each system as slightly different charachteristics.
Genericly speaking, if you have the push-buttons on your dash that say "4-HI", "4-LO", and "2HI" and/or Auto-4WD , the transfer case has an electronicly-controlled stepper motor which shifts the transfer case into the selected mode. An electric solenoid/actuator then engages/disengages the front differential for 2-Wheel or 4-Wheel modes. One push of the button and it shifts the transfer case and engages the front differential.
That's much easier than the old days when you had to stop the truck, get out (Sometimes in the middle of a big mud hole) and lock the front hubs then get back in and play with the lever in the floor to get the transfer case to shift into the desired mode.
Make sure that all 4 tires have the same tread on them, if one or more of them are different, then the 4wd may not engage. I had the same problem with my blazer, I changed only 2 tires at a time. The front tires would rotate faster than the rear ones, the gears in the transfer case won't line up right.
you have a faulty control solenoid in the transfer case this is ecm controled . the part itself can be prchased for replacement at either the dealership or at a Napa,Oreillys,etc.. please rate this thanks