2003 GMC Sierra 4wd service light on

2003 GMC SIERRA
213,000 MILES
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JUDAS49
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My truck has auto 4wd with neutral. 4wd service light on, no codes showing, I have replaced the switch on the dash, the encoder ring, and the 4wd shift solenoid on the front diff Also tried remainving the fuse for the Control Module for thirty seconds to wake up the Module and it didn't work. Trying to figure out whatwto look at next, maybe the Transfer Case Control Module?
Aug 3, 2013 at 8:52 AM
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HMAC300
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it cold be but have it scanned by apro scanner he can turn the 4wd on andoff to figure out what is wrong. could be encoder motor on tcase
Aug 3, 2013 at 9:13 AM
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JUDAS49
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Is there a different code reader they use other than OBDII? Sounds good though, dont wnat to throw more money at it without knowing more. Thanks.
Aug 3, 2013 at 11:33 AM
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HMAC300
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the ones at auto parts store a re just basic readers they can only read the code and erase it with some freeze frame capability the pro ones can turn stuff off and on to do further checkes like modules etc.
Aug 3, 2013 at 2:44 PM