Has anyone come across this? I bought the truck used-no warranty, and about once a week on start up the service 4x4 light flashes for about half a second then goes out. I haven't used the 4x4 all summer. When I do engage it there is a short grind and a bump and then it works fine. They say you can put it in 4x4 on the fly but I never chanced it above about 30mph. Oil is good and it runs quiet and smooth when its in. Dealer claims nothing is wrong, no codes etc. Just want to know what that light is about. Thanks

Not sure what year your truck is but this part is available on Eric's site (www.gmdieseltech.com (http://www.gmdieseltech.com)).



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<TD vAlign=top>2003 model year trucks were notorious for kicking on a service 4x4 light. If yours is one of them, a likely cause is the position sensor in the encoder motor on the side of the transfer case. Normally a C0327 code will be stored in the Transfer Case Module when this is at fault. I recommend having truck properly diagnosed before replacing this part. Usually this is the only problem when an encoder motor fault is suspect

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<TD vAlign=center height=25>Choose your transfer case, codes can be found on the RPO label in the glove box</TD>
<TD vAlign=center>&lt; name="product_options[Transfer Case]"&gt; <OPTION ed value="0">NP1</OPTION><OPTION value="1">NP8</OPTION></> </TD></TR></T></T></TABLE></TD></TR>
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<TD>ADD TO CART &gt;&gt;http://www.gmdieseltech.com/store2/skins/default/en/images/cart.gif (javascript if (isValid()) document.add_to_cart.submit()) </TD></TR></T></T></TABLE> Edited by: baimpala

I had the truck scanned with the tech scanner at the dealer and no codes were present. The light doesn't stay on but just flashes for a split second. If you aren't looking for it you will miss it. I have got in the habit of checking the message ctr. on start up and only very intermittently the check 4x4 light flashes.

You sure that's not just the lamp test? I thought the same thing about the wait to start light. . . After I'd just shut down the engine and it was nice and warm, the wait to start light will blink at you every time. . . Just a thought.


Dennis