Question about 2001 GMC Yukon XL
This light comes on and will not go off. Is it OK to drive? What do I do?
Mine was dash 4x4 switch. Buttons got stuck or something. A little bit of electronic wash on and in the buttons and in back at the wires and its working fine now
Posted on Dec 26, 2013
Replace the transfer case shift control switch . there is a TSB # 02-04-21-004 released in april of 2002 , on your unit , you may also find a code # B2725 set in the body control module , fualt explination - fualt in transfer case shift control switch . GM part # 15709327 , also he is an excellent link on how to replace it yourself .
i know its a siverado but its the same process . that will fix ya !
Posted on Jan 08, 2009
I had a similar problem with
the Service 4 Wheel Drive light which came on intermittently then became more
consistent in the message center display. It would go into 4 wheel drive if the
message center did not display the Service 4 Wheel Drive message in the message
center, but not when the message was displayed. I found the transfer case
switch module in the dash was defective, and it has been working with no other
problems for three years.
Posted on Jul 22, 2010
I had this light come on in my 2003 tahoe it ended up to be the transfer case motor (encoder motor) was bad. I got one out of a used part store and the light went off right away.
Posted on Apr 26, 2009
i had the same problem with my 03 silverado.it's a internal problem in the 4WD actuator.my truck would go in 4WD sometimes and some other times the service 4WD light would come on and it would not got in..after a while it wouldn't go in at all so i replaced the actuator and it fixed the problem..
Posted on Dec 31, 2008
On the full size, the front actuator is electric, not vacuum.
When in 4wd mode, a switch on top of the transfer case conducts 12 volts out to the actuator. Wire #50 (brown) is the 12v feed, and it conducts to the light blue wire (#900) to the actuator.
When shifted out of 4wd, the switch opens up and no voltage goes to the actuator.
Check voltage at the connector for the front actuator (at the front differential - it looks like a large bullet that threads into the front diff.) If it has 12 volts, the actuator is the problem. If it does not have 12 volts, check the transfer case switch and the power feed to the transfer case.
I'll assume it is the actuator, if the plug to the actuator is getting 12 volts when in 4wd.
The way this actuator works, is it is a sealed chamber that gets heated by voltage. When it heats, the pin in the end swells and pushes a shift fork in the front differential. The shift fork engages a spline on the passenger side of the differential, and boom! you have 4WD.
GM offered an upgrade to this actuator that is a motor instead of a heated device. However, it requires a small harness addition, a spacer, and a new actuator. It is about a $150 to $200 option.
If I were you, I would buy a new heated actuator. They are available at most auto parts stores, and are about $90. They are also on eBay for about $55 plus shipping. These are very easy to change - just thread out the old one, and thread in a new one.
Good luck, That actuator is usually the problem 90% of time but check the fuse first in your fuse box.
Posted on Dec 30, 2009
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