4WD Service light on, replaced TC Motor and more???

[jkeating86]

I bought a 02 GMC Envoy SLT recently had a buddy look at it and we found that the, well I am not sure of the exact name but the 4wd controller in the front. The shaft had the end brocken off. So I replaced that is was $92. Once we put it in and put the fuse back in it began to fire over and over again. That is how we assume it was brocken. So wse thought the only thing that could cause it to do that is the transfer case motor. So I ordered one for $200 and replaced it. I put the fuse back in and the serivce 4wd light is still on. Do I need to reset it somehow or is there something else I should check. The light on the 4wd control flash when you first start it but then they all go out and when you turn the knob nothing happens. Thanks also is there anyway to read why the 4wd light is on I have a Matco 9001 scan tool but it dosnt read the 4wd light. Is a special scan tool required or something. Thanks

[MTPockets]

So you replaced the front axle disconnect (AKA, shift on the fly actuator)? The other major 4x4 electronics on these trucks is the encoder motor on the transfer case and the dash switch itself. Seems like the most common failure items are the dash switch and the encoder motor. The easiest PM you can do for these systems is turn'em on/off once or twice a month.

G/luck
Joel

[trlbzrss]

I remember on my 04 TB 4 wd that sometimes when you first start it that the 4 wd light on the switch will flash until it checks everything and then it will stop on the selected range. If the light goes off and doesn't show any range then what I did was stop completely and shift into neutral and switch the selector at least one click either way. You can hear the solenoids switching and if everything is all right the light will come on in the selected range. At times my light would not come on if I had switched ranges and not noticed the light and that usually meant it DIDN'T switch and was still in the original range so I had to shift into neutral to complete the shift. I hope this helps some.

Rich Little Rock
sold 04 TB 4 WD
06 TBSS 2 WD Summit White

[jkeating86]

Does anyone know how you can scan the 4wd light or how to turn it off. Also if you have to reset the lite to get the 4wd to work again when you replace something.