Push buttons vs. encoder motor

[2500ak]

Ok, so heres the dilemma. A few days ago a ground strap fell off of my firewall causing my gauges to go crazy. The transfer case clunked a few times and the light on the selector ended up on neutral (even though it wasn't) I pushed 2hi and it went into 4hi, pressed it again and it went into 2hi and now refuses to shift out of it.

Full story here

http://www.fullsizechevy.com/forums/...case-help.html

I fixed the grounds and everything else works, but I still have the service 4wd message and no response from the three buttons.

I think I've narrowed it down to an encoder motor problem, or a switch module problem.

I can get the motor for under $200 and the switch for around $70 iirc.

-----------------------------------------------------------

So what I would like to know are the symptoms of each. Namely, when the motor goes out does the light 4wd selector light flash? Or is it unresponsive.

Or when the switch goes out do any of the lights still work?

I'm banking that people have had this happen to them in the past.

Any help is greatly appreciated.

['01_1500]

I had a switch go out in my 2001 and the light stayed on but I couldn't switch into 4x4

[2500ak]

Originally Posted by '01_1500

I had a switch go out in my 2001 and the light stayed on but I couldn't switch into 4x4

Yes, thats exactly what I was looking for, ok so now I know its exhibiting the signs of the switch being out.

Now I need to know if, when the encoder motor goes out, if it will try to shift it and have the 4x4 indicator flash, then go back to 2hi. Because if it does that means it has to be the switch.

[2500ak]

Ok, that wasn't the problem new switch is in same results.

New theory, when the ground failed there were a series of clunks as though the motor was trying to engage 4wd, it didn't, but I think that it might have slipped the gears on the sensor or simply blown out the motor.

If I replace the motor, which is an expensive part, sensor and do you guys think this will fix it. These cases are solid enough that I don't think its the case, and I've never heard of a broken actuator on an nbs.

[2500ak]

Oh, and to take the motor off its just two bolts and a connector right? Will the truck be drivable with the encoder motor off?

[S/C Z71]

Fuses?

[2500ak]

Fuses are good, both under hood and cab block.

[KillerB]

Can you hear the motor moving? I've never worked on one of these yet but a stepper motor is a stepper motor. The most likely issue is that the encoder has lost its knowledge of where it is (thinking its in 2wd when it is in 4wd). There should be a way to "re-home" the system.

B

[2500ak]

Thats a really good point, before it went out it acted really confused. The ground was loose and every time I hit a bump the gauges would go out and at one point the t-case clunked twice, like it was trying to engage out of no where.

After I got down the hill the reader said neutral when it was in 2hi, I hit 2hi and it flicked to 4hi, I hit 2hi again and it clicked to 2hi. I got it to my gramma's house and played with it and it worked for several shifts. Then it stuck in 2hi and thats when it threw the [service 4wd] code.

And no, I cannot hear the motor moving

Does anyone know how to open up the encoder motor and get to the sensor? Or is it a sealed unit?

[$ilverado]

I had the same issue where i tryed to switch it flashed then went back to what it was. Replaced the button console and it worked fine.

[41canine]

I had exactly the same problem on my '99 Silverado. Instead of replacing the switch, I EASILY took it apart, cleaned the contact board and the brass buttons with a cue tip and alcohol and put it back together. Like a gummy TV remote control. Approx. 15 minutes start to finsh and it's fine. No more "Service 4WD" and all buttons work as designed. It's been about a month now and no problems.

[brandon24]

Originally Posted by 41canine

I had exactly the same problem on my '99 Silverado. Instead of replacing the switch, I EASILY took it apart, cleaned the contact board and the brass buttons with a cue tip and alcohol and put it back together. Like a gummy TV remote control. Approx. 15 minutes start to finsh and it's fine. No more "Service 4WD" and all buttons work as designed. It's been about a month now and no problems.

i did that exact same thing and mine lasted about 6 months and the light just came back on, i think i just might buy the switch this time, did you use any emory cloth or just the alcohol?

[2500ak]

Ok, turns out its the module that controls the 4wd, so a few questions.

1) where is it

2) is it hard to repalce

3) how much does it cost and does anyone know the part number

[2500ak]

Bump