# Service 4wd display



## jgsxr750 (Feb 16, 2006)

I have a 2005 1500 silverado 5.3 liter and i just received a message on my instrument saying SERVICE 4WD. Now my 4wd doesn't work and all lights are out. restart truck and everything works. Has anyone run into this or know how to fix? Hooked computer up and no codes come up.


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## chcav1218 (Jul 31, 2008)

My Service 4wd light has been on and off since i got the truck last april, but I;ve never had problems with my 4wd actually not working


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## B&B (Nov 4, 2006)

"Hooked up" to what kind of computer? Because if it wasn't an enhanced scanner, just one of those run of the mill low buck code readers it won't pull any code other than P series (engine) codes. You need a good scanner to read B/U/C codes. 

Most of the time it's either the dash switch assembly, a poor ground for the encoder motor (it's located on the dr side cab mount right under the door) or the encoder motor itself on the T-case. Not too often anything else in the system goes bad. A good scanner to pull the codes will lead you to what is causing the issue.


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## chcav1218 (Jul 31, 2008)

i think mine is caused by a worn out dash switch


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## B&B (Nov 4, 2006)

chcav1218;787904 said:


> i think mine is caused by a worn out dash switch


And yours is the right year for that. The '99-02's were the worse for the switches causing problems. You really should fix it before it leaves you stuck. It's a 10 minute $60 fix. Unlike a tow.


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## chcav1218 (Jul 31, 2008)

shweet. ill get on that


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## jgsxr750 (Feb 16, 2006)

"Hooked up" to what kind of computer? Because if it wasn't an enhanced scanner, just one of those run of the mill low buck code readers it won't pull any code other than P series (engine) codes. You need a good scanner to read B/U/C codes. 

Most of the time it's either the dash switch assembly, a poor ground for the encoder motor (it's located on the dr side cab mount right under the door) or the encoder motor itself on the T-case. Not too often anything else in the system goes bad. A good scanner to pull the codes will lead you to what is causing the issue. 
B & B

i'm not sure which code reader it was but i can tell you i don't think it worked very well. I currently have the truck a my local garage that i trust 100 % and they are going to pull the codes to find out what the hell is going on. Were can i find the dash switch besides local chevy dealers? all the dealers in my area are gone, closed up. would have to travel any were from 45 minutes to an hour to get to next dealer. I'm hoping it's just the switch
thanks


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## YardMedic (Nov 29, 2006)

Funny, my 2005 Tahoe is doing the same thing, and I've wondered if this was going to be a significant repair cost. This is a great thread that I just stumbled into! Thanks!!

~Kevin


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## B&B (Nov 4, 2006)

jgsxr750;788445 said:


> Were can i find the dash switch besides local chevy dealers? all the dealers in my area are gone, closed up. would have to travel any were from 45 minutes to an hour to get to next dealer. I'm hoping it's just the switch
> thanks


There's plenty of sites online that handle genuine GM parts. GMpartdirect.com and GMGenuineparts.net are just a few that come to mind. Google will find you more I'm sure.

IIRC the current p/n (it's changed several times over the years) for the switch is 12473227

Once they have the codes (if there actually are any) make sure they first check the ground that I spoke of BEFORE you go replacing parts. No point in throwing money at something needlessly.


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## jgsxr750 (Feb 16, 2006)

Well they just pulled the codes and they show codes for the transfer case and a front differencial. They rebalanced the front tires and did a wheel alignment and test drove the truck. front diff codes never came back but the transfer case one did. i went under the truck and traced the cable. While tracing the cable to the ttransfer case i mved it slightly( while truck running) and it transfered from 2wd to 4wd low. Any thoughts on bad switch?


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## B&B (Nov 4, 2006)

What were the codes specifically? Simply stating that they pulled T-case and actuator codes doesn't mean anything..you need the actual code numbers for a better diagnosis. 

But at this point with the info in your last post it sounds like the corrosion demons have gotten to the encoder motor or it's connector plug. Which is a well known common issue on those trucks when living in the snow belt. 

You can disconnect the plug from the encoder and take a peek but often times the corrosion is actually internal in the encoder itself.


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## nelson4047 (Dec 7, 2008)

b&b is right about corrosion i just did same on a 02 gm and found bad wire from encoder to switch, mice chewed it up under the hood just enough to let moisture in and turn green then you know what happens. good luck


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## jgsxr750 (Feb 16, 2006)

I called my local garage that pulled the codes from the truck and the technician that worked on the truck didn't write them down and apparently doesn't work there no more. The owner is a friend of mine and he as had issues with this guy and was completely apologetic to me and wants me to bring truck back to re-read the codes. I'm currently planning on looking into the wire for the encoder motor today. ground for it is good. I post updates later. Thanks for all the help. This is a great site everyone is on top of there game: with information.


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