Another "service 4wd" Question

[oldspwr]

I have searched this problem high and low on this forum and have found a lot of good information. My problem is a little different, so I figured I would start a new post...

 

My wife has a 2004 Yukon with the 4.8 in it. I bought the truck with 60k and now it has 105k on it. It's really a great truck and my wife loves it. Sometime ago, I noticed the "SERVICE 4WD" message would come up. The soon as the message came up, you wouldn't be able to switch it from 2WD to AUTO, or 4WD, etc. If you shut the truck off and turned it back on, it would go back to normal with no problems

 

Two weeks ago she mentioned that the LED's in the 4WD switch were acting funny. Once the red neutral LED went on, and then it went out, leaving no LED's lit... Then more often than not, none of the LED's would be light, although the truck would remain in 2WD.

 

So like I mentioned I did a search on the forum here and realized it could be (3) things... either the 4WD switch, the encoder motion position senor or the transfer case control module (TCCM). Someone also mentioned that by '05 GM had most of the switch issues resolved, and with mine being an '04, I decided to replace with switch. So I ordered one from the dealer and installed it Friday night. I used the switch multiple times and each time you could hear the encoder motion position sensor operating (from 2WD to AUTO to 4WD to 4WD LO, back and forth, you name it, I did it. And each time it worked.

 

So on Saturday she took the truck out and "SERVICE 4WD" came back on. Now today all the LED's went out in the switch again. She shut the truck off and restarted it and it was fine.

 

So now I am looking for suggestions... The dealer wants $370 for the encoder but they are on Ebay for $200. I hate to change it only to find out I still have the same problem... Any other thoughts?

 

Thanks in advance!

 

Tom

[oldspwr]

Any ideas out there??? Any help would sure be appreciated!!!

 

Tom

[Se77vN]

I have searched this problem high and low on this forum and have found a lot of good information. My problem is a little different, so I figured I would start a new post...

 

My wife has a 2004 Yukon with the 4.8 in it. I bought the truck with 60k and now it has 105k on it. It's really a great truck and my wife loves it. Sometime ago, I noticed the "SERVICE 4WD" message would come up. The soon as the message came up, you wouldn't be able to switch it from 2WD to AUTO, or 4WD, etc. If you shut the truck off and turned it back on, it would go back to normal with no problems

 

Two weeks ago she mentioned that the LED's in the 4WD switch were acting funny. Once the red neutral LED went on, and then it went out, leaving no LED's lit... Then more often than not, none of the LED's would be light, although the truck would remain in 2WD.

 

So like I mentioned I did a search on the forum here and realized it could be (3) things... either the 4WD switch, the encoder motion position senor or the transfer case control module (TCCM). Someone also mentioned that by '05 GM had most of the switch issues resolved, and with mine being an '04, I decided to replace with switch. So I ordered one from the dealer and installed it Friday night. I used the switch multiple times and each time you could hear the encoder motion position sensor operating (from 2WD to AUTO to 4WD to 4WD LO, back and forth, you name it, I did it. And each time it worked.

 

So on Saturday she took the truck out and "SERVICE 4WD" came back on. Now today all the LED's went out in the switch again. She shut the truck off and restarted it and it was fine.

 

So now I am looking for suggestions... The dealer wants $370 for the encoder but they are on Ebay for $200. I hate to change it only to find out I still have the same problem... Any other thoughts?

 

Thanks in advance!

 

Tom

 

Dang that's tough... the dealer can't test the encoder if you pull it out?

[oldspwr]

Not sure if the dealer can test the encoder motor or not. You can hear it fine each time you operate the switch. I would really like to check the TCCM codes, but my old version of AutoTap can't look at the tranny or transfer case codes. I was thinking of going to Autozone and have them check the codes with the newer Actrons...

[[email protected]]

i had to replace the actual encoder motor in my truck, which the dealer said is pretty unusual. at first we thought it was just the sensor that was bad, cuz that is really common, but they pulled the code, and it said the encoder motor. the amps were to low or something with the ground, i dont remember. it was about $800 bucks to replace, 500 just for the part. But i had the same issues with the LED lights and what not, so i hope you dont have the same issue as me, but theres a chance its gonna be that!

[dwhults]

Next time it happens go to Autozone or Pepboys. They can scan the TCCM codes. I know my Actron scanner can scan the GMT-800 4WD codes. Once you have the code you can find the problem instead of throwing money at it.

 

I also heard the switches go bad on the GMT-800s. Might be something to look into. But get some codes first.

[derick1965]

I have a 2005 Silverado CC 4x4. It is exibiting the same exact issue or after I drive 10 mins in 2WD the Service 4WD comes on. Never does in Auto/4H/4L just 2wd. When it is not on and I run through selections all works fine. Im thinking of changing the sensor.