2005 Suburban service 4wd message truck is in 2 wd

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My suburban is stuck on 2wd with a message that says service 4wd , I changed the switch but nothing , ground looks Ok, haven't cleaned it fuses are fine, so any help will be appreciated. thank you all
 

swathdiver

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My suburban is stuck on 2wd with a message that says service 4wd , I changed the switch but nothing , ground looks Ok, haven't cleaned it fuses are fine, so any help will be appreciated. thank you all

You can throw parts at it or find someone with a good scan tool to read the code(s) as to what is wrong Steve. You still have the actuators on the transfer case and front axle and they may just need resetting.
 
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You can throw parts at it or find someone with a good scan tool to read the code(s) as to what is wrong Steve. You still have the actuators on the transfer case and front axle and they may just need resetting.
I actually have a friend with a snap on tool I will see if there's any codes as my regular scanner didn't get any codes , how can I reset the actuators?
 
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So the results are in and I have a code C0321. Most searches says encoder motor sensor
 

TJ Baker

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I have a series of pictures taken during the job. The biggest annoyance to me was having to remove the front driveshaft to get the shift motor unit out. Most folks replace the whole unit. I would only recommend replacing the sensor by itself if you have both the time and patience for the job AND you know the rest of the shift motor is sound. It would truly suck to do all this and then discover it was not the real problem. I verified my sensor trouble with a tech 2 but it can also be checked out with a DMM and the schematics.

The primary trouble with these is a degradation of the resistive materials of the sensor by many hours of vibrations where the metal pickups ride in the 2wd position. Here's a look at mine where I have opened up the sensor. (I enjoy seeing how things actually work). The resistive material has been wiped clean in this picture but I left the buildup of crud on the pickup.P1090164.JPG P1090167.JPG

The result of this is a fluctuating return voltage signal which prevents the TCCM from determining the current position of the Transfer Case Shift Motor.

P1090170.JPG
 

TJ Baker

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It also doesn't help that a little fluid, grease or whatever seeps in there and fouls the sensor.
 

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