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Old 04-29-2006, 07:23 PM
gltm gltm is offline
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99 S10 blazer 4wd not working

Thought I should ask you guys about this one as well since I seem to get such good advice here. When you push the button on the dash to go into 4wd it blinks a while and then the service 4wd light comes on on the dash. If you push the 4lo button, you can hear something in the transfer case move, but still no 4wd and the service 4wd light comes on. Once you go back to 2wd the light goes off and it runs fine in 2wd.

I was told by a dealer that it was a sensor or a motor either of which would be $400 to fix. I was told by a parts guy that it is a $14 dollar switch on the transfer case. Who has it right and can I handle fixing it myslef. I really dont want to go without it this winter.

Why did they get rid of the shifter for 4wd, my c10 is twenty years old and by God when I pull that lever i am in four wheel drive, no sensors or computers or motors involved!!!!
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Old 04-29-2006, 10:15 PM
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make sure before pushing the 4Lo button that you put the shifter on the column in neutral. It's not on the fly 4x4 like 4Hi is. While in gear, I've had a few people tear things out on the transmission.

Otherwise there is a sensor and solenoid that can be replaced if thats the culprit.
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Last edited by justen; 04-29-2006 at 10:18 PM.
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Old 04-29-2006, 11:22 PM
gltm gltm is offline
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Justen,

I learned the neutral thing back in my younger years with another guys truck!! I am in nuetral when I try to go to four low, and I dont think anything in the transmission or transfer case is messed up. Is there a way to tell what is wrong? Do you know how hard they are to switch out? Really appreciate the help.
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Old 04-30-2006, 12:27 AM
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You should check the actuator/solenoid make sure it's moving. (older style is mounted under the battery, newer style is mounted on the transfer case) Sometimes if that doesn't lock the front hubs you could have a problem, even if it sticks. Sometimes it sticks and will have a long delay. Theres a sensor down there that can go haywire but usually that will trigger codes or mil light.

Shift motor/encoder attached to the transfer case. It is controlled by the TCCM-transfer case control module. When you push a button to select a drive mode, the TCCM determines which way the shift motor/encoder has to turn in order to shift the transfer case into that mode. When the TCCM commands the motor to turn, you can hear relays inside the TCCM activate. The TCCM is located behind the passenger side kick panel. The LED in the switch that you pushed should flash momentarily, then go on steady to indicate the transfer case is in the selected mode. When the system malfunctions, you can check the TCCM for fault codes. Under the instrument panel on the drivers side and to the left of the steering column you should find the diagnostic connector. Place a jumper from pin 13 to a good ground and turn the ignition switch to RUN. Now watch the three switches. Their LEDs will flash a code. There are only four codes. If all the LEDs flash one time only, there are no fault codes. If only one code is present, it will flash repeatedly with a three second delay in between.

Sometimes you can take the encoder/shift motor out and clean it. And it will work fine again. If that doesn't work, then a junkyard would be cheaper then a $420 part from a autoparts store. I would check things out for sure. before throwing money into it. Actually all these parts mention above aren't bad to replace. A shift motor takes me around 20-30 minutes.
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Last edited by justen; 04-30-2006 at 02:02 AM.
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Old 05-06-2006, 12:11 PM
james3189w james3189w is offline
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i brought mine to a shop and they fixed it for a little under $100
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Old 02-14-2011, 09:15 PM
brandonmillsap brandonmillsap is offline
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Re:

Quote:
Originally Posted by justen View Post
You should check the actuator/solenoid make sure it's moving. (older style is mounted under the battery, newer style is mounted on the transfer case) Sometimes if that doesn't lock the front hubs you could have a problem, even if it sticks. Sometimes it sticks and will have a long delay. Theres a sensor down there that can go haywire but usually that will trigger codes or mil light.

Shift motor/encoder attached to the transfer case. It is controlled by the TCCM-transfer case control module. When you push a button to select a drive mode, the TCCM determines which way the shift motor/encoder has to turn in order to shift the transfer case into that mode. When the TCCM commands the motor to turn, you can hear relays inside the TCCM activate. The TCCM is located behind the passenger side kick panel. The LED in the switch that you pushed should flash momentarily, then go on steady to indicate the
is in the selected mode. When the system malfunctions, you can check the TCCM for fault codes. Under the instrument panel on the drivers side and to the left of the steering column you should find the diagnostic connector. Place a jumper from pin 13 to a good ground and turn the ignition switch to RUN. Now watch the three switches. Their LEDs will flash a code. There are only four codes. If all the LEDs flash one time only, there are no fault codes. If only one code is present, it will flash repeatedly with a three second delay in between.

Sometimes you can take the encoder/shift motor out and clean it. And it will work fine again. If that doesn't work, then a junkyard would be cheaper then a $420 part from a autoparts store. I would check things out for sure. before throwing money into it. Actually all these parts mention above aren't bad to replace. A shift motor takes me around 20-30 minutes.

great post! does anyone know how much it would cost to replace a transfer case switch? Thanks for sharing
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Old 02-19-2011, 07:27 PM
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Depends who is doing it. DIY maybe $60 or under. Good place to check is rockauto.com
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Old 02-21-2011, 05:28 PM
Gearhead52 Gearhead52 is offline
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This is an old one....

I just got a 97 Blazer and my electric shift 4WD didn't work either. I got it cheap partialy because it didn't work but here's what I found. I learned this stuff on another forum which has been real helpful.

The transfer case has 2 things in it that will prevent it from going into 4WD a vacuum switch which seldom goes bad and a motor that shifts the case into 4low which is a $400 part new, $150 used. These do go bad but not that often. There is a computer that is located below the radio in the dash that controls it all.

The other problem area is the vacuum lines and vacuum motor on the front axle. The vacuum motor pulls on a cable that shifts the front axle into a lock position.

Check to see if the vacuum motor under the battery box is getting a nice strong vacuum signal and if not fix it.

Next, reset the Transfer Case Control Module by pulling off the battery cable and wait for several minutes then reconnect the battery and turn the ignition switch on then off 5 times in a row. This resets the TCCM. Then try to engage the 4WD.

This is what I did and was thinking that how would this fix it but it did. 4WD worked all winter so far.

If the TCCM can't figure out where all the parts in the driveline are and what position they are in it will flash an error in the buttons and will not engage 4WD. Doing this process will reset the TCCM.
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