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The 4WD is not working?

Tiny
ANONYMOUS
  • MEMBER
  • 2007 CHEVROLET TRAILBLAZER
  • 93,300 MILES
Sometimes when using the selector switch for auto, 4wd hi, 4wd lo, 4wd will not engage
Thursday, February 14th, 2013 AT 1:36 AM

34 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
You need to check to see if there is power to the actuator on the transfer case when that happens. If there is, the actuator may be going bad. If there is no power, then you need to check the relay and the switch to see where power is lost.

Here is the wiring diagrams for the system and the fuse location as well with the transfer case actuator.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.
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Thursday, February 14th, 2013 AT 2:38 AM
Tiny
DONALDPAT
  • MEMBER
  • 0 POST
Yes! A post that helped I looked at the wiring diagrams and saw the ATC fuse helps run the system when I replaced it bam! All fixed I love this site.
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Wednesday, December 4th, 2019 AT 4:31 PM
Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,540 POSTS
  • 2005 CHEVROLET TRAILBLAZER
  • 113,000 MILES
When I put me trailblazer in four wheel drive it does not work but it sounds like it wants to kick in what would be the problem
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Wednesday, December 4th, 2019 AT 4:31 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Check to see if there is power to the 4wd actuator on the transfer case. If there is, check the actuator. If there is no power, you need to trace the power supply to identify where the power is lost.
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Wednesday, December 4th, 2019 AT 4:31 PM (Merged)
Tiny
JOHNPER
  • MEMBER
  • 1 POST
  • 2004 CHEVROLET TRAILBLAZER
  • 140,000 MILES
The "Service 4WD " Light is on. Also the four wheel drive is not working. What would cause this?
Well Ok you need 200 characters for this question to get read. I wonder if I have 200 characters yet. Ok I will try again to type 200 characters.
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Wednesday, December 4th, 2019 AT 4:31 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
It could be several things. Since the light is on, you need to have the computer scanned to identify trouble codes. Most parts stores will do it for free. Have that checked and let me know what you find.
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Wednesday, December 4th, 2019 AT 4:31 PM (Merged)
Tiny
MARCDIF
  • MEMBER
  • 2 POSTS
  • 2004 CHEVROLET TRAILBLAZER
  • 4.2L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 110,000 MILES
Switch works, lights do what they are supposed to. There is no dashboard indicator stating "service 4WD". There is no noise when changing modes.
I have tried removing the #8 fuse for 30 seconds and re-inserting it - no change.
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Wednesday, December 4th, 2019 AT 4:32 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Have it scanned for codes might be the switch or encoder motor but you have to scan it first.
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Wednesday, December 4th, 2019 AT 4:32 PM (Merged)
Tiny
MARCDIF
  • MEMBER
  • 2 POSTS
Because I am not sure what the switch is supposed to do. When I change from 2WD to AWD, 4HI, 4LO, it always does the same thing: flashes for 30 seconds and then stops lighting. Is it possible that it is a vacuum issue?
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Wednesday, December 4th, 2019 AT 4:32 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
I dnt' think so but it could be you can check front axle that is where the vacuum goes not to tcase. Autoparts can scan for free
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Wednesday, December 4th, 2019 AT 4:32 PM (Merged)
Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,540 POSTS
  • 2003 CHEVROLET TRAILBLAZER
  • 149,700 MILES
Will not engage 4hi or 4lo or awd.2hi is the only one that works. The lights on the selector Switch blinks over the selection when I turn the selector switch on th dashboard and I can hear the motor but it will not engage the front axle in 4hi or 4lo. The light only stays lit in the 2hi mode. Also the cruise control stopped working. I changed the transfer case/encoder motor last month and still no engagement. I recently changed out the actuator and now the blazer will not drive at all.I can rev it up and get the RPMs but its almost as if the transmission has stopped working altogether. I have checked fuse #8 under the front hood fuse box and also checked fuse #48 under the rear passenger seat. Fuses checked out ok. Would the transmission stop working upon replacing a 4wd front actuator? Thank you in advance for any assistance you may be able to offer.
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Wednesday, December 4th, 2019 AT 4:32 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Are you sure the fork is on correctly. It will do this non engagement if it is not properly installed.

Roy
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Wednesday, December 4th, 2019 AT 4:32 PM (Merged)
Tiny
BILLTYLER55
  • MEMBER
  • 1 POST
  • 2003 CHEVROLET TRAILBLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 64,235 MILES
I have a 2003 trailblazer which will not go into any of the 4 wheel drive options (AWD, 4WHI, 4WHL)
It seems to be an electricle problem. The lights flashes momentarily (above the selection) and then the service light comes on. Could this be the actuator?
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Wednesday, December 4th, 2019 AT 4:32 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Scan the computer for C-codes

Check and test the ATC fuse no.8 25amp in underhood fuse block if okay-Have the transfer case shift control module and the transfer case encoder motor checked out-
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Wednesday, December 4th, 2019 AT 4:32 PM (Merged)
Tiny
TIMWITT
  • MEMBER
  • 1 POST
  • 2003 CHEVROLET TRAILBLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 23,000 MILES
My cars service 4WD light comes on and the 4WD doesn't work, then I park it in the garage over night and it works the next morning I checked the codes and no codes are present. What could be the problem?
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Wednesday, December 4th, 2019 AT 4:32 PM (Merged)
Tiny
MMPRINCE4000
  • MECHANIC
  • 8,548 POSTS
Either the transfer case control switch, shift motor, or transfer case control module.

If you are unfamiliar with these systems, have a dealer or trusted garage repair it.
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Wednesday, December 4th, 2019 AT 4:32 PM (Merged)
Tiny
TINA63
  • MEMBER
  • 1 POST
  • 2003 CHEVROLET TRAILBLAZER
  • 4WD
  • AUTOMATIC
4 wheel drive is not working the dial does not light and it doesn't engage what could be wrong?
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Wednesday, December 4th, 2019 AT 4:32 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Check the actuator on the transfer case to see if it is getting power. If it is, remove it and check it for operation. If no power, check the wiring harness for damage and the plugs for corrosion.
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Wednesday, December 4th, 2019 AT 4:32 PM (Merged)
Tiny
TRAILBLAZER16
  • MEMBER
  • 11 POSTS
  • 2002 CHEVROLET TRAILBLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 139,748 MILES
My 4WD wont come on
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Wednesday, December 4th, 2019 AT 4:32 PM (Merged)
Tiny
DAVE'S BIG BACKYARD!
  • MECHANIC
  • 262 POSTS
Check all your fuses with a test light.
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Wednesday, December 4th, 2019 AT 4:32 PM (Merged)

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