2004 Chevy Silverado No 4WD--No "Service 4WD"--No

ADBAKER

MEMBER
2004 CHEVROLET SILVERADO
V8
4WD
AUTOMATIC
102,000 MILES

Hi, hoping you can help. Here's what I know.

I do not have the service 4wd message at the DIC. I can here the transfer case shifting between 4hi, 2wd, 4lo. When in 4hi, the front driveshaft is locked, the front axles are not, they spin free. When in 4lo, it definitley goes into low gear but same problem as above, front axle not engaged. I've pulled the wiring harness at the front diff actuator. I get voltage at the brown wire and no where else when in 4hi. Should I get a reading at a different location or is a 1 time signal sent to the actuator, so I need to be reading voltage at the time of the shift? Or is my reading above correct and I simply need a new actuator.

Thanks

2 Replies

JACOBANDNICKOLAS

MECHANIC
109,858 POSTS

You should get a signal when shifting. If the power continued, the motor would keep running. Remove the actuator and make sure it is working.

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Friday, December 18th, 2009 AT 1:44 PM

ADBAKER

MEMBER
2 POSTS

I pulled the actuator, its working properly, shifts out and holds when I hit 4hi/low. I swapped in a known working actuator as a test as well, still no engaging. Everything seems to be working properly. I couldn't engage the 4wd by manually pushing into the shift tube and spinning the passenger side tire/ trying to spin the driveshaft. I'll be pulling the shift tube when I get a chance, sometime next week.

Thanks very much for the answer

Adam