2004 Suburban 4WD Shifting in and out of 4WD by itself
May 8th, 2019, 3:31 PM
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2004 Suburban 4WD Shifting in and out of 4WD by itself
Hey Guys,
I have a 2004 Suburban 1500 Z71. In quite a bit of research, I can't find anyone who has this issue:
We started seeing the "Service 4WD light" coming on a few months ago. Every time the suburban is started up, the switch shows that it's in 4H. When I press the "Auto 4WD" button, the switch shows that it is going back into Auto and acts like there's no problem. The lights have never blinked or gone crazy.
Besides the switch showing that it's in 4WD every time it's started, there's another problem: When driving it, it goes in and out of 4WD randomly. The Auto 4WD light stays solid, but it's switching in and out of 4WD without telling the switch. We have put all 230,000 miles on the suburban and can definitely tell when 4WD engages.
When I turn the suburban off and back on, the switch shows that it's in 4H, even though when I turn it off, the switch showed that it was in Auto.
Since I did those 3 things, the "Service 4WD" light has stopped coming on but the random toggling between 2WD and 4WD has continued.
All of the research I have done tells me that if it was a failing Transfer Case Shift Motor, it would fail to shift from 2WD to 4WD or get stuck in one position. That's very different than my problem.
Thoughts?
Thanks!
I have a 2004 Suburban 1500 Z71. In quite a bit of research, I can't find anyone who has this issue:
We started seeing the "Service 4WD light" coming on a few months ago. Every time the suburban is started up, the switch shows that it's in 4H. When I press the "Auto 4WD" button, the switch shows that it is going back into Auto and acts like there's no problem. The lights have never blinked or gone crazy.
Besides the switch showing that it's in 4WD every time it's started, there's another problem: When driving it, it goes in and out of 4WD randomly. The Auto 4WD light stays solid, but it's switching in and out of 4WD without telling the switch. We have put all 230,000 miles on the suburban and can definitely tell when 4WD engages.
When I turn the suburban off and back on, the switch shows that it's in 4H, even though when I turn it off, the switch showed that it was in Auto.
- I removed, cleaned and made sure the connections are solid with the wires under the driver's side door (everyone's first step when the service light comes on)
- Then, I replaced the actuator on the front axel.
- Then, I replaced the switch in the dash.
Since I did those 3 things, the "Service 4WD" light has stopped coming on but the random toggling between 2WD and 4WD has continued.
All of the research I have done tells me that if it was a failing Transfer Case Shift Motor, it would fail to shift from 2WD to 4WD or get stuck in one position. That's very different than my problem.
Thoughts?
Thanks!
May 8th, 2019, 4:15 PM
#2
CF Monarch
I am not expert on automatic four wheel drive systems (old-school, prefer manual shifting of transfer case) but my guess is that your Transfer Case Control Module might have gone bad. I have included a YouTube video of a man showing how to remove it near the steering column on a 2004 2004 Silverado 1500 z71, in case you decide to
replace yours, assuming its likely the same way to remove one on a 2004 Chevy Suburban 4x4:
replace yours, assuming its likely the same way to remove one on a 2004 Chevy Suburban 4x4:
