2004 Suburban "Service 4wd" Message - 4x4 is Functional
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2004 Suburban "Service 4wd" Message - 4x4 is Functional
Hey guys,
Long time lurker, but finally made an account.
I have a 2004 Suburban Z71 with a "Service 4wd" message, and have searched through a number of threads, but haven't found anyone with my exact set of symptoms.
Pretty consistently, after 15-20 minutes of driving, the Service 4wd message appears. It used to only come up every now and then, now it comes up every time I drive the car if I'm driving long enough. Prior to the message appearing, the 4wd works fine. After it appears, the truck won't shift out of 2Hi. The yellow light next to the 2Hi stays lit, but clicking the buttons does nothing. But turn the truck off and on again, and then the 4x4 works fine. So it seems like something else in the truck is setting a flag in the computer telling it the truck has 4wd problems, and the computer won't let it shift after that point.
I've checked the fluid levels in all the cases and they're full. The buttons seem to work fine prior to the message appearing. I've seen people say its the encoder ring or the buttons, but is there something I can do to be more confident as to what's broken before I blindly start swapping parts? I don't have a tech 2 but I have a basic scanner. I'm electrically savy though, so if anyone has advise such as checking voltages or resistances, that would be awesome. I've heard you can measure outputs from the TCCM, but haven't found what to look for.
Thanks!!
Long time lurker, but finally made an account.
I have a 2004 Suburban Z71 with a "Service 4wd" message, and have searched through a number of threads, but haven't found anyone with my exact set of symptoms.
Pretty consistently, after 15-20 minutes of driving, the Service 4wd message appears. It used to only come up every now and then, now it comes up every time I drive the car if I'm driving long enough. Prior to the message appearing, the 4wd works fine. After it appears, the truck won't shift out of 2Hi. The yellow light next to the 2Hi stays lit, but clicking the buttons does nothing. But turn the truck off and on again, and then the 4x4 works fine. So it seems like something else in the truck is setting a flag in the computer telling it the truck has 4wd problems, and the computer won't let it shift after that point.
I've checked the fluid levels in all the cases and they're full. The buttons seem to work fine prior to the message appearing. I've seen people say its the encoder ring or the buttons, but is there something I can do to be more confident as to what's broken before I blindly start swapping parts? I don't have a tech 2 but I have a basic scanner. I'm electrically savy though, so if anyone has advise such as checking voltages or resistances, that would be awesome. I've heard you can measure outputs from the TCCM, but haven't found what to look for.
Thanks!!