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4x4 won’t engage

My 4x4 won’t work on my truck. It’s a 2003 silverado 1500. I was on my way to the movie and the 4x4 worked great but after the movie it hasn’t worked since. I’ve replaced the switch, actuator and also replaced the fluids in the transfer case. My mind is going blank on what the problem could be so if anyone could help it would be greatly appreciated.

Does the 4WD light come on? Are you running in auto 4WD?

Everytime I start the truck the “service 4wd” Light comes on and it usually has the 4 low light on. It says it’s in 4 low but doesn’t act like it.

I’d recommend joining and asking at this forum, but I think you are going to need a new transfer case. Is it push button? Have you pushed the 2WD button?

https://www.silveradosierra.com/

Ok thank you, and yes it is push button and I’ve tried 2high and all the other buttons.

Be sure to check the U-joints on the rear drive shaft. When they go bad, even just a little bad, the can really do damage to the transfer case and the transfer case adapter. Be sure to check for cracks around the transfer case adapter as well, although if it is cracked very bad, it will leak all your transmission fluid out.

The faults in the transfer case control module can be read with a professional scan tool, there may be an open circuit in the wiring that is causing the fault.

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I’m more familiar with the older trucks. Exactly what did you replace? Actuator - in front axle? Switch - is that in the dash or Xfer case?

In similar vehicles it has been poor connections for the electronic controller at wherever it connects to the trans, Don’t recall enough to be more specific, you can try searching trailvoy.com

I had a similar problem on a Surburban that ended up being the transfer case motor. Have you checked all of your fuses? I also remember that cleaning the frame ground under the driver door area can sometimes fix this issue.

There’s an article on drivetrain.com that deals with diagnosing this 4wd system. I’d link it, but don’t know how. Or if that’s frowned upon in this establishment!