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Question:

99 silverado 4x4 question?

My 4x4 light blinks when I try to switch from 2x4 into 4x4. I have replaced the 4x4 motor on the transfer case, and a new selector switch. Not really sure if anything is making any noise under the truck. Sometimes the 4x4 will go and the light quits blinking. I do not mind spending some money on this truck as it is my all year long truck. Gotta plow snow and if I cannot get the 4x4 to work properly, I am not making any money. Any suggestions, thoughts, or comments would be greatly appreciated. Oh, I do have the push button 4x4. Also, I can sometimes hear a box behind the dash on the drivers side clicking when I push one of the 4x4 switches. It looks like a silver box, maybe 8in wide by 8in long. I do know that the selector switch wires run from it, and other wires ( I assume ) power wires run to it. Thank you again.

Answer:

First the blinking light means it has not engaged the front axle yet. When it stays on your in four wheel drive. You may have known that I just needed to say it though. You say it works sometime so we can take it that the problem is not in the mechanics of the unit. I'm thinking it a operator problem or maybe I should say a drivers misunderstanding of what happens when you put it in 4X4. Let me try to explain. The electric motor you replaced tries to engage gears that turn both the front and rear drive shafts. If your front wheels are turned or you are sitting still the gears may not mesh and the motor gets overloaded and what I think you hear clicking is a circuit breaker disconnecting the motor current cooling down and then completing the circuit again. Before you put it in 4X4 make sure your wheels are straight, put the trans in neutral then flip the switch. Back up a few feet and go forward again that will help the gears mesh and you should see the 4X4 stop flashing.
leave it in d and let the computer computer the shift points.
i would get another standard
Does yours have the auto 4x4 option? I cant remember if that was available in 99 or not till 2000. If it does then the front axle stays engaged all the time so the only motor is the one on the transfer case. Those are a little more complex than just shifting gears, they have clutches so they are more like the auto transmission and there is a lot of things that could go wrong. These also use that somewhat expensive blue fluid. Using the proper fluid is critical to these systems working properly. If its not the auto version the the transfer case is just gears and the motor that shifts. The additional part of the system is the front axle also has a locking mechanism in it that has to operate for everything to lock in and the light to stay on. That mechanism is a maybe 2 round by 4 long unit sticking out the lower passenger side of the front differential. In the mid 90's it was a heated unit that when it turned on would extend to lock the axle. These were not known to be the most reliable. They came up with a motorized replacement for them that was not too hard to install but was pretty expensive. I dont know if they ever started putting those on at the factory or not before they went to the auto versions around 2000. The aftermarket people came up with a simple bolt like piece that replaces the heater or motor unit that leaves the front engaged all the time. Its cheap and reliable. The slight downside is the front axles and such are always turning. This could cost you a slight amount of mpg and wear and tear but if you are running around with a plow your mpg stinks and you are beating up the truck anyway.

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