4x4 problems NP243

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heavrolet9894

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I just traded of my 97 K1500 Z71 with a NP241 for a 97 K2500 with a NP243 and the 4wheel drive is inop. When I turn the key to the on position all the lights come on and then go off like they should including the 2hi, 4hi, and 4low lights on the push button shifter. Once I start the truck none of the lights on the shifter are on. If I push 4hi I can hear a clicking in the dash and I can hear the motor in the transfer case working and the 4hi and 4low lights flash twice then sometimes they both stay on and sometimes they both go out. When I push 2hi I hear the same clicking noise and the transfer case motor turning but half the time the 4hi and low lights will flash twice and stay on. No matter what I do the 2hi light will not come on at all once the truck is running but like I said the bulb flashes on when I turn the key to the on position without starting the engine so I know its not blown. I really just want to make sure I'm not driving around in 4wheel drive.
 

JonZ71

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what are you laughing at? if it was the actuator the lights would just blink and go back to 2wd.
 

bggrnchvy

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Tranfercase motor? :lol:

Sounds like an actuator issue.

Yes, the motor on the 243 that makes it a 243 not a 241.

Its all one part, could be that or the switch.

No, it's not. There's a front diff CAD actuator like all the IFS trucks, but the 243 has a seperate motor on it that changes ranges and locks the front shaft in an out like the manual lever on the 241 does.

IMO, see if the actuator is getting power. If it's getting power in what should be 4wd, check it for functionality. If it's working right, you should suspect the t-case shifting motor.

If the t-case is locked in 4wd due to a failed motor but the actuator has the collar retracted, the front shaft is spinning but you're in 2wd.
 

bggrnchvy

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Could a bad actuator motor cause a very loud clunk when switching to 4 low?

Very loud is kind of subjective. It does clunk pretty solidly when it locks the planetaries in.

If it's doing that I would definitely test the the voltage output from the switch panel. Those things are pretty common for failure.
 

RHamill

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Very loud is kind of subjective. It does clunk pretty solidly when it locks the planetaries in.

If it's doing that I would definitely test the the voltage output from the switch panel. Those things are pretty common for failure.

Oops, I meant to say transfercase motor, not actuator motor.
 
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