1998 Tahoe 4WD problem

[SunlitComet]

sometime it will burn out from a power spike or intermittent short. just keeps tabs on it for now.

 

[trevcda]

And it blew again switching from 2WD to 4WD moving around 5 to 10mph. Replaced fuse, got 4WD drive and got out of jam but left it in 4WD. Buying more fuses. Any thoughts?

P.S. Sorry for the thread highjack!

 

[SunlitComet]

unplug the motor power from the shift motor and try shifting it again. f it still blows with motor disconnected then suspect defective wiring from the tccm to t-case or maybe the possibility, however rare, that the tccm has a fault.

 

[trevcda]

Having "exercised" it a few times since the snow hit it seems to be doing better going into and out of 4HI. I've taken to turning the key to on, letting the 4WD thing doing its thing and end up on 4HI before starting the engine and it seems to like that better than jumping in jamming on the key to start it before I've even settled into the seat. Patience; who knew?

For kicks I thought I'd try 4LO and right on cue it blew the fuse. I presume, since it blew the same fuse, the same part is the culprit here? Or is there another shift motor used to go from HI to LO?

Added: I haven't had the chance or a place to pull the plug and test that out, but as sporadic as the draw issue seems to be I'm guessing it's a motor issue. They mentioned a four pin and a six pin version. What's the difference?

 

[SunlitComet]

the np8 case you have has a 4 pin and 6 pin connector. the six pin carries signals to the tccm and the 4 pin connector carries power and brake control to the motor.

 

[flowpo]

your service 4wd light does work tho correct?

yes it works, but was not on.

 

[SunlitComet]

so where do you stand at this point?