94 4x4 No 4 High Electroninc Transfer

[poppaduck]

I would like to start out with apologizing for the I'm sure repeatedthread. I'm new to the forum and just don't have the time to search all the post to find the cause of my problem. When I press the 4 High button the light led comes on, the instrument cluster indicator light comes on, and I can hear the relay click in the rear of the truck. Unfortunately there is nothing happening in the transfer case. This is only happening with the 4 High. 4 low is working like a champ. I have rebuilt the LF hub because of a bad bearing. Has anybody encountered this before? What was the fix.

Thanks

 

[DeRocha]

How did you determine 4H is not working but 4L is?

You need to confirmed that after going into 4H the front drive shaft doesn't rotate. If the shaft doesn't rotate in 4H but does in 4L then the T-case is busted. If the drive shaft rotates in both 4H and 4L then you have a hub failure.

 

[poppaduck]

When I switch into 4 Lo I can here the transfer case engage and the front wheels grab like they should. When I switch into 4 Hi I do not hear any engagement front wheels do not grab. Is is possible for hubs to work in 4 Lo but not 4 Hi?

 

[JDraper]

Nope. If hubs work in one mode, they'll work in both. The hubs work independently of the transfer case and engage due to the rotation of the front axle. I'd say you have a tcase problem.

 

[poppaduck]

That's what I was expecting. Is it possible that the transfer case motor is not moving far enough on 4 Hi for the engagement to occur, but is able to get past that in 4 Lo. The 4 Hi worked the last winter but the Left Front hub would lock and unlock. Investigating the unlocking was when I discovered the bad hub bearing.

I guess that I need to get on the ground with a multimeter and a wiring diagram and have the spouse operate the switch for me to see if I'm getting propper voltage/amps.

 

[DeRocha]

That's what I was expecting. Is it possible that the transfer case motor is not moving far enough on 4 Hi for the engagement to occur, but is able to get past that in 4 Lo. The 4 Hi worked the last winter but the Left Front hub would lock and unlock. Investigating the unlocking was when I discovered the bad hub bearing.

I guess that I need to get on the ground with a multimeter and a wiring diagram and have the spouse operate the switch for me to see if I'm getting propper voltage/amps.

It doesn't work that way... all the electronics are doing is rotating the T-case selector shaft from 2H ->4H ->4L and then back. Since you indicate the 4H dash and button lights come on it means the T-Case has correctly shifted into 4H (I assume the 4H gear is gone). As such when you press the 4L button the shift motor rotates the T-Case selector to 4Low thus using the low gearing which you indicate does work..