broken 4 wheel drive

[chris m]

I have a 91 bronco 351w and E4OD with manual locking hubs and the 4x4 and 4 wheel low buttons on the dash. I went on a trip to the beach and the 4 wheel drive worked fine. Went down to the beach the next day and nothing. When the truck is in park in 2wd and hubs unlocked the front drive shaft spins freely. when the hubs are locked the drive shaft locks up so I don't think its in the hubs or the front differential. I have tried pulling forward and backward to see if it would go into 4 wheel but no luck. I would be surprised if its electrical but i'm not that familiar with bronco 4 wheel drive problems. What other things should I look for electrically or mechanically? Any help would be appreciated.

 

[Seabronc]

I do believe that you have a shift motor on that transfer case which is probably not working,

Good luck,

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[chris m]

Update. Put bronco up in the air. locked hubs and axles turn. turned front driveshaft with hubs locked and frontwheels turned. But I could hold one tire still while turning the frontdrive shaft and the other wheel would turn. Acts like the front differential isn't locking up all the way or slipping. Could something be broken in the front differential? Also, still nothing out of the transfer case, no matter what I do with the shift on the fly button. I think that might be electrical. I did disconnect the module in the right kickpanel and pushed the self diagnosis button and the led flashed four times. So its probably not the ECM. Going to check the motor on the transfer case next for any problems. Any input any you have is greatly appreciated.

 

[Seabronc]

That is normal operation for the standard axles that don't have limited slip or lockers. You will find the same thing if you jack up the back and hold one we heel, the other will turn.

Have you looked at the shift motor on the transfer case? The shift motor is a common failure on transfer cases that don't have a shift lever inside the truck.

Good luck,

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