by geeves » Mon Jun 06, 2016 5:35 pm
What year is your bighorn?
If it has free wheel hubs then the 4wd light is controlled directly from the gearbox (auto) or gearbox selector if manual. Its unusual as most of the bighorns 92 to 95 had manual hubs but it could be correct.
As for only one rear wheel turning that would be correct for an open diff and the same should be true in the front unless you have fitted aftermarket lockers (if you have an lsd you should still be able to turn one wheel but it will be tight)
Up front is where your problem is and auto hubs make diagnosis fun.
Put it in 4wd on a flat straight section of road or drive and drive forwards about 5 meters till it goes clunk. Stop. Jack up either front wheel and turn it forwards (if you accidentally turn backwards reverse back to starting point without passing go and start again) If the free wheel is locked you will not be able to turn it. Drop that wheel and lift the other one and repeat remembering above warning. If either wheel turns keep turning it in the same direction and watch the cv joint at the same time If the cv is not turning the problem is in the free wheel hub if it is which is less likely look towards the diff.
While under the car take a look just to the left of the main diff housing to make sure that there is not a vacuum solenoid and second housing there. If there is let us know for more instructions as half what Ive just told you is wrong.
If a free wheel is faulty it can probably be fixed with a good clean and lube but if your into serious 4wding then now is a good time to consider manual hubs
Sanding your knuckles before starting work can help. That way you cant skin them