battery hooked up backward, wires crossed somewhere or it could be the solenoid.
the bronco needs to have the ground wire connected from the battery to the body. if you replaced the battery and disconnected that ground it simply won't start.
does your bronco have an external voltage regulator if so i would take it and have it checked
Take it to your local auto parts chain store. Most of them will check your battery and alternator for free.
All kidding asside, The + side of the battery is connected to the= starter,alternator,solenoids ect ect ect. All kidding asside, The + side of the battery is connected to the= starter,alternator,solenoids ect ect ect.
Check your alternator, that would be the main problem i think because the alternator charges your battery when in use, and with a bad alternator, means that your car is runnin soley off the battery and does not recharge the battery. Look into getting a new alternator. try testing the alternator at a local auto parts store, another test you could do is start the vehicle , and while it is running take off the battery cables, if motor turns off immediatly then your answer is that you have a bad alternator
To replace the alternator in a 1989 Ford Bronco II, start by disconnecting the negative battery cable to ensure safety. Then, remove the serpentine belt by loosening the tensioner. Next, disconnect the wiring harness from the alternator and unbolt it from the engine. Install the new alternator by reversing the removal steps, ensuring all connections are secure before reconnecting the battery.
it could be the control module
What is inside a battery ? Rocky_B - See my entry here for more things you might want to check: http://wiki.answers.com/Q/What_could_be_wrong_if_the_battery_light_stays_on_and_the_battery_still_runs_down_on_a_1996_windstar_after_installing_a_new_battery_and_alternator
To test the alternator on a 1993 Ford Bronco, you should remove the negative battery cable first. This helps prevent any electrical short circuits while you work on the vehicle. Once the negative cable is disconnected, you can safely test the alternator and its connections. Always ensure that the vehicle is turned off before performing this procedure.
idle air controler
Start the car, unplug the battery the alternater should power the car. If it dies the alternator is bad. You can also get it checked at any parts store.
Under the hood, behind the battery