Which is the power wire for the ignition of a 1989 Ford Bronco?

I've had this problem. I replaced the battery cables and ends and solved my problem.

It could have a weak or failing ignition coil. The other thing I can think to look for would be an exhaust restriction.. (clogged catalytic converter)

What about the fuel filter?? was it replaced?

Fords require 10 + volts to activate the solenoid.
A faulty solenoid, weak battery, or bad connections can cause the solenoid to click. Especially a battery with a dead cell that looks like it is charged.
If the solenoid is clicking the neutral safety switch is ok. If you are only hearing relays click, take a test light and check the 16 gauge wire on the solenoid for voltage with the key in start position.
Also jumper that post with the battery post on the solenoid to crank the engine.

It sounds like you have mixed your PRIMARY POWER
to your starter solenoid (Specifically "S" and "B" leads).

My best suggestion would be to either get a REAL
shop manual for your ignition switch... or use the
FREE wiring diagrams from BBB Industries...
Registration is required at
BBB Industries Premium Alternators Starters Power Steering Products

THIS simple REVERSAL would
allow the starter to crank... but releasing
the key would cause it to die...

"B" is on full time battery (Coming out of the solenoid)
"S" only has battery on it when the IGNITION KEY
is in the "START" position

Looking at the DRAWINGS

Savvy...?

Carnac the Magnificent

Try starting the vehicle in Neutral. If it starts and jumps from the solenoid mounted on the firewall then there is either a circuit break or the neutral safety switch is faulty or the cable is maladjusted

Just answered identical problem in another make of vehicle. There are 2 possibilities for your problem. A bad Keyswitch and/or a bad Starter Solenoid. I assume your Bronco did not start, which is a good thing. You could have damaged the teeth on the flywheel if the engine started.

You may need to replace the Keyswitch. It is suppose to send a signal to the "tickler" wires on the Solenoid, connecting the Battery to the Starter. Either the Keyswitch shorted and continued to power the Solenoid, or the Solenoid shorted and Welded a connection after the Keyswitch was turned OFF.

Remove the small wires to the Solenoid. If the Solenoid is welded internally, the Battery will spark when you try to connect the Battery cables and the Starter will spin. This would mean the Keyswitch may still be good, do not reattach the small wires yet.

You would need a testlight or Voltmeter to test each small "tickler" wire by attaching the testlight to a Ground and the other end to the tickler wire. When you turn the Key to Start, the light should Glow. It should not Glow all the time.

My advice is to replace both the Keyswitch and the Solenoid because of the wear they encountered with the malfunction. Then when you get the Bronco to start, go to Autozone or Oreillys for a Starter draw test to see if the Starter was damaged by your other problems. Both of those Parts stores test and scan for free.

Take your Bronco to an Autozone or Oreillys for a free scan. Offhand a new ignition switch would seem like a good idea, because the fuelpump should not be working in the ACC position.
If a new ignition switch does not help the fuelpump problem the pump is wired to an accessory. You need to look up the fuse info in an owners manual.

Belt, remove the the front plastic cover which covers the Timing Belt to see if the belt is stripped of teeth, same as the old Ford Pinto motor.. remove dist cap and watch rotor rotation, see if it is spinning... Ignition Modules are a major issue with those in that year also... check module also...

Check for power on the thin wire going to the solenoid when ignition is turned al the way to start possition,if so it probably won't be the same voltage as your battery, it will be lower.
You need to fit a universal relay so that the solenoid gets the same voltage as the battery when measured with a multimeter between the negative and positive poles.
If no power present on the thin wire with key turned to start possition,there is a wiring problem or broken (thin wire) from ignition switch to the solenoid.
If ignition switch is wired correctly, check if power is transfered from one of the thicker wires to the thin wire feeding the solenoid when key is turned to the start possition, on the ignition switch where the wirng is connected.

Regards
Phillip

try changing the solenoid and looking for a broken wire from yhe solenoid to the starter. if this does not work the most common problem is that the ignition switch is bad.