Bronco will not start

Okay, did you run your jumper cable to one of the 2 large bolts on the relay, or to the much smaller bolt?

I specifically asked this question two different ways before, so that I would understand what you did. Please read very carefully and answer clearly, or we're going to provide mistaken answers based on mistaken responses.

Yes, there are ways to test those switches, I'll write up a set of instructions for you this evening.

Do you have a manual or an automatic transmission?

Sorry for the confusion. I'll try and be specific.

Aft of battery there is the main relay or starter relay depending on who you are talking to. It has 4 terminals, 2 big and 2 small. The big terminals are positive and negative. The two small terminals are labeled S and I. There is a smaller red with blue stripe wire that connects to the S.

To make the motor start I turned the key to run, jump a wire from S (while leaving that wire plugged in) on the small post to the positive on battery.

From my reading the red/blue wire goes from that post to a NSS > ignition control module > ignition key cylinder. So my guess is that it has to be a problem with 1 of those 3 items.

My bronco has the C5 Auto.

Okay, now we're on the same page.

(P.S. Those big terminals aren't + and -, but more like Input and Output, both +. But we're not dealing with them. Also, that relay is often called a "Solenoid" by some people, to add to the confusion.)

I'll get some instructions together for you later. Are you familiar with measuring voltage and resistance with your meter?

Kind of, but I am certainly not a wiz on my volt meter. Electrical is my kryptonite, but I am trying to wrap my head around it.

Thanks for all the help!

Okay, first off, it's not the ignition module. The ignition module gets power from the red/lt blu wire, the same as the relay; it doesn't supply power.

Basically, 12v power has to follow this path to get to that post on the relay. Something's keeping it from getting there.

1 Starts at the battery and goes down the red wire
2 Passes through fuse-link C (green) and goes down the blk/org wire
3 Passes through fuse-link E (orange) and goes down the yellow wire
4 Passes through the ignition switch (when in the "Start" position)
5 Goes down the red/lt blu wire
6 Passes through the NSS (when in Park or possibly Neutral)
7 Goes down another red/lt blue wire
8 Connects to the starter relay to cause the relay to send power to the starter.

We know that point 1 is good, because if it wasn't, there would be no power anywhere in the truck, including cranking the starter.

We know that point 3 is good because that yellow wire provides power to the entire ignition switch; if it were bad, then the truck wouldn't keep running once started, with the key in the "Run" position. If power gets to point 3, then we also know that point 2 is good.

So, to test point 4: Begin by disconnecting the red/lt blu wire from the starter relay. Set your test meter to "Resistance" or "Ohms" or "Ω". If it has different ranges, select the smallest one (especially if it has a speaker or note or ear symbol next to it). Touch the two probes directly together, and take note of what reading you get (you may also get a beep from the meter, that's useful). That low number and the beep indicate a continuous circuit; or no broken or corroded wires or bad switches. Take the steering column cover off and disconnect the ignition switch connector. Locate the terminals on the switch that correspond to both yellow wires and the red/lt blu wire. Put one probe on one of the yellow terminals, one on the red/lt blue terminal, and reach up with your third hand and turn the ignition switch to "Start". If you get that low number or the beep, then the switch is good. If not, try the other yellow terminal and the red/lt blu terminal. You only need one yellow terminal to be good. If the number is just a tiny bit higher than your original reading, that's OK too.

To test point 5: Put the ignition connector back on (make sure all the terminals in the connector engage properly and don't push out the back). Set your meter to "Voltage" or "V", and if it has ranges, pick one that's just larger than 12. Unhook the connector for the NSS; it's probably under the truck by the transmission. Turn the key to "Start" again (either have a friend help, or wedge a block against it, or something). Put the red probe on one of the connector terminals on the wire harness side, and put the black probe hard against the truck or transmission body, preferably in a clean spot (you have to get past any rust or paint or crud with the probe tip). Your meter should read 12V or close to it. If not, try the other terminal in the connector. One of them should read 12V when the key is turned to "Start".

To test point 6: Set your meter back to resistance, like you did in point 4. Put the transmission in Park. Stick one probe in each terminal on the NSS. You should get continuity; that low number and beep.

To test point 7: Reconnect the NSS connector. Set your meter back to Voltage like you did in point 5. Put the red probe in the connector that hooks to the relay, and put the black probe on the negative battery terminal. When the key is turned to "Start" you should read 12V.

To test point 8: Finally, hook the red/lt blue wire back up to the relay and try and start the truck. If you had a loose or dirty connector somewhere in that path, there's a good chance you fixed it just by taking it apart and putting it back together.


Let me know if any of that doesn't make sense, or more importantly, at what point in the test you don't get the results I specified. If you have trouble getting a reliable result, let me know; there are alternate ways to test some of these things, but they're awkward.

Wow awesome instructions thanks!

Give me a couple days to work through this, just got back from backpacking over the weekend. I will let you know what I find.

So it is the NSS. I have power at the plug and when I jumped the red/blue to red/blue key works again. That is a project for after my wedding and honeymoon in a few weeks. Just going to leave it jumped for now! Thanks for all the troubleshooting help!!

Sounds good. Just be careful that you don't try and start it unless you're in Park or Neutral, or it might end badly.

Lol yeah might take me on an unexpected ride through the fence!