1987 Bronco II Ignition Cylinder/Switch

jtaborsky · Nov 6, 2018

I am at the end of my rope here. Vehicle is a 1987 Bronco II. I have a spare steering wheel with the shaft and all the goodies, but I hope I can avoid going down that road.

Just the other day my key became very difficult to turn and also very difficult to predict the functions. I tried replacing the key cylinder, but that didn't help. I tried replacing the switch, but that didn't help. I tried soaking everything with pb blaster, but that didn't help.

I think I have it narrowed down to the "gearbox" between the key and the switch..

My question: is there an easy way to replace that gearbox or do I have to replace the steering wheel and shaft?

This is my offroad toy, so the easier/cheaper the better!

Thanks in advance.
- Joe

jtaborsky · Nov 15, 2018

Well, I have decided I am going to convert it to push-button start, but I have a few questions. Hopefully I can get a little input from you fellas!

The keyed switch has 11 pins; 2 are labeled BATT, 2 are labeled A1, 2 are labeled A2, the remaining 5 are labeled 11, 12, ST, P1, and P2. I tested the 11-pin ignition switch with an ohmmeter to determine which pins have continuity in each key position, but there are a few pins I can't determine the function of. Here's what I've come up with (pin label - pin function):

BATT - connected to the battery; no surprise there
A1 - power to radio, wipers, and I imagine other accessories
12 - power to ECU
11 - power to HVAC
ST - power to starter

With the key turned counter-clockwise (accessory), there is continuity between the BATT and A1.
With the key turned clockwise ONE "click", there is no continuity.
With the key turned clockwise (ignition) TWO "clicks", there is continuity between BATT, A1, A2, and 11.
With the key in cranking position, there is continuity between BATT and ST.

My question is this:
There is never continuity with P1 or P2 and any other pins. What do P1 and P2 stand for? Why would they be wired to the switch if they serve no purpose?

Is there any reason why it won't work to have one toggle switch in place of "accessory", one toggle switch in place of "ignition", and a momentary switch in place of "crank"?

Thanks.
- Joe

adsm08 · Nov 15, 2018

I'm not sure about P1/P2.

Your toggle switch idea will work fine, that's basically how NASCAR does it, the only thing I would recommend is to not run everything through the switches directly, but to use a relay system.

jtaborsky · Nov 20, 2018

adsm08 said:
...the only thing I would recommend is to not run everything through the switches directly, but to use a relay system.

Thanks for your response. I have a few questions regarding your suggestion. I don't mean to sound like I am challenging you or doubting you, but I want to keep my wiring as simple as possible.

Why do you recommend using relays? Of course it is always safer to keep higher currents as far away from ourselves as possible, but there has to be a point where the added effort outweighs the potential risk. The switches I am using are rated at 20A each, so 40A between the two of them. Do you know what a 1987 ignition cylinder switch is rated for, or where I could find that information? I imagine the high-current devices would already be relayed from the factory.

Thanks again for chiming in.
- Joe

adsm08 · Nov 20, 2018

I don't know what that factory switch is rated for. I do know I have seen them melt down before.

Even 20 and 40 amp switches are going to be maxed out running multiple systems, and there are only two or three relays in the factory wiring system of an 87. It is far better, and safer to run a relay run by a switch than run a switch directly powering a device.

I know you want to keep it simple, but I'd hate to see someone put all that work into something and have an electrical fire take it out.

1987 Bronco II Ignition Cylinder/Switch

jtaborsky

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jtaborsky

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adsm08

Senior Master Grease Monkey

jtaborsky

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adsm08

Senior Master Grease Monkey

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