Question about installing Ford keyless entry

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Apr 12, 2006 | 08:02 AM

01f350

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From: Scranton, PA

Question about installing Ford keyless entry

I just purchased a Factory Ford keyless entry system for my truck and I have a question about the wiring. It seems for items like the horn, door locks, and dome light, there are wires from the keyless entry module which connect directly to each of these items and then there are wires which connect to either a 12v source or a ground depending on the polarity for each of those items. Can someone explain to me what these wires related to the polarity do? And do they have to be hooked up? The last aftermarket system I installed didn't have any wires for polarity and I am not sure if they are necessary.

Thanks

Apr 12, 2006 | 09:09 AM

EnviroCon

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From: Milky Way Galaxy

The only hook-up that I can think of that requires a 12 volt source, switched or constant, would be the power for the module (constant). The chassis ground would also be for the module itself. What specific hook-ups are you referring to?

Apr 12, 2006 | 09:30 AM

01f350

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From: Scranton, PA

Well for example, when hooking up the horn. There is one wire from the module that taps into the horn wire in the steering column. Then there is a second wire and the instructions say hook this wire up to a ground or a 12v source depending on what the polarity of the horn wire is. I have no idea what this means or if I need actually hook these wires up? And I am not referring to the main 12v and ground wires. Has anyone come across this before when installing a factory unit?

Apr 12, 2006 | 10:16 AM

EnviroCon

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From: Milky Way Galaxy

That is unusual for a Ford branded RKE to require 2 hook-ups for the horn. The last one I installed on a friends truck about a year ago (I used to install alarms back in my Army days as a side job) had 1 horn hook-up. It was, I believe a brown/black wire from the module to a blue wire at the steering column. It's not uncommon for aftermarket systems to have 2 horn wire's at the module to accommodate both + and - horns. But you still only hook-up one wire, depending on the polarity of the horn wire. The other horn wire from the module is just capped off and not used. Make sure that's not what the instructions are saying, i.e. use the wire that suits your needs, not both. In this case the horn wire on a SD is - polarity, so you would only need to hook-up the - wire.

Apr 12, 2006 | 12:00 PM

01f350

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From: Scranton, PA

Well according to the instructions, I would splice the one wire directly to the horn wire at the steering column and the other wire would have to be grounded beacuse the horn is -polarity. I also have to do this for the door locks and dome light. It doen't make sense to me? Can you explain this +/- polarity thing and how I can check the others to see what polarity they are?
Thanks

Apr 12, 2006 | 12:07 PM

rwilimo

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From: NJ

The reason they do is to fit more vehicle's. If you have a horn that needs a negative trigger than you ground the input wire of the alarm so the internal relay sends ground. Now say you have positive trigger locks, then you would connect the input wire to positive.

Back in the day before alarm modules had these extra wires, most all alarm outputs were negative. If you needed a positive trigger for anything you had to wire up external relays, more work, more mess, more money.

Apr 12, 2006 | 01:05 PM

EnviroCon

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From: Milky Way Galaxy

Quote:

Originally Posted by 01f350

If that's what the instructions say go with it. If you don't have a vehicle specific wiring diagram, you can get one here. This will tell you where the wires you need are, color, and polarity. It's always best to check the wire with a multi-meter to make sure it is what they say it is.