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Junior Charter Member
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Discussion Starter #1
I used the AAW harnesses. Everything works OK except the horn and the tail lights. The horn will work with the key in the off position, but when i start the car, the horn will not work at all. When I turn on the parking lights, the tail lights come on as expected, but when I move the light switch to the headlights position, the tail lights go off. Does anyone have an ideas?
 

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Senior Member
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For the tail light problem, check the switch schematic. I believe there's a way to hook up the running lights to stay on with the headlights or switch off when they come on. You may have the wire hooked up to the wrong terminal for what you want.
 

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Senior Member
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Here's the switch connector diagram. Is it possible you have the front signal parking lamp and rear tail lamp feed reversed?

 

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the problem with the horn has to be due to where your positive wire is connected. I use a relay wired with a positive that is always hot. I then run a hot wire to the relay from the "run" terminal on my ignition switch. I can't figure out how you have it wired but somehow your hot wire goes cold when your ignition switch is in the "run" position.

the same has to be with where you have the hot tail light wired
 

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Blue Oval Scribe
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9,177 Posts
HH...

The way the AAW horn relay is wired is simple. The relay gets it's power from the red wire that comes from the battery through the two-wire plug (red and purple wires). The red is hot at all times to the ignition switch and fuse box.

The relay will have two red wires going into it (power for the switching side of the relay and for the load). The relay will have a black wire for the switching side ground (this is what goes to your horn button on the dash), and a dk. green wire, which is your load output wire and goes to the horns.

Wired from the factory, the horn should work ANY TIME the battery is connected, irregardless of the ignition switch.

Either AAW has wired something wrong, or you've made changes to the AAW horn circuit.

Can you give us any more details to what you may have done or modified?

Do you have a DVOM or test light to do some voltage checks for us?

As for the taillight circuit you simply need to relocate your brown parking light wire from the "Front Park Lamp" circuit in the above diagram to the "Alternate Full Time Front Park Lamp" circuit.

The AAW harness does not have separate front and rear park harnesses, so you need to connect the brown wire to the "alternate" to have the park lights stay on after the headlight switch is pulled out to headlamps.

Many '60s cars (like my '66 Mustang) have the front parking lights go out when you go to headlights...

HTH...
Mark
 

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FFCobra Fanatic
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I used the aaw harness also. Like Mark said the way it comes you can only connect the horn one way and that is thru the ground wire. No need to wire anything at the relay other then connecting the black horn ground wire to the switch,from switch to ground(frame ground). It should work at all timeskey on or off.You mention "rear" light go out when headlights are turned on. What rear lighting schematic did you choose? AAW has 3 to choose from,one spec for the ffr when useing the supplyed head light switch. Thinking the head light switch is not wired correctly, douple check this useing a volt meter at the terminal on rear of head light switch. If you find voltage at the rear light term. on switch,then problem is in the rear harness wireing.
All these problems may also be due to a bad ground. Make sure you have good grounds,espeacally the rear light harness. A bad ground or insuficient ground will cause failure as the load is increased meaning the ground may be good enough for just the running lights but when added load of head lights is applied the ground fails to complete the curcuit.
 

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Senior Member
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1,911 Posts
Other horn possibility is that the ground for the horn or relay ceases to be a ground when the switch is in run - are both the local horn ground and the ground for the relay coil directly wired to chassis ground or a busbar, or are you grabbing a wire that "should" be ground" or that "looks like ground when the ignition switch is off"?

I'd poke around with a multimeter and verify (wrt chassis ground) your voltages. Doesn't matter if you start with the horn and work back or start at the switch and work forwards - step-by-step will find the problem!
 
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