Why is my horn starting my 74 road runner

[flamesoldier]

Why when i press my horn is it able to start my car?!

 

[Don Frelier]

Wow, that's a new one.

Pressing the horn button makes a ground path on the horn relay.
So likely the horn relay is working.

Maybe the wire from the horn relay is attached to the start relay and not the horn?
Not sure how that would happen.

 

[Timmayy]

I wouldn't even fix it. Keep it like that.

 

[Beekeeper]

Does your horn work? If so does it sound when you turn the ignition to start position?

 

[flamesoldier]

That’s exactly what is going on, i turn ignition to start horn sounds, i press horn ignition turns over.

 

[Cheapsunglasses]

I think it’s pretty neat

 

[Nacho-RT74]

 

[Nacho-RT74]

Being serious… have you changed dash harness Or engine harness?

several wires where swaped between bulkhead blocks on 73 and 74.. even more on earlier models. So I think some wiring is unmatched between bulkhead and engine side harnesses.

wires like brake light switch test, horn, starter relay, wiper washer where swapped couple of times between them Along the 3rd gen production

74s got in fact doubled circuit the starter relay wire to feed the interlock reset button on engine bay, where on earliers was just one.

 

[rpm 340]

I had that problem 30 plus years ago. I believe it was mismatched steering column wiring, as they changed the harnesses for different years. Could be as simple as reversing the two wires at the junction.

 

[Nacho-RT74]

On this case based on the swapped functions is not posible to get mismatched wires down the column, due the diff terminal sizes

aside this, the horn button handles ground which becomes positive after the relay mounted on fuse box and ignition handles positive. Will shor out immediately

problem is at bulkhead or engine side harnesses.

based on some other problems shown on another thread, engine side harnesses are not 74, so is not matching the 74 bulkhead disposition

 

[rpm 340]

Oh, you might want to be careful as the horn probably has constant power. Your car could turn over by itself. Can't remember how I fixed it ,but it wasn't too hard. It was funny when it happened.

 

[RemCharger]

Look at the wire colors going to your start relay and go back from there.

Personally, I think it's awesome.

 

[rpm 340]

I think nacho-r/t74 is correct on this one. I think this happened when I had a fire and changed the under hood wiring harness from a junkyard car.

 

[zyzzyx]

I bought a turn signal switch assembly and the directions instructed me to change some wires
around. Oh great! I'll have to wait and see just what that does!

 

[Beekeeper]

That’s exactly what is going on, i turn ignition to start horn sounds, i press horn ignition turns over.

You horn wire and start wire are shorted together somehow for sure. By mismatched connections or bare insulation.

 

[flamesoldier]

So the problem i have is this if i use the wiring diagram from mymopar for 1974 it says yellow #9 terminal on engine bay side goes to “I” on starter relay. Then on underdash side the #9 terminal is color green-red, which runs to horn relay. This is factory wiring. Doing this allows car to start with wheel horn button, if i turn key the horn beeps does any one have a more accurate wiring diagram for 1974 ?

 

[Don Frelier]

Looks like you need to swap 9 & 12 on the interior side.
The diagram is definitely incorrect.

 

[flamesoldier]

Looks like you need to swap 9 & 12 on the interior side.
The diagram is definitely incorrect.

I did and everything works great except horn doest work when I do that

 

[Nacho-RT74]

If dash harness is untouched the problem is outside, so the fix is outside not inside. Fix the wrong, not the right.

 

[Nacho-RT74]

74 bulkhead disposition from FSM