Ford CMP horn wiring

[david moore]

I have a couple of electrical/wiring questions re my F8 Cab 12.
The horn (original) has only one wiring terminal. I believe that this should connect to a solenoid ( or relay - same thing?) that is itself connected to the battery. The horn button grounds and activates the solenoid such that current flows to the horn. Right?
The wiring diagram in the manual shows the horn wired via the starter solenoid but surely this can't be right? Can that solenoid provide two diffferent functions independantly? Mac's Auto sells horn relays- so is this what I need? No mention of such on the wiring diagram. How does the horn operating current get grounded?

Two questions re the starter solenoid itself. Is the small terminal on the side the connection to the starter button on the dash?
Finally, I'm using two batteries- a 12V just for the starter via the starter solenoid - it makes starting so much easier - and 6V for the rest. I know that the starter motor can take 12V if used sparingly - which is the case since it starts first pull on 12V - but is the solenoid ( meant for 6V) OK for use with
12V?

Cheers
David Moore
Kingston

[sth65pac]

Q1 Incorrect,

Positive is sitting through the starter solenoid at ALL times, You provide an earth which is REALLY the Positive (return path) via either the starter button (to start) or a feed for the horn.

When you depress the horn, power is fed from the battery through the coil, and then to the horn. When depressing the starter button, then an 'earth' (return path) is provided.

You are thinking positive seeking. Think negative seeking and it is very easy... IF you read the circuit diagram you might note it is a Positive Earth vehicle ... Not negative earth...As used in modern vehicles.. (except them British things. ...Morris Jags etc etc)

Change the Positive Symbol on the circuit (on the battery) to a negative and the circuit will make sense. Reference. R2 Ford Manual (CMP Vehicles).

Q2. No . You should use a 12V solenoid/relay. Buy a 1960's model one..Ford F100/ F250/ F350 type one. and you will be OK.. the trouble is with a 6V one, you are at 200% capacity on current. E=IxR.... They are not expensive... and you will not have a fire or worse still the white smoke escapes from the wire and the truck no longer goes...

Ian
Bring it over & I will wire it for you!

[david moore]

Hi Ian
Thanks for great advice and info.
Wish we didn't have a few thousand miles and an ocean in the way or I'd have the vehicle at your place for wiring in a shot!
I'd happily pay someone to do it!
The original wiring was completely butchered- I do have a NOS harness from Dirk but the wiring colours don't match the diagram in the book at all so I'm wiring as I go just enough to get it going. I don't have a complete vehicle anywhere near to compare to.

Cheers

[sth65pac]

Must be a Chev loom then... PM Me Direct with your email addy & I will email you the two Manufacturer's Circuit diagrams. They are too big to add here in MLU.

Ian