OK
I used a bosch 5 spade relay ... #1 form C std. automotive 5 post relay
WIRE::
1. large gauge wire (10) from BATTERY or STARTER LUG to (ammeter) or directly to the key switch - BATT. you have this already
2. START post of the key switch to #30 of the relay.
3. ACC of key switch to anything that provides power to a feature like the heater switch to #85 of relay. See note:
4. #86 of relay to GROUND.
5. 87a of relay to HORN.
6. #87 of relay to ''S'' POST of STARTER MOTOR
NOTE:
I installed another simple ''' STARTER'''' switch on the dash for the replacement of the heater switch. you could use your parking/headlight switch. this first click of the '''starter'''' switch closes the relay to connect #30 post to #87. thus directing the voltage to complete the starter circuit from the key switch to the ''S'' lug of the starter motor. If the switch is not clicked the voltage will automatically flow from the #30 power side 12volt to across the relay contacts to #87a. @87a is wired to your horn thus when the key is turned on to START the HORN BLOWS. Sorry I do not know yet how to wire to a foot or single contact ignition switch.
HOPE this helps.
