Ford Muscle Cars Tech Forum banner
1 - 5 of 5 Posts

·
Premium Member
Joined
·
5,919 Posts
Discussion Starter · #1 ·
I'm looking for a 12v key on terminal for two short term power applications, a fuel pump used for priming the carb and a choke.
Q1. I don't think Acc is the same as key on, but what is the difference? I can find an Acc under the dash easily, can I just use that?
Q2. I read to use a Ford starter relay triggered by the "I" terminal or the + coil wire, but also read that relay was not good for long term usage. Also, aren't those wires only carrying 8 volts or so?
Q3. I have a hole in firewall to run a wire through, which terminal on the ignition switch is key on?
Thank you, all!
 

·
Registered
63 convertable
Joined
·
1,013 Posts
you are right about the start relay. acc is the same as on with one exception. no ignition power in acc. the wires will carry any voltage available in your car. look at wiring diagram for acc position on key switch
 

·
Registered
1964 Ford Custom 500 2 door with 289 and greendot c4
Joined
·
64 Posts
The I terminal on the relay supplies 12 volts when cranking the starter. It is not always used but when it is it goes to the ignition coil to bypass the ballast for easier starting.
 

·
Premium Member
Joined
·
5,919 Posts
Discussion Starter · #4 ·
you are right about the start relay. acc is the same as on with one exception. no ignition power in acc. the wires will carry any voltage available in your car. look at wiring diagram for acc position on key switch
Good answer! ACC it is!
and there is a fuse behind it too, something neitjher my fuel pump nor choke has now.
 

·
Registered
Joined
·
43 Posts
Please see attached 1965 Galaxie Wiring Diagram. Hope this may help.

168784
168785


Do Not Use a Starter Relay to power your devices. They were not designed to power constant power plus they draw alot of Amperage. This link will show you a relay which is design to power devices. This is a 40A if you need more you can add a second...etc in Parallel or as a individual to a separate circuit. These relays are 5in but you can get 4pin relays if you need the NC circuit. In your case order the 12V relay.

DC 12V DC 24V Waterproof Car 5Pin 40A Long Life Automotive Relay D0N3 | eBay

The fuse of the vehicle system is limited to the vehicles accessories adding devices to power higher amperage to the system will cause the fuse to blow. Not only will the fuse blow but the wires may get hot causing oxidation especially if you try to replace and increasing the fuse amps.

Please see attached. For your project Do not use/connect the center wire/connector(87a) of the relay.


168787


There is a second option by using a DC to DC SSR cost is higher but more reliable.

168788
 

Attachments

1 - 5 of 5 Posts
Top