Probably a really easy answer to this one but I need to know. I was done installing the newly made wiring harness in the '46 Ford. Everything worked like it should except for the detail that nothing happened when I tried to start the motor. I am not very confident when working with the electrical system, but I tried to troubleshoot it. It has the original-type relay in it. I began with with unhooking the cable that comes from the starter key, from the relay. I hooked the cable to one of the connectors on the voltmeter, and the other voltmeter connector was hooked to ground. When I turned the ignition key I got a a reading, so that worked like it should. Then I put the voltmeter on the post (on the relay) where the starter key cable goes, and got a reading right away without turning the key. Can that be right? After that I put the voltmeter connector on the post with the fat cable that goes to the starter. If I have figured it out right I should get a reading when turning the key, but I didn't. Have I figured it out right when I suspect there's something wrong with the relay? Is there another way to test the relay? Thanks, Christer
A relay is used to keep from running large wires through the ignition switch. There is a heavy wire from the battery to the relay, and from the relay to the starter. When the ignition is turned to start, the wire from the switch feeds the relay, closing the circuit, and allowing juice to flow to the starter. When the key is released, the flow stops. The relay is grounded to the inner fender to make a circuit for the key wire. You should have a reading from the key switch between the wire and ground when the key is turned to start or the button is pushed. No reading when the key is in the RUN position or the button released. There should be no reading between the large posts on either side of the relay unless the key is in the START position or the button pushed. There should be no reading between the key wire post and ground for voltage without a wire from the key switch or button. Make sure that your voltmeter isn't in the Ohms position for reading continuity. This explains relays workings... http://electronics.howstuffworks.com/relay.htm Mutt
It's when I do this test that I get a reading on the voltmeter, so I guess there's something wrong with the relay after all. The relay is properly grounded and all the cables are in their right places, so I've ruled out that. Mutt, thanks for the help.
If you have the ORIGINAL relay; and the "start" function is now on the key; (instead of the original PUSH BUTTON on the dash) your using the WRONG relay. You need an INTERNALLY GROUNDED relay. (if your system is 12 volts, a standard late model relay will do the trick) Key starter switches put out 12/6 volts and the correct relay is GROUNDED ALL the time. The key switch powers the relay. Push button starter relays have VOLTAGE PRESENT ALL the time and the push button grounds it.
Ok, that explains it. Replacing the push button with a key switch is the only modification I've done to the starter system. Before I replaced the system it worked like a charm. I'll take a trip to the garage and test it, but I think Digger Dave is right. Are there any internally grounded 6 volt relays I can use? Otherwise I'll just stick to the push button until I convert to 12 volts. Thanks, Dave!
If when you turn your keyswitch to crank, and you switch voltage that's good but the "place where the wire lands already has voltage" so maybe you should be switching negative. Take a look at things again, maybe try jumping the relay post to negative, see if the starter engages.
Just got back from the garage, and Digger Dave was right. There was nothing wrong with the relay, but with the key switch setup. I reinstalled the starter button and it fired up instantly. Hooray! I had no idea there was two kinds of relays, ain't it great to learn something new?
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