Can anyone tell me if there is a positive and negative side to a starter relay?
I'm talking about the one on the fender that the positive battery cable comes too and the negative cable runs to the starter. I took all of the wires off the thing last fall to work on the truck and now can't remember which side the positive cable came off of. I hooked everything up and the truck runs but the relay gets so hot it's ready to melt the coating off of the cables. Could I have them on backwards or do you think I should be looking elsewhere for a problem??

 

before anyone asks, this is on a 1958 f-100 but I've put a 1969 big block in it. Any help is greatley appreciated.

 

You indicated that you conected the positive to one side and the negative to the other side. Disconnect the negative immediately if not sooner or you'll have a big fire. You should hav a positive cable coming from the battery to probably the right side of the solenoid as you're looking at it on the firewall. on the left side, there should be a cable that goes to the starter. These are both positive. There should be a smaller wire that goes to the starter switch. The terminal for this wire should be at the top of the solenoid as it is bolted to the firewall. If you connect the negative and positive together on a switch, the cables will burn in half when you turn the switch to the on position. The negative should be connected to the frame as the electricity flows from positive to negative. In a negative grounded system. However, you need some sort of load in between. Hope this helps and please don't burn your truck up.

 

Jeff;

Are you talking about a stock relay or have you changed from 6v to 12v?

The coil of the relay should not heat up like you stated, do you have a good ground connection and check all wiring for damaged wires. If the fuse is holding, try to measure the current draw on the circuit, if you have a meter. You would have to have a meter in series, but it will draw full current, make sure your meter is rated for a the circuit load! It sounds like the circuit is drawing too much current, because of: wrong voltage, too much resistance due to faulty wiring, or damaged relay.
Hope this helps.

Tom

 

The guys are correct about the wiring.
Large terminal on one side goes to starter, only has power when starter is turning.
Other large terminal goes to battery positive, has power all the time. Also there may be a few other wires on it, this is just a convinient place to pickup 12 volts to feed other circuits. Just as easily could be attached to battery positive, but looks neater on the relay.
One small wire to the small terminal, could be labeled "S" this closes the relay and causes relay to send 12 volts to starter. Only powered when key is turned to start.
If there is another small terminal, labeled "I" it may or may not be used, depends on the type of ignition system installed. Sends 12 volt out to ignition system when starter is turning, used with electronic ignitions mostly.
Ground for the relay is provided by its mounting bolts.
If a wire/terminal is getting hot it is most likely caused by high resistance, meaning loose/dirty/corroded connections or wires. Wherever the heat is where the problem is......it could also be as simple as too small a wire from the battery positive to the starter relay.