Starter Relay

You SHOULD HAVE (must have)

1....A factory shop manual and or wiring diagram
2....A multimeter, and in this day and age, NO excuse, ZERO
3...A 12V test lamp, and I like incandescant rather than LED
4...At least a couple of alligator clip jumper leads

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3 terminal relays: Stick shift before 70

4 terminal relays: Automatic all years, and stick shift after 70

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The huge nut terminal is a junction/ power terminal and one contact

The big "square" looking screw terminal is the other contact and has a rather large wire going to the starter solenoid

The flat spade flag terminal is the trigger wire from the key in "start" usually yellow.

The three terminal relays MUST be grounded as the coil ground goes to the case

The second flat spade on the 4 wire relays is the ground side of the coil, and on automatics goes to the center terminal of your neutral safety switch, which is ground in park or neutral

Stick shift 70/ later cares, the second flag terminal goes into the interior through a separate firewall wire/ grommet and connects to the clutch safety switch which grounds that terminal when the clutch pedal is depressed. The ignition switch in "start" then powers the relay

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TROUBLESHOOTING:

If it will not crank with the key, listen for any sound, "thump" of the starter solenoid, buzzing, or light click of the starter relay. Open your window, the hood, and listen

If no click at all, make sure the relay is grounded, if 3 terminal, or if auto move the shifter back and forth and listen while twisting the key to start Same if stick/ clutch safety

If no joy remove the neutral safety wire, ground that relay terminal and try again.

If nothing jumper the two large bare relay terminals. If it cranks you have a wiring/ relay problem.

Making sure the 3 terminal is grounded, or grounding the 4 terminal with a jumper wire, jumper power to the remaining flag terminal. This should cause engine to crank. If engine cranked when jumpering the two large terminals, and not while doing this last, replace the relay.