Installing a GP override with a momentary switch is simple, but may not be necessary if you want it to go through the glow cycle at every start. Simply move the GP controller to the fender, away from the engine (heat). The temp sensor that's inhibiting warm cycles is inside the controller.

The controller doesn't have a "trigger" (exciter) pole. The relay is controlled internally. Ign. power just starts the glow controller cycle, and not specifically the relay.

If you still want to add an override, you'll need a relay (Ford starter relay highly recommended, and cheap, but you can use your original 83 relay), relay mount hardware (screws/bolts), lengths of 10-8 AWG wire (Batt+ power and relay to GP power), lengths of 16-14 AWG wire (momentary switch), eyelet connectors (3/16 and 5/16"), and harness protection (split loom, electrical tape, zip ties, etc.). No need for a diode. It won't backfeed to the controller. The existing fusible links are inline with the GP harnesses, but you will want (need) a 10 amp inline fuse for the momentary switch power.

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