View attachment 78713 Just installed a ESRS box on my 20' Bowrider with the 305 cu. in. with Multi Point Injection. Many thanks to the kind folks at SeaRay who included a complete schematic in the owners' manual! Thanks also to the kind folks at Boatstore.com who provided the best prices, fast shipping and allowed me to return the display unit mentioned below. The injection fuel lines are charged by an electric fuel pump to 42 psi (might be more with a bypass back to the tank reducing to 42 psi) whenever the ignition is on and this is a fire concern. My boat had the factory halon bottle and a green light by the ignition showing the bottle was charged. http://www.clubsearay.com/index.php?threads/halon-auto-fire-extinguisher-replaced.95932/ The green LED is powered up by the purple ignition lead and grounded by a green/white wire going back to the bottle pressure switch in the engine compartment. When the bottle discharges at 170 degrees in a fire, the circuit is broken and the green light goes out. The ESRS box is mounted on the vertical partition by the driver's knee by four bolts whose heads are shown in the first thumbnail. Don't spin those stainless machine screws too fast with your drill/driver or they will gall and seize. I used the existing green/white wire to the pressure switch on the bottle for the ESRS box and incorporated the existing green light rather than installing a separate display requiring a 2" hole in the dash. The ESRS box is full of normally open relay switches all grounded by the green/white wire. The coils on the relays are energized by the ignition switch accessory (red) and ignition (purple) leads. When the bottle discharges. the ground through the pressure switch is lost and all the relay switches open shutting the engine and the blower down. To ground the ESRS box, I used a black wire provided in the dash for the radio and panel illumination. The idea is that the engine, including the 42 psi electric fuel pump, should turn off when you have a fire. The blower should also turn off as it would otherwise evacuate the $300 worth of fire suppressing gas your system has dumped on the fire. Ignition input (relay coil +) is the purple lead, also jumped to the switching lead on the relay (the arrow). While my SeaFire box depicts the circuits as normally closed, they are normally open. The blower circuits designated by the ESRS box are also controlled by the ignition input lead. Instead, I controlled the blower with the auxiliary control circuit using the red accessory lead as input. We should run the blower before starting the engine and I think it would be better to do so with the key in the Accessory position so as to avoid charging the fuel lines to 42 psi with fuel pump actuation. I interrupted the yellow blower leads at the fuse box as the dash control switch sends digital 5 volt signals to the mux module which can't be controlled with a simple relay. All connections were soldered. Used ring terminals throughout. My procedure is to dip the bared wire end in rosin flux, insert it in the terminal, crimp, and then solder. I believe the solder gets sucked into the terminal just like sweat soldering pipes. Crimping alone is inadequate for boats in my opinion. For an override switch to continue boating if I am still afloat after a fire, I used a SPDT toggle switch behind the dash. Center terminal is grounded to the ESRS box while one side (normal) is connected to the existing green light and the other (override) is attached to the pressure switch-green/white wire terminal on the ESRS box. I used the marked ground and pressure switch terminals for the benefit of any future techs performing repairs. Two of the YRB terminals are jumped internally to those connections but I did not use them as there is no standard wiring format for displays and I hope to avoid future confusion. My SeaFire box has a Viking Yachts parts number and differs from the Seafire Mark V schematic I downloaded which differs from the FireBoy display I considered using. For commercial use, only the designated display would pass C.G. inspection. Maybe that's why my unused Viking box only cost $55 on Ebay w/o a display. If there is a fire, the FM-200 I have substituted for halon will be discharged by the melting of the thermal fusible link in the sprinkler head. The extinguisher's pressure switch will open and the engine and blower will shut down. The green light will go off. The photo shows the factory legend from the original halon option: "Light off-Unit discharged." I will call the Law and/or towing and ask them to stand by. After 15 minutes and making sure the sides of the engine compartment are cool I will cautiously peer in and try to figure out why I would not be an idiot to turn it back on. Opening the hatch dissipates the suppression gas, admits oxygen, and risks an explosive rekindle. Assuming I find a broken wire or something innocuous, I will reach behind the dash and throw the override switch (I will put a neat Dymo label on the front to remind me of the hidden switch). The boat will then start but the green light will be out. A SeaFire or Fireboy display/override could have been used as the YRB wiring is easy enough to trace. However, the displays just seem awfully busy and prone to confuse with their 2 bottle depictions, a horn, green/red lights, and a relay type override rather than a simple toggle as in earlier iterations. I really don't want the subject of fire to be brought up by a goofy display while pleasure boating and I am happy with my concealed toggle and the factory green light.