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Kenneth K

Another Engine Panel Upgrade - Pt. 1

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Here’s my posting of my recent Universal engine panel upgrade. The real nuts-and-bolts of engine panel and wiring upgrades has already been posted, thankfully, by C. Williams and T. Metzger (see CW-1, TM-1).

My write-up assumes you’ve already done Modifications A, B, and C posted in the second link. Still, having done those upgrades, a single, undetermined short disabled my entire panel (by repeatedly tripping the 30A supply fuse) during my first start-up this season. The rat’s-nest of wires behind the panel makes troubleshooting difficult, so, heeding the advice I got from this forum, I ripped out all the wiring and started over. Since I would have to eventually put it all back together, I figured I might as well do it “my” way, which, after much head-scratching, meant adding; (1) individually fused circuits from key-switched distribution buses, (2) an Engine Monitoring Panel (with oil pressure & manifold temperature warning lights and silence-able buzzer), (3) new gauges and switches (with an oil pressure gauge replacing the old ammeter), and (4) a dedicated 12ga wire-run back to the engine compartment from the key-switch. The first addition prevents a single failure or short from the disabling the whole panel (and makes the panel essentially self-troubleshooting). The last addition provides future capability to add additional “key-switched” (and fused) electrical gadgets in the engine room without having to run extra wires later on (and, it provided a place to power the two new sensors I needed for the Engine Monitoring Panel).

After studying the Universal wiring diagram and comparing it to the actual installation in the boat, three issues became apparent:

1. Though everyone knows this, you can scarcely tell from the wiring diagram that all the engine circuits are ultimately powered by the “IGN” side of the ignition switch (ie, nothing on the panel works until the ignition switch is turned on). For simplicity, I‘d rather have just seen the “IGN” post of the key switch connected to an electrical distribution bus, then to the individual circuits. Instead, Ericson thought better to use the hot posts of various gauges and switches as “buses” to distribute power (my panel had several positive leads coming off of the temperature gauge and ammeter (+) posts and another couple off of the “IGN” post itself). Yes, it works (or, it did for 35 years, right up to the point where it stopped working altogether) but this kind of a setup is hell to troubleshoot.
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My shakedown of the Universal Wiring Diagram is this: The (dreaded) trailer plug has 8 wires. But one (red) is the power source and one (black) is the ground. The light blue (oil pressure) and tan (water temp) are also grounds (with variable resistance from their senders). That leaves only 3 positive circuits to be powered from an “IGN” switch or bus (glow plugs [gray-blue], start [orange], and alternator excitation [purple]. Note: The eighth wire, the yellow-red one, after Mod B, listed in the links above, is disconnected and unused at this point).

Here’s where, at least on my boat, the diagram was off: The diagram’s #9 wire (labeled as a 14ga wire to the fuel pump) didn’t exist on my boat (instead, the fuel pump was fed from a splice into the alternator excitation/purple #6 wire. A second splice into the same purple wire fed the Hobbs meter).
[The fix: How many circuits would have to be powered from an “IGN” bus? The 3 above (glow, start, alternator excitation), plus, the fuel pump, the pos. side of the oil pressure light, the engine gauges, and the gauge lighting. (note: The #10 wire in the Universal diagram is the signaling wire to the Tachometer and runs directly to the Tach.) That makes 7 circuits, a good application for a Blue Sea Systems 5046 fused bus bar.]

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2. My original 30A fuse in the red supply wire (protecting the entire engine panel) was located on the panel side of the circuit. Seems like the fuse should be located close to its source (the battery post on the starter solenoid) so it can protect against shorts/wire chafing between the battery supply post and the engine panel. [An easy fix to move the 30 Amp in-line fuse down to the engine bay. I also upsized from 10ga to 8ga wire for the red supply wire between the starter post and the first bus-block connection in the engine bay.]

3. The trailer plugs are a commonly known problem. The one in the engine bay is easy to remedy because it’s easy to get to. The one at the engine panel is a real bear to get to (think laying on your back, head-to-stern, under the starboard cockpit seat-bottom). If you can get under there for a look, you’ll see that, on the E32 at least, the trailer-wire-run is about 2 feet longer than it needs to be. Mine was bunched up in a tight “S” pattern to take up the slack, and held up in place by about five cable ties. Considering that the panel “harness” that this wire-run plugs into is itself about 12” long, you have almost 3 feet of unnecessary wire. [The Fix: Clip off the trailer plug at the aft end of the trailer-wire-run, then take off another 18 inches, before attaching ring terminals. These terminals will attach directly to the proper switches or to the Blue Seas 5046 bus bar.]

With those thoughts in mind, I ripped everything out of the boat…..

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Updated 06-01-2019 at 12:14 PM by Kenneth K

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Maintenance and Mechanical