115 HP, 1972 Evinrude Starting Relay

When replacing the Cranking Motor Relay, I discovered that the battery negative is used to energize the Relay.<br /><br />Why did the Manufacturer use this method rather than energizing the solenoid from the battery positive? <br /><br />Were they trying to save the cost of a wire? <br /><br />Was it a form of safety? Or what? <br />They certainly did not save wire, because the negative ground is as accessible as the battery Positive.<br />anders1@telusplanet.net

Re: 115 HP, 1972 Evinrude Starting Relay

Anders..... That engine has a charging system and if you have 12 volts negative connected to the battery side of the starter solenoid, you have blown the charging systems rectifier as that component will not tolerate reverse polarity even for a split second.<br /><br />I assume you're checking the polarity with a volt meter rather than assuming the polarity is reversed due to the color of the wires? If you're not using a volt meter, do so to make sure.<br /><br />I've seen some boaters hook up the cables at the battery backwards, and rather than correct that error, they then hook up the cables at the engine backwards to compensate. If this is the case, disconnect the cables at the engine, correct the error at the battery, then connect the cables at the engine properly.

Re: 115 HP, 1972 Evinrude Starting Relay

Usually there is four wires off the starter solinoid. two thin ones and two thick ones. On my motor, one of the thick ones (RED) goes to battery positive. The other thick one (Also RED) goes to the starter motor. One of the thin ones (red I think) goes to the ignition switch and goes +12V when key is engaged to the start position. The other thin wire (black) goes to an ignition interlock switch which goes to ground when the throttle is close to the idle position.<br /><br />Now this certainly doesn't mean that yours isn't wired differently, but I believe it to be fairly standard.<br /><br />Good luck,<br />Mike