Thanks Max, Very helpful. A keeper... Larry
On 01/04/2017 10:25 AM, Meade Dillon via Mercedes wrote:
Larry, Here is a simple analogy on electrical circuits that may help. Wires = water pipes. Bigger pipes pass more water. Water = electrical current flow of electrons. The idea is to keep the water in the pipes so that it can do some work. Amperage = water flow (higher amps = more water). Voltage = water pressure in the pipes. No pressure (no voltage), no water flow. Resistance is any obstruction to the flow of water. A switch in a circuit is like a two-position valve, either the valve is opened up to allow water to flow or closed and no water flows. (analogy can be here confusing because "closing" a switch = opening the valve to allow water to flow, while an "open" switch is really a closed valve, no water is flowing). Ohm's law: V = I*R (voltage = current times resistance). Restated Ohm's law: I = V / R [Current (measure in Amps) is equal to the voltage divided by resistance]. As the resistance gets smaller and smaller and approaches zero, the current (water flow in our analogy) gets bigger and bigger. "Short to ground" or "zero resistance" means that your pipe as a big leak, and all that water is just going to waste, and it can flow REALLY fast. "Open circuit" or "infinite resistance" means the pipe is capped off at the end, and no water is flowing. There can be plenty of pressure (voltage) but that water isn't going anywhere. Fuse = a weak point that breaks whenever the flow of water (amperage) is too high (analogy kind of breaks down here). Applying this analogy to your pre-glow system: A big pipe brings water (electrons) to the 80 Amp fuse in the relay. The relay is a switch, that has come fancy timer circuitry and is controlled by the signal from the ignition switch. No water (electrons) flows through the relay until the signal comes from the ignition switch, and then the relay "closes" and allows water to flow through the fuse and out the connector to the glow plugs. Your problem is that too much water flows (too many electrons, too much current) and the 80 Amp fuse blows. One (or more) of your "pipes" going to a glow plug has a big leak. The closer to zero your Ohm-meter reads, the bigger the leak. Hope this helps! ------------- Max Charleston SC _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
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