Hi pauly. I don’t have any direct experience on your engine’s circuitry but I do have considerable experience troubleshooting electrical systems in general and have a good understanding of electrical theory. I agree with Glenn; for troubleshooting, it’s probably more expedient to follow the voltage, rather than use continuity checks that can be very confusing to inexperienced troubleshooters. I suggest that you start with an accurate shop diagram of your wiring system. As you test each point in a systematic way, record your observations on the diagram.
There are a few points to keep in mind when trouble-shooting:
A functional circuit has a complete path from positive to negative, otherwise current would not flow. So, when test measurements are made between points in a closed circuit, it follows that you are going to see some degree of continuity at every point to every other point in the circuit.
It makes sense that test metering devices by nature must not themselves change the electrical values of the circuits being tested. Voltmeters (and multimeters when set on voltage scales) have a very high internal resistance. They are constructed this way so that they do not divert a significant amount of current, since the meter’s internal circuit becomes part of the circuit being tested and could change the current flow, perverting the test results.
Meters, when reading current flow (amps), are typically connected in series with components, so they must have a very low resistance so as not to impede the current flow under test and pervert the test results. It’s very important that connecting ammeters be done carefully so that the test leads do not actually create a short circuit, blowing fuses or damaging the meter.
Meters most commonly test between only 2 points. It’s very important to use a consistent reference point when checking voltages. Don’t assume that the engine block has a perfect connection to the negative or that the negative cable has a perfect connection to the negative battery post. Use the negative post itself whenever possible as a reference point or make very certain that the point to which you are connected is cleanly connected to the post.
A failing connection point in an otherwise complete circuit may not be “open”, but have a relatively high resistance across the connection. The high resistance will impede current flow and cause equipment to be non-functional, but a simple voltage test may not reveal the problem. A circuit must be “loaded” by current flow for the high resistance of a failing connection to show a drop in voltage from one side to the other. This is often the case with corroded battery terminals that will not allow high currents to flow to start the engine. If tested with a voltmeter while not attempting to start the engine, a voltmeter may indicate full voltage is available. This is also why a completely discharged or failing battery may show near full voltage until a load is applied.
I hope this is some help - Grandad
