Originally Posted by save_old_iron (Post 219544)

I would suggest we NEVER laugh at or sway anyone away from learning a new skill or learning how to use a new tool (especially a multimeter).

A simple test light will find the "hard" failures but will never pick up subtle voltage drops in starter cables, broken ground wires to coil points, dim headlights caused by 19 of the 20 strands of the headlight wire corroded away without additional "guesswork" on the part of the person using the test light. That one strand of wire left in the headlight circuit will make the little test lamp glow brightly enough but still have the more powerful headlights starving for power. This scenario may even avoid quick fool diagnosis with a multimeter. Understanding how a circuit or system works is always the best troubleshooting tool.

An ohmmeter will easily show a 2k ohm trigger terminal to ground resistance that will prevent a starter relay from engaging. A person using a multimeter will can diagnose a corroded ground connection before even taking the relay off the tractor !! A test light would have sent you driving off to the store to pickup a new starter relay as the test light would have turned on full brightness on that same trigger terminal.

Excessive voltage drop on the SG wiring? How you going to tell where the voltage drops excessively without a meter? Battery cable? Starter relay contacts pitted? Bad wire from relay to SG? Put down the light and pickup the meter.

YOU must understand what the tool is telling you AND ITS LIMITATIONS. TEST LIGHTS HAVE PLENTY !!

As someone learns and masters the use and interpretation of multimeter they will be more capable of diagnosing subtle issues a test light can't touch. Learn to use the tool and in turn learn more about the electrical system your working on. Never stop learning. Never stop acquiring more understanding about the hobby you have chosen.

p.s. When you reach a point of total understanding of the electrical system, even a test light is not needed. Give me a piece of wire with alligator clips on each end and with the understanding I gained from using a multimeter, I trust I can locate any issue in record time.