B12 - Over Voltage Test

^ Turn ignition on, but do not start the engine.

^ Measure voltage at regulator A terminal and starter solenoid.

^ Voltage difference should be 0.5 volt or less.

Voltage difference 0.5 volt or less -- Go to B13. B13 - Regulator Ground Check

Voltage difference more than 0.5 volt -- Service A circuit wiring. Go to B2. B2 - Base Voltage and No Load Test