LOCATING TROUBLES IN LIGHTING AND IGNITION SYSTEM
If no charge shows on dash meter when engine is running at speed equal to 15 m. p. h., connect good ammeter in series with dash meter; if this meter shows proper charging rate, trouble is with dash meter; if it also shows no charge, connect voltmeter with generator terminals. If it indicates a very high voltage, generator is O. K. and trouble is between generator and battery.
Test cut-out and examine all connections and wires.
If lights light when engine is stopped, trouble is between generator and ammeter. If lights do not light, trouble is between ammeter and battery.
If no, or low, voltage is indicated, trouble is with the generator, regulator, or wire between generator and regulator.
If starting motor will not crank engine, make sure battery is O. K., connections bright and clean, commutator and brushes in good condition, and that starting switch makes good contact. Crank engine by hand to make sure some mechanical defect is not preventing engine from turning.
If starting motor spins but does not crank engine, pinion or drive gear may be loose, chain broken, or overrunning clutch slipping. If a Bendix drive, pinion may stick in worm due to dirt in threads.
If none of the bulbs light, examine connection at battery, ammeter, lighting switch, and wires between those units for breaks; also all the bulbs may be burned out.
If a grounded system, examine ground connection at frame.
If only one bulb fails to light, trouble must be in its own circuit. Take trouble lamp or voltmeter and test at contacts of connector at lamp. If you get current at this point, trouble is with bulb or contact pins sticking, or not long enough. If you do not get current at this point, examine fuses, connections at lighting switch and connectors; also wire for breaks.
As a short circuit on the car generally shows its presence by its effect on battery, preventing it from holding a charge, if meter shows discharge all the time, remove wire from meter or battery. If needle remains on discharge, needle is stuck; if it drops to zero, there is a short circuit or cut-out does not open.
A short circuit beyond the lighting switch will not show on the meter until switch is turned to circuit in which short circuit is located. This will cause lights to dim and show a heavy discharge on meter.
As there are other circuits whose current does not pass through meter, a short circuit in them would not be indicated on meter, but would be indicated by running down of battery. To locate, remove all bulbs, also all wires from one of the battery terminals. Connect one side of the trouble lamp to battery terminal and the other side of lamp to wires removed. Any current leaving the battery must now pass through the trouble lamp causing it to light.
1—If trouble lamp lights when lighting switch is turned off, short circuit is either in starting motor-circuit, generator circuit (or cut-out does not open), horn circuit, or in wires between lighting switch and battery, or in ignition circuit. Eliminate one circuit after another until trouble lamp goes out. Then examine circuit on which it goes out for short.
2—If trouble lamp lights only when lighting switch is on, short circuit is in circuit beyond lighting switch. Examine circuit indicated on face of switch when in position that trouble lamp lights, as switch can be divided into sections. Eliminate one section after another until trouble lamp goes out; then examine this circuit for short.