A good multimeter is your best tool for troubleshooting your Softail’s charging system.
The clicking sound of a starter motor is the first clue that your 2003 Harley-Davidson Softail motorcycle’s battery has been drained beyond operation. Even a fresh battery can be drained to near-exhaustion without the aid of the motorcycle’s charging system to replenish its charge. But, tracking down the cause of a charging system failure takes a fair amount of detective work, since the problems can be linked to the motorcycle’s stator, voltage regulator or both. Take your time while testing the electrical system to prevent overlooking anything that could help your determine the right course of action.
1. Remove the seat from the motorcycle to access the battery. Using a multimeter set to the RX1 range, test the battery’s charge. Set the multimeter’s red probe on the battery’s positive terminal first, followed by the black probe on the negative terminal. The battery should have a minimum charge of 12.5 volts. Charge the battery using a trickle charger if the battery’s voltage is below 12.5 volts before continuing to the next step.
2. Turn the ignition switch to the “ON” position and start the motor. Using a multimeter set to the RX1 range, test the battery’s voltage again while opening the throttle slightly to increase the engine speed to 3000 rpm. The battery should indicate a minimum charging voltage of 14.3 volts.
3. Locate the voltage regulator on the front of the motor between the frame’s down tubes. Visually inspect the regulator for damage or corrosion, especially around the voltage regulator’s mounting area. Replace the regulator if there is any obvious signs of damage.
4. Disconnect the voltage regulator from the stator on the left side of the motor. Use a multimeter set to the RX1 range to test the regulator, placing the black probe on the battery’s negative terminal. Touch the red probe to each of the voltage regulator’s pins. A voltage reading on any of the pins signifies that the regulator is damaged, replace it immediately.
5. Using the other half of the disconnect plug on the motor, test the stator for resistance. Use a multimeter set to the RX1 range, placing both the red and black probes on each of the stator’s pins in the plug. The pins should have a resistance of 0.1 to 0.2 ohms. Replace the stator if resistance is lower than 0.1 ohms.
6. Move the multimeter’s black probe from the stator’s plug to the engine’s crankcase. Replace the stator if there is any resistance indicated by the multimeter.
7. Check the stator’s alternating current output using a multimeter set to 30 volts AC. Connect the red probe to a pin the stator’s plug and the black probe to the corresponding pin on the voltage regulator’s plug. Start the motor and take note of the multimeter’s voltage reading. Ideally, the stator should be producing an AC current of 32 to 40 volts at idle. Replace the stator if the voltage reading is below 32 volts.