Hi, Henry before you can diagnose any electrical component in the Starter Circuit it is "IMPERATIVE" your battery must be fully charged to 12.5 volts or more and be able to pass a proper "LOAD" test because your battery may have a preliminary reading of 12.5 volts but little or zero amperage, the battery is faulty and must be replaced. Your starter motor stays engaged because the solenoid positive plunger contact plate/disc has spot welded itself to the negative contact shoes usually caused by low battery voltage, faulty starter relay, or button. Your starter motor has two main systems the motor itself and the starter solenoid which transfers high amperage to the motor enabling it to turn over your engine, your issue only involves the starter solenoid and may be repaired without removing the starter in most cases and depending on the model of your Harley may require removing the rear exhaust pipe if it's in the way. The solenoid is the part that has a large copper stud protruding from it that the positive battery cable connects to. Start by disconnecting the battery negative cable and wrapping the cable terminal with any kind of tape so it will not accidentally touch metal and make all electrical circuits hot again, remove the starter solenoid cap, secured with 3 screws 1989 and later or 2 screws 1988 and earlier, with a screwdriver break away the contact plate from the shoes and clean/dress all electrical arc residue. In order to diagnose the starter circuit, you must start with a fully charged battery, 12.5 volts or better and be able to pass a proper load test if necessary. The battery cables and terminals must be clean and tight. The "NEGATIVE" cable is famous for corroding and or breaking inside the harness, check the terminals at both ends. Check your starter relay with a test light for continuity, it could be faulty due to corrosion and sticking in a closed configuration, another claim to fame. Finally, there is the starter solenoid, low battery voltage or faulty battery connections will cause extremely high amperage at the plate and contact shoes and rob the hold in coils of much-needed voltage. In extreme cases, the solenoid plunger plate will literally spot weld itself to the contact shoes, keeping the circuit closed and thus permanent engagement. Another scenario is unacceptable voltage drop to the starter solenoid from the ignition switch to the starter relay to the starter button, and finally to the solenoid. Remove the green wire from the starter solenoid and hook up the positive lead of your voltmeter to the green wire connector and ground the negative lead. Turn on the ignition switch and depress starter button, the voltage reading should be no more than 1/2 volt less than the battery voltage. If it is more than 1/2 volt you need to backtrack that part of the circuit with your voltmeter until you find the voltage robbing offender. Next, remove the solenoid plunger, dress the plate and the contact shoes of arching residue and make sure the contact shoes are tight and secure. If you have done all of the above, replace the green starter button wire, hook up your voltmeter to the battery and check the voltage drop when you start the engine, anything below 9 volts could indicate a faulty battery and a proper load test should be performed.
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Harley Davidson 2003 Dyna Service Manual
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