3-21
Figure 3-18.—Starter motor and solenoid.
MAINTENANCE OF SOLENOIDS
If you suspect that a solenoid is not working properly, the first step in troubleshooting it is a good
visual inspection. Check the connections for poor soldering, loose connections, or broken wires. The
plunger should be checked for cleanliness, binding, mechanical failure, and improper alignment. The
mechanism that the solenoid is connected to (actuates) should also be checked for proper operation.
The second step is to check the energizing voltage with a voltmeter. If the voltage is too low, the
result is less current flowing through the coil and a weak magnetic field. A weak magnetic field can result
in slow or poor operation. Low voltage could also result in chatter or no operation at all. If the energizing
voltage is too high, it could damage the solenoid by causing overheating or arcing. In either case, the
voltage should be reset to the proper value so that further damage or failure of the solenoid will not result.
The solenoid coil should then be checked for opens, shorts, and proper resistance with an ohmmeter.
If the solenoid coil is open, current cannot flow through it and the magnetic field is lost. A short results in
fewer turns and higher current in the coil. The net result of a short is a weak magnetic field. A high-
resistance coil will reduce coil current and also result in a weak magnetic field. A weak magnetic field
