Starting Motor Solenoid - Test
Note: The graphics that are illustrated in this section refer to the solenoids that are 24 VDC. Solenoids that are 12 VDC use the same procedure, but only one battery that is 12 VDC is used.
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Required Tools     | ||
---|---|---|
Part Number     | Description     | Quantity     |
6V-7070     | Digital Multimeter     | 1     |
225-8266     | Ammeter Tool Gp     | 1     |
4C-4911     | Battery Load Tester     | 1     |
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Illustration 1 | g00713118 |
Basic solenoid circuit |
A basic four terminal starting motor solenoid circuit is shown in Illustration 1. The two windings that are found in the solenoid are the hold-in winding and the pull-in winding. The windings can be checked with the following procedures.
Hold-in Winding Test
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Illustration 2 | g00713128 |
Hold-in winding test |
- Refer to Illustration 2 in order to make the connections to the solenoid. Disconnect all other leads to the solenoid.
- Close the switch. Observe the reading on the multimeter. Use the battery load tester to adjust the battery voltage until the correct voltage is obtained. Refer to Table 2.
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Table 2 Voltage
Specifications    Model     Operating Voltage     Measured Voltage     37-MT     12V     12V     37-MT     24V     20V     41-MT     12V     10V     41-MT     24V     20V     42-MT     12V     10V     42-MT     24V     20V    
- Observe the reading on the clamp-on ammeter. Refer to Table 3 for the correct amperage.
Note: A high reading indicates a shorted winding. A low reading indicates excessive resistance.
Show/hide tableTable 3 Current Specifications     Model     Operating Voltage     Measured Current     37-MT     12V     23±2A     37-MT     24V     6.75A
max    41-MT     12V     23.0A     41-MT     24V     14.6A     42-MT     12V     23.0A     42-MT     24V     14.6A    
- The hold-in winding can also be checked by measuring the resistance. Disconnect the batteries. Select the "200 Ω" range on the multimeter. Connect one of the leads of the multimeter to the "S" terminal and connect the other lead to the "G" terminal. Refer to Table 4 for the correct resistance reading.
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Table 4 Resistance Specifications     Model     Operating Voltage     Measured Resistance     37-MT     12V     .50 to .56Ω     37-MT     24V     2.96 to 3.48Ω     41-MT     12V     .50 to .59Ω     41-MT     24V     1.37 to 1.77Ω     42-MT     12V     .50 to .59Ω     42-MT     24V     1.37 to 1.77Ω    
- Replace the solenoid if any of the above readings are incorrect.
Pull-in Winding Test
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Illustration 3 | g00713129 |
Pull-in winding test |
- Refer to Illustration 3 in order to make the connections to the solenoid. Disconnect all other leads to the solenoid.
- Close the switch. Observe the reading on the multimeter. Use the battery load tester in order to adjust the battery voltage. Refer to Table 5 for the correct voltage.
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Table 5 Voltage
Specifications    Model     Operating Voltage     Measured Voltage     37-MT     12V     12V     37-MT     24V     20V     41-MT     12V     10V     41-MT     24V     20V     42-MT     12V     10V     42-MT     24V     20V    
- Observe the reading on the clamp-on ammeter. Refer to Table 6 for the correct current value.
Note: A high reading indicates a shorted winding. A low reading indicates excessive resistance. To avoid excessive heat, do not leave the switch closed for more than 10 seconds at a time. The current will decrease as the heat increases.
Show/hide tableTable 6 Current Specifications     Model     Operating Voltage     Measured Current     37-MT     12V     36±2A     37-MT     24V     89±5A     41-MT     12V     56.5±4.5A     41-MT     24V     92.5±7.5A     42-MT     12V     56.5±4.5A     42-MT     24V     92.5±7.5A    
- The pull-in winding can also be checked by measuring the resistance. Disconnect the batteries. Select the "200 Ω" range on the multimeter. Connect one of the leads of the multimeter to the "S" terminal and connect the other lead to the "Mtr" terminal. Refer to Table 7 for the correct resistance reading.
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Table 7 Resistance Specifications     Model     Operating Voltage     Measured Resistance     37-MT     12V     .17 to .19Ω     37-MT     24V     .64 to .70Ω     41-MT     12V     .11 to .15Ω     41-MT     24V     .43 to .49Ω     42-MT     12V     .11 to .15Ω     42-MT     24V     .43 to .49Ω    
- Replace the solenoid if any of the above readings are incorrect.
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