26SI Series Alternator – 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.

Table 1
Required Tools    
Part Number     Description     Quantity    
6V-7070     Digital Multimeter     1    
225-8266     Ammeter Tool Gp     1    
4C-4911     Battery Load Tester     1    



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



Illustration 2 g00713128

Hold-in winding test

  1. Refer to Illustration 2 in order to make the connections to the solenoid. Disconnect all other leads to the solenoid.
  1. 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.

    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    

  1. 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.

    Table 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    

  1. 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.

    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    

  1. Replace the solenoid if any of the above readings are incorrect.

Pull-in Winding Test



Illustration 3 g00713129

Pull-in winding test

  1. Refer to Illustration 3 in order to make the connections to the solenoid. Disconnect all other leads to the solenoid.
  1. 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.

    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    

  1. 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.

    Table 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    

  1. 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.

    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    

  1. Replace the solenoid if any of the above readings are incorrect.
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