NUT 1B4206 - Caterpillar

Illustration 1 g00531356
System Schematic For Starting Motor Relay (SMR)
Illustration 2 g00583676
Junction Box Without The Cover(The junction box is located on the side of the generator terminal box.) (1) Starting Motor Magnetic Switch (SMMS).Two starting motor magnetic switches (SMMS) are used in a system with two starting motors. One switch is used for each starting motor.Test Procedure
From beneath the control panel, disconnect DC connector 2 from the control panel. DC connector 2 is the left most connector when viewed from the front panel. From beneath the control panel use the 7X-1710 Multimeter Probes in order to measure the resistance between connector contact 6 (SMMS) and connector contact 11 ("B-"). The resistance should measure the following value.
26 to 33 ohms for single starting motor systems
13 to 17 ohms for dual starting motor systemsIf the resistance is NOT correct, replace the defective magnetic switch. If the resistance is correct, proceed to Step 2.
Disconnect the cable that is going from the pinion solenoid to the starting motor. Do this procedure on both starting motors of a dual starting system.
Connect a DC voltmeter. Connect the positive cable to terminal TS1-24 and the negative cable to TS1-25 in the generator housing. If the second magnetic switch is tested in a dual starting motor system, then connect the negative cable to terminal TS1-26.Note: The jumper wire of Step 4 can remain connected for only ten seconds.
Temporarily connect wire 4 to the battery positive terminal ("B+"). Disconnect this wire immediately after the voltage is measured. Do NOT leave the wire connected more than ten seconds. The correct measurement changes from approximately 24 DCV to approximately 2 DCV.If the voltage is greater than 2.0 DCV, then replace the magnetic switch. If the switch passes the requirements of Step 1 and Step 4, the switch is functioning correctly. Reconnect the wires and cables that were removed in this procedure.