PISTON 8J6076 - Caterpillar

Illustration 1 g00442023
System Schematic For Starting Motor Relay (SMR)
Illustration 2 g00442025
Junction Box For Earlier Generators - Cover RemovedLocated on exterior of generator terminal box. (1) Starting motor magnetic switch
Illustration 3 g00737977
Junction Box For Later Generators - Cover RemovedLocated on exterior of generator terminal box. (1) Starting motor magnetic switchTwo starting motor magnetic switches (SMMS) are used in dual starting motor systems, one for each starting motor.Test Procedure
From beneath the control panel, disconnect DC connector number 2 from the control panel. DC connector number 2 is the left most connector when viewed from the front panel. From beneath the control panel use the 7X-1710 Cable Probes to measure the resistance between connector contact 6 (SMMS) and connector contact 11 (B-). The resistance should measure the following values.
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 going from the pinion solenoid to the starting motor. Do this on both starting motors of a dual starting motor system.
Inside the junction box, at the SMMS, prepare to connect a DC voltmeter. The positive lead connects to wire 24 and the negative lead connects to wire 25. (If a second magnetic switch is tested in a dual starting motor system, then connect the negative lead to wire 26.)Note: The jumper wire of Step 4 4 energizes the starting motor magnetic switch.The jumper wire can remain connected for only ten seconds.
In the junction box, at the SMMS, temporarily connect a jumper wire from terminal 1 (B+) to terminal 4. Disconnect this wire immediately after the voltage is measured (no more than 10 seconds). The correct measurement changes from approximately 24 DCV to approximately 2 DCV.If voltage is greater than 2.0 DCV, then replace the magnetic switch. If the switch passes the requirements of Step 1 and Step 4, it is functioning correctly. Reconnect the wires and cables that were removed in this procedure.