PISTON 6B3301 - Caterpillar

Test Step 1. CHECK THE CIRCUIT FOR AN OPEN
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connectors J1 and J2 from the Implement ECM and from the Transmission/Chassis ECM.
Obtain a spare length of wire that will reach from the connectors for the Implement ECM to the connectors for the Transmission/Chassis ECM .
At the Implement ECM connector J2 connect one end of the spare wire to the request circuit contact J2-19 (wire U753-BR(Brown)).
At the Transmission/Chassis ECM connector J2, measure the resistance between the other end of the spare wire and the request circuit contact J2-25 (wire U753-BR(Brown). Expected Result:The resistance measurement is less than 5 ohms.Results:
OK - The resistance measurement is less than 5 ohms. The resistance measurement is not indicating that the secondary steering request circuit is open in the machine harness. Proceed to Test Step 2.
NOT OK - The resistance measurement is greater than 5 ohms. There is an open or a bad connection in the circuit for the secondary steering request.Repair: A resistance measurement that is greater than 5000 ohms could indicate that a wire is not connected or that a wire is open. A resistance measurement that is greater 5 ohms but less than 5000 ohms could indicate that one of the connection points in the circuit is not an open connection but not a good connection.A poor connection can cause the problem. A connector may be loose, dirty or corroded. Inspect the connectors that are in the circuit. Ensure that all connectors are clean, that all connectors are tight and that all connectors are in good condition.The open or the possible bad connection is in wire U753-BR(Brown). Refer to the complete Electrical System Schematic of the machine . Check all of the connectors that are in the circuit. Ensure that all connections are clean, that all connections are secure and that all connections are in good condition. Repair the machine harness or replace the machine harness.STOPTest Step 2. CHECK THE CIRCUIT FOR A SHORTThe key start switch and the disconnect switch remain in the OFF position. The machine harness connectors for both ECM modules remain disconnected.
Remove the spare wire that was used in the last test step.
At the J2 machine harness connector for the Transmission/Chassis ECM, measure the resistance from the contact J2-25 (wire U753-BR(Brown)) to all of the other J1 and J2 contacts that are used on the connectors of the Transmission/Chassis ECM.
At the J2 machine harness connector for the Implement ECM, measure the resistance from the contact J2-19 (wire U753-BR(Brown)) to all of the other J1 and J2 contacts that are used on the connectors of the Implement ECM. Expected Result:Each resistance measurement is greater than 5000 ohms.Results:
OK - Each resistance measurement is greater than 5000 ohms. The measurement does not indicate that the request signal circuit is shorted in the machine harness. Proceed to Test Step 3.
NOT OK - One or more of the resistance measurements is less than 5000 ohms.Repair: There is