PULLEY GP-FAN 3851339 - Caterpillar

Test Step 1. CHECK THE SYSTEM VOLTAGE OF THE ECM
Turn the disconnect switch and the key start switch to the OFF position.
At the J1 harness connector for the Brake ECM, insert a 7X-1710 Multimeter Probe along the contact of the system power J1-31 (wire 176-RD(Red)). Use the other multimeter probe to make contact to frame ground.
Turn the disconnect switch to the ON position.
Start the engine and run the engine at half throttle.
Measure the voltage between contact J1-31 (wire 176-RD(Red)) and frame ground.
Observe the resistance measurement of the multimeter while wiggling the machine harness for the Brake ECM. Gently pull on the wires and manipulate the wires.
At the J1 harness connector for the Brake ECM, insert the 7X-1710 Multimeter Probe that was used for the frame ground contact along the system power supply negative battery contact J1-13 (wire A252-BK(Black)).
Measure the voltage between contact J1-31 (wire 176-RD(Red)) and contact J1-13 (wire A252-BK(Black)).
Observe the resistance measurement of the multimeter while wiggling the machine harness connectors for the Brake ECM. Gently pull on the wires and manipulate the wires.Expected Result:Both voltage measurements are approximately the same and are in the range of 18 VDC to 32 VDC always during the manipulation of the harness and the connectors.Results:
OK - Each voltage measurement is approximately the same. Each voltage measurement is in the range of 18 VDC to 32 VDC. The system voltage is correct always during the manipulation of the harness and connectors. Proceed to Test Step 6.
NOT OK - Each voltage measurement is approximately the same, however the measurements are not stable. The voltage measurements are showing a large amount of variation. The manipulation of the machine harness and connectors does not affect the measurement. Proceed to Test Step 4.
NOT OK - The measurement from the positive battery contact to frame ground is stable and is in the range of 18 VDC to 32 VDC, however, the measurement between the ECM positive battery contact and the ECM negative battery contact is not stable in the correct range at alltimes. Proceed to Test Step 2.Test Step 2. CHECK THE GROUND CIRCUITS
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness J1 connector from the ECM.
At the J1 harness connector for the ECM, measure the resistance between each of the four negative battery contacts and frame ground. The contacts for the negative battery connections are illustrated in the connection diagram at the beginning of this procedure.Expected Result:Each resistance measurement is less than 5 ohms.Results:
OK - Each resistance measurement is less than 5 ohms. The ground circuit is correct. Reconnect the J1 machine harness connector to the ECM before proceeding to the next test step. Proceed to Test Step 3.
NOT OK - One or more of the resistance measurements are greater than 5 ohms. There is an open circuit or a poor connection in the ground circuit.Repair: The open or the possible poor connection is in the ground circuit for the ECM (wire A252-BK(Black)) in the machine