HUB 3P0180 - Caterpillar

System Operation Description:The load sharing module provides a throttle signal to the engine's Electronic Control Module (ECM). The output for rated speed is a pulse width modulated signal (PWM) at a constant frequency. The speed signal varies with the position of the speed adjust potentiometer. The output signal is referred to as a duty cycle or as a PWM signal. The output signal is expressed as a percentage between 0 and 100 percent for the speed adjust.Note: Desired speed can be adjusted from 1141 to 1621 rpm over the range of the PWM signal for a 50 Hz application. For a 60 Hz application, the desired speed can be adjusted from 1369 to 1945 rpm over the range of the PWM signal.The ECM calculates the desired engine rpm from the throttle signal and the droop signal. The throttle signal is valid when the duty cycle is in the range of 5 to 95 percent. If the ECM determines that the throttle signal is invalid, the engine rpm will be set to the programmed low idle.
Illustration 1 g01207558
Schematic for the speed control circuit (typical example)
Test Step 1. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the ECM.
Illustration 2 g01167488
Location of the J1/P1 ECM connectors (typical engine view)
(1) J1/P1 ECM connectors
Illustration 3 g01207581
Location of the engine interface connector (typical engine view)
(2) Engine interface connector
Thoroughly inspect connectors (1) and (2). Also, thoroughly inspect all of the other connectors that are in the circuit. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 4 g01207582
Terminal locations at the P1 ECM connector
(P1-5) Digital return
(P1-66) Throttle signal
Illustration 5 g01207583
Terminal locations at the engine interface connector
(15) Digital return
(21) Throttle signal
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector and the engine interface connector that are associated with the circuit.
Check the allen head screw on each ECM connector and the engine interface connector for the proper torque. refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points. Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion or of pinch points.Results:
OK - The connectors and wiring appear to be OK. Proceed to Test Step 2.
Not OK - The connectors and/or wiring are not OK.Repair: Repair the connectors or wiring and/or replace the connectors or wiring.Repair CompleteTest Step 2. Check the Supply Voltage to the Speed Control
Restore electrical power to the ECM.
Measure the voltage between terminal 15 (+Battery) and terminal 16 (−Battery) on the speed control.
Remove electrical power from the ECM. Expected Result:The voltage is 24 3 VDC.Results:
OK - The voltage is 24 3 VDC. The voltage supply to the speed control is correct. Proceed to Test Step 3.
Not OK - The voltage is not 24 3 VDC.Repair: There is a problem in a harness or a connector between the batteries and the speed control. The