CONE-BEARING 2B3184 - Caterpillar

System Operation Description:Use this procedure to troubleshoot any suspect problems with the circuits for the power take-off controls (PTO). The PTO controls provide an alternative method of controlling the desired engine speed.The Electronic Control Module (ECM) provides the PTO speed control function. The PTO speed control function requires the following inputs:
PTO switches
The "PTO Mode" parameterThe PTO switches enable the PTO speed control function and the PTO switches control the desired engine speed.The "PTO Mode" parameter determines the mode of operation. There are two modes of operation: "Ramp Up/Ramp Down" and "Enable". The default mode of operation is "Ramp Up/Ramp Down". Use Caterpillar Electronic Technician (ET) in order to change the value of the parameter."Ramp Up/Ramp Down" ModeThis mode uses three inputs. The inputs are provided by two switches. Refer to Illustration 1 for a schematic of the circuit. Refer to Table 1 for the "Speed Demand Status" for the various switch positions.
Illustration 1 g01823358
Schematic for the PTO inputs for the "Ramp Up/Ramp Down" mode of operation
Table 1
Switch Status    Speed Demand Status    
PTO Enable    PTO Ramp Up    PTO Ramp Down    
Open     Any     Any     Set to the valid engine speed.    
Close     Open     Open     Remain at current desired engine speed.    
Close     Open     Close     Ramp down    
Close     Close     Open     Ramp up    
Close     Close     Close     Invalid latch speed    Placing the PTO Enable switch to the "Enable" position transfers the control of the desired engine speed to the PTO speed control function. The "PTO Ramp Up/Ramp Down Switch" controls the desired engine speed.The "PTO Ramp Up/Ramp Down Switch" is spring loaded to the normally open position. When the switch is held in the "Ramp Up" position, the desired engine speed can be increased up to ten percent above the valid engine speed. When the switch is released, the desired engine speed maintains the set speed.When the "PTO Ramp Up/Ramp Down Switch" is held in the "Ramp Down" position, the desired engine speed can be decreased up to ten percent below the valid engine speed. When the switch is released, the desired engine speed maintains the set speed.If the "PTO Ramp Up" and "PTO Ramp Down" inputs are connected to the −Battery at the same time, the ECM will ignore the inputs. The desired engine speed will not change.If the "PTO Enable Switch" is opened at any speed, the engine will immediately revert to the valid engine speed.Test Step 1. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the engine ECM.
Turn the keyswitch to the OFF position.
Illustration 2 g01167488
ECM connectors (typical example) (1) J1/P1 ECM connectors
Thoroughly inspect connectors (1) and (2). Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 3 g01857994
P1 terminals