PAD AS 2137322 - Caterpillar

System Operation Description:Use this procedure to troubleshoot a suspected problem with the circuit that is for the speed control. Use this procedure if one of the diagnostic codes in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table    
Description    Conditions which Generate this Code    System Response    
524-3 Desired Engine Speed Sensor : Voltage Above Normal     The Electronic Control Module (ECM) has detected an excessive amperage in the circuit for the desired speed signal. The amperage has exceeded 22 mA for more than 5 seconds.     The code is logged.
The alarm output is activated.    
524-4 Desired Engine Speed Sensor : Voltage Below Normal     The ECM has detected a low amperage for the desired speed signal. The amperage is less than 2 mA for more than 5 seconds.    Note: For this troubleshooting procedure, the "Desired Speed Input" configuration parameter must be set to "4-20 mA Input" in the "Service/Configuration" screen of the Caterpillar Electronic Technician (ET). Do not select "PWM". The master ECM cannot be configured to accept a Pulse Width Modulated signal (PWM) for speed control for the engine.The selection of the "4-20 mA Input" setting requires a 4 to 20 mA signal for regulation of the desired engine speed. Do not use this procedure if the "Desired Speed Input" is set to "0-5 VDC Input".When the desired speed input is correspondingly configured, the master ECM controls the engine speed according to the 4 to 20 mA current.The value of the current corresponds to a range of desired engine speeds between minimum high idle and maximum high idle. The "Minimum Engine High Idle Speed" and the "Maximum Engine High Idle Speed" are set with the "Service/Configuration" screen of Cat ET. For more information, refer to Troubleshooting, "Configuration Parameters".When the idle/rated speed switch is in the RATED position, a current value of 4.0 mA corresponds to the programmed "Minimum Engine High Idle Speed". A current value of 20.0 mA corresponds to "Maximum Engine High Idle Speed". Current values within this range will vary the desired engine speed in a linear fashion. The values will vary between "Minimum Engine High Idle Speed" and "Maximum Engine High Idle Speed".The most likely causes of a diagnostic code for this circuit are a poor connection or a problem in a wiring harness. The next likely cause is a problem with a component. The least likely cause is a problem with the master ECM.
Illustration 1 g01586196
Schematic of the circuit for the 4 to 20 mA desired speed inputTest Step 1. Inspect the Electrical Connectors and the Wiring
Set the engine control to the OFF/RESET position. Remove the electrical power from the engine.
Illustration 2 g01414551
Location of the connectors at the terminal box that are for the speed control (1) J1/P1 ECM connectors at the master ECM (2) J5/P5 customer connectors (3) J10/P10 connectors for the advisor monitor display
Illustration 3 g01461289
Location of the potentiometer for the desired speed at the engine display panel (4) Speed potentiometer
Thoroughly inspect the condition of connectors (1)