850055A 2 Mercury THERMOSTAT KIT (55/60)

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) , (2) , and (3) . Also, thoroughly inspect the electrical condition and the mechanical condition of speed control device (4) . Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 4 g01414564
Terminal locations at the P1 ECM connector that are associated with the speed control (P1-36) Desired speed (4-20 mA) (P1-37) Return
Illustration 5 g01414576
Terminal locations at the P5 ECM connector that are associated with the speed control (P5-20) Desired speed (4-20 mA) (P5-21) Return
Illustration 6 g01414586
Terminal locations at the P10 connector that are associated with the speed control (P10-E) Desired speed (4-20 mA) (P10-J) Return
Perform a 45 N (10 lb) pull test on each of the wires in the circuit for the speed control.
Check the torque of the allen head screws for each of the ECM connectors and of the customer connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points from the terminal box to the advisor monitor display.Expected Result:All connectors, pins, and sockets are connected properly. The connectors and the wiring do not have corrosion, abrasion, or pinch points.Results:
OK - The components are in good condition with proper connections. Proceed to Test Step 2.
Not OK - The components are not in good condition and/or at least one connection is improper.Repair: Perform the necessary repairs and/or replace parts, if necessary.STOPTest Step 2. Check for Active Diagnostic Codes
Connect Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".
Restore the electrical power to the engine. Turn the engine control to the STOP position.
While you adjust the speed control from the minimum speed to the maximum speed, monitor the active and logged diagnostic codes on Cat® ET. Wait at least 30 seconds in order for diagnostic codes to become active. Look for the following active diagnostic codes:
524-3 Desired Engine Speed Sensor : Voltage Above Normal
524-4 Desired Engine Speed Sensor : Voltage Below Normal
Set the engine control to the OFF/RESET position. Remove the electrical power from the engine.Expected Result:None of the above diagnostic codes became active during the test.Results:
OK - No diagnostic codes were activated.Repair: The output for the speed control appears to be OK. The initial diagnostic code may have been caused by a poor electrical connection. If an intermittent electrical problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect", for information that is related to troubleshooting intermittent electrical problems.STOP
Active 524-3 Code - A 524-3 diagnostic code became active while you adjusted the speed control. The ECM has detected an excessive amperage in the circuit for the speed control. Proceed to Test Step 3.
Active 524-4 Code - A 524-4 diagnostic code