924K, 926M, 930K, 930M, 938K and 938M Wheel Loaders Caterpillar

Sensor Signal (PWM) - Test

Usage:

930K FRK

Machine ECM

The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the PWM sensors of the machine.

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Table 1
Machine ECM (MID 39)
DTC	Code Description	System Response
350-3	Lift Linkage Position Sensor: Voltage Above Normal	The float function will not work properly. The lift and tilt kickout function will not work properly. Snubbing features will not work properly. Some implement functions may operate at a reduced speed.
350-4	Lift Linkage Position Sensor: Voltage Below Normal	The float function will not work properly. The left and tilt kickout function will not work properly. Snubbing features will not work properly. Some implement functions may operate at a reduced speed.
350-8	Lift Linkage Position Sensor: Abnormal Frequency, Pulse Width, or Period	The float function will not work properly. The left and tilt kickout function will not work properly. Snubbing features will not work properly. Some implement functions may operate at a reduced speed.
350-10	Lift Linkage Position Sensor: Abnormal Rate of Change	The parallel lift feature will not function.
350-13	Lift Linkage Position Sensor: Calibration Required	Snubbing features will not work properly. Some implement functions may operate at a reduced speed.
351-3	Tilt Linkage Position Sensor: Voltage Above Normal	The tilt kickout function will not work properly. Snubbing features will not work properly. Some implement functions may operate at a reduced speed.
351-4	Tilt Linkage Position Sensor: Voltage Below Normal	The tilt kickout function will not work properly. Snubbing features will not work properly. Some implement functions may operate at a reduced speed.
351-8	Tilt Linkage Position Sensor: Abnormal Frequency, Pulse Width, or Period	The tilt kickout function will not work properly. Snubbing features will not work properly. Some implement functions may operate at a reduced speed.
351-10	Tilt Linkage Position Sensor: Abnormal Rate of Change	The parallel lift feature will not function.
351-13	Tilt Linkage Position Sensor: Calibration Required	Snubbing features will not work properly. Some implement functions may operate at a reduced speed.
352-3	Lift Lever Sensor: Voltage Above Normal	All lift functions will be inoperable.
352-4	Lift Lever Sensor: Voltage Below Normal	All lift functions will be inoperable.
352-8	Lift Lever Sensor: Abnormal Frequency, Pulse Width, or Period	All lift functions will be inoperable or intermittent.
353-3	Tilt Lever Sensor: Voltage Above Normal	All tilt functions will be inoperable.
353-4	Tilt Lever Sensor: Voltage Below Normal	All tilt functions will be inoperable.
353-8	Tilt Lever Sensor: Abnormal Frequency, Pulse Width, or Period	All tilt functions will be inoperable or intermittent.
364-3	Lift Cylinder Head Pressure Sensor: Voltage Above Normal	The Payload Control System (PCS) feature is disabled.
364-4	Lift Cylinder Head Pressure Sensor: Voltage Below Normal	The Payload Control System (PCS) feature is disabled.
364-8	Lift Cylinder Head Pressure Sensor: Abnormal Frequency, Pulse	The Payload Control System (PCS) feature is disabled.
487-3	Third Lever Position Sensor: Voltage Above Normal	The work tool assigned to the lever will not work properly.
487-4	Third Lever Position Sensor: Voltage Below Normal	The work tool assigned to the lever will not work properly.
487-8	Third Lever Position Sensor: Abnormal Frequency, Pulse Width, or Period	The work tool assigned to the lever will not work properly.
488-3	Fourth Lever Position Sensor: Voltage Above Normal	The work tool assigned to the lever will not work properly.
488-4	Fourth Lever Position Sensor: Voltage Below Normal	The work tool assigned to the lever will not work properly.
488-8	Fourth Lever Position Sensor: Abnormal Frequency, Pulse Width, or Period	The work tool assigned to the lever will not work properly.
769-3	Lift Cylinder Rod Pressure Sensor: Voltage Above Normal	The Payload Control System (PCS) feature is disabled.
769-4	Lift Cylinder Rod Pressure Sensor: Voltage Below Normal	The Payload Control System (PCS) feature is disabled.
769-8	Lift Cylinder Rod Pressure Sensor: Abnormal Frequency, Pulse	The Payload Control System (PCS) feature is disabled.
2305-3	Brake/Decelerator Pedal Position Sensor: Voltage Above Normal	The pedal inching position is held at the last known position. If diagnostic code is present at KEY ON, the drivetrain defaults to a depressed pedal condition.
2305-4	Brake/Decelerator Pedal Position Sensor: Voltage Below Normal	The pedal inching position is held at the last known position. If diagnostic code is present at KEY ON, the drivetrain defaults to a depressed pedal condition.
2305-8	Brake/Decelerator Pedal Position Sensor: Abnormal Frequency, Pulse Width, or Period	The pedal inching position is held at the last known position. If diagnostic code is present at KEY ON, the drivetrain defaults to a depressed pedal condition.
2305-13	Brake/Decelerator Pedal Position Sensor: Calibration Required	If diagnostic is present, default duty cycles are used to determine pedal position.
2470-3	Primary Steering Pressure Sensor: Voltage Above Normal	Shut down the machine. The ECM will not know secondary steering pressure. Secondary system will stay on or off depending on what state the ECM was in before the fault occurred.
2470-4	Primary Steering Pressure Sensor: Voltage Below Normal	Shut down the machine. The ECM will not know the primary steering pressure. Secondary system will stay on or off depending on what state the ECM was in before the fault occurred.
2470-8	Primary Steering Pressure Sensor: Abnormal Frequency, Pulse Width, or Period	Shut down the machine. The ECM will not know the primary steering pressure. Secondary system will stay on or off depending on what state the ECM was in before the fault occurred.
2976-3	Parking Brake Oil Pressure Sensor: Voltage Above Normal	The parking brake state is not known. Lower the bucket to the ground and chock all wheels before the operator leaves the cab.
2976-4	Parking Brake Oil Pressure Sensor: Voltage Below Normal	The parking brake state is not known. Lower the bucket to the ground and chock all wheels before the operator leaves the cab.
2976-8	Parking Brake Oil Pressure Sensor: Abnormal Frequency, Pulse Width, or Period	The parking brake state is not known. Lower the bucket to the ground and chock all wheels before the operator leaves the cab.
2987-3	Brake Charge Pressure Sensor #1: Voltage Above Normal	Move the machine to a safe location and cease operation. When the diagnostic code is active, the parking brake indicator will not illuminate when the switch is pressed.
2987-4	Brake Charge Pressure Sensor #1: Voltage Below Normal	Move the machine to a safe location and cease operation. When the diagnostic code is active, the parking brake indicator will not illuminate when the switch is pressed.
2987-8	Brake Charge Pressure Sensor #1: Abnormal Frequency, Pulse Width, or Period	Move the machine to a safe location and cease operation. When the diagnostic code is active, the parking brake indicator will not illuminate when the switch is pressed.
2993-3	Direction Selector Position Sensor #1: Voltage Above Normal	If a DTC 2993 and DTC 2994 are active at the same time, the machine will hold the last known position of the direction selector.
2993-4	Direction Selector Position Sensor #1: Voltage Below Normal	If a DTC 2993 and DTC 2994 are active at the same time, the machine will hold the last known position of the direction selector.
2993-8	Direction Selector Position Sensor #1: Abnormal Frequency, Pulse Width, or Period	If a DTC 2993 and DTC 2994 are active at the same time, the machine will hold the last known position of the direction selector
2994-3	Direction Selector Position Sensor #2: Voltage Above Normal	If a DTC 2993 and DTC 2994 are active at the same time, the machine will hold the last known position of the direction selector.
2994-4	Direction Selector Position Sensor #2: Voltage Below Normal	If a DTC 2993 and DTC 2994 are active at the same time, the machine will hold the last known position of the direction selector.
2994-8	Direction Selector Position Sensor #2: Abnormal Frequency, Pulse Width, or Period	If a DTC 2993 and DTC 2994 are active at the same time, the machine will hold the last known position of the direction selector.
3527-12	Direction Selector: Bad Device or Component	Machine will hold last known position
3561-3	Drive Circuit Forward Pressure Sensor: Voltage Above Normal	Electronic pressure limiting will be disabled in the forward direction. Rimpull limiting feature will be disabled, and the hydrostatic torque limiting will operate at a reduced level.
3561-4	Drive Circuit Forward Pressure Sensor: Voltage Below Normal	Electronic pressure limiting will be disabled in the forward direction. Rimpull limiting feature will be disabled, and the hydrostatic torque limiting will operate at a reduced level.
3561-8	Drive Circuit Forward Pressure Sensor: Abnormal Frequency, Pulse Width, or Period	Electronic pressure limiting will be disabled in the forward direction. Rimpull limiting feature will be disabled, and the hydrostatic torque limiting will operate at a reduced level.
3561-13	Drive Circuit Forward Pressure Sensor: Out of Calibration	Electronic pressure limiting will use default pressure limit value.
3562-3	Drive Circuit Reverse Pressure Sensor: Voltage Above Normal	Electronic pressure limiting will be disabled in the reverse direction. Rimpull limiting feature will be disabled, and the hydrostatic torque limiting will operate at a reduced level.
3562-4	Drive Circuit Reverse Pressure Sensor: Voltage Below Normal	Electronic pressure limiting will be disabled in the reverse direction. Rimpull limiting feature will be disabled, and the hydrostatic torque limiting will operate at a reduced level.
3562-8	Drive Circuit Reverse Pressure Sensor: Abnormal Frequency, Pulse Width, or Period	Electronic pressure limiting will be disabled in the reverse direction. Rimpull limiting feature will be disabled, and the hydrostatic torque limiting will operate at a reduced level.
3654-3	Implement Pump Pressure Sensor: Voltage Above Normal	Implement Torque Load Control (ITLC) will be disabled and the machine will run at a reduced performance level.
3654-4	Implement Pump Pressure Sensor: Voltage Below Normal	Implement Torque Load Control (ITLC) will be disabled and the machine will run at a reduced performance level.
3654-8	Implement Pump Pressure Sensor: Abnormal Frequency, Pulse Width, or Period	Implement Torque Load Control (ITLC) will be disabled and the machine will run at a reduced performance level.

Possible causes for an FMI 3 diagnostic code are:

The sensor has failed.
The sensor supply or the ground circuit in the machine harness is open.
The signal circuit in the machine harness is shorted to the +battery.
The signal circuit in the machine harness is open or the sensor is disconnected.
The system has been activated in Cat ET when there is no component installed on the machine.
The ECM has failed. A failure of the ECM is unlikely.

Possible causes for an FMI 4 diagnostic code are:

The sensor has failed.
The signal circuit in the machine harness is shorted to ground.
The ECM has failed. A failure of the ECM is unlikely.

Possible causes for an FMI 8 diagnostic code are:

The sensor has failed.
Intermittent connections or poor connections.

Possible causes for an FMI 10 diagnostic code are:

An external force caused the lift or tilt cylinders to move at an abnormally fast speed.
The sensor has failed.
Poor connections or intermittent connections in the speed sensor circuit.
Internal mechanical problems.
The ECM has failed. This option is unlikely.

Possible causes for an FMI 12 diagnostic code are:

The sensor has failed.

Possible causes for an FMI 13 diagnostic code are:

The sensor requires calibration.
The sensor requires adjustment.
The ECM has been flashed with new software, resulting in a request for calibration.
The ECM has failed. A failure of the ECM is unlikely.

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Illustration 1	g03751297
Schematic of the PWM connections

Note: The diagram above is a simplified schematic of the connections for the PWM connections. The schematic is electrically correct. However, not all the possible harness connectors are shown. Refer to the latest revision of the electrical schematic for the specific machine being serviced for the complete schematic.

Diagnostic Trouble Code Procedure

Note: Prior to beginning this procedure, inspect the harness connectors that are involved in this circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure, and in good condition. Check the wiring for pinch points or abrasions. Look for and repair areas that indicate wires are exposed. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing a troubleshooting procedure.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Identify Active DTC Code Associated With Sensor Circuit	Codes present.	FMI 3 diagnostic code, proceed to Test Step 3. FMI 4 diagnostic code, proceed to Test Step 6. FMI 8 & FMI 10 diagnostic code, proceed to Test Step 8. FMI 13 diagnostic code, proceed to Test Step 11. FMI 12 diagnostic code, proceed to Test Step 14.
Begin Process For FMI 3 Troubleshooting HERE
3. Check The Supply Voltage at the Sensor A. Turn key start switch and disconnect switch ON. B. Disconnect the machine harness from sensor. C. Refer to the schematic to determine the voltage source for the suspected faulty sensor. D. Measure voltage between supply and ground contacts at the machine harness connector for the sensor.	Voltage is 8.0 VDC ± 0.5 VDC or 10.0 VDC ± 0.5 VDC or in the case of implement lift and implement tilt sensors, battery voltage - 0.5 VDC.	OK - The voltage reading is correct for the suspected faulty sensor. Proceed to Test Step 4. NOT OK- The voltage is NOT correct for the circuit. Repair - Refer to the diagnostic code procedure in this manual for troubleshooting of the power supply. After the power supply procedure is performed, verify the status of the sensor diagnostic code before proceeding. STOP
4. Check For An Open In The Sensor Circuit A. The sensor remains disconnected from the machine harness. B. Turn the key start switch and the disconnect switch OFF. C. At the harness connector for the sensor, place a jumper wire between the signal contact and the ground contact. D. Disconnect J1 and J2 harness connectors from the ECM. E. At machine harness connector for ECM, measure the resistance from the signal contact to return contact for the sensor. F. Gently pull on the wires and move the wires in a circular motion at ECM connector and observe the resistance readings. Repeat the process for the sensor connector.	The resistance is less than 5 Ω always during the manipulation of the harness.	OK - The resistance is less than 5 Ω. The signal circuit and the ground circuits of the sensor are not open in the machine harness. Proceed to Test Step 5. NOT OK - Resistance reading for the signal circuit or the return circuit is greater than 5 Ω. Repair: Check the signal circuit or the ground circuit for opens or bad connections. Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. STOP
5. Check Signal Circuit For A Short To +Battery A. The Sensor and the ECM are disconnected from the harness. B. Remove the jumper wire installed in the previous step. C. Turn the disconnect switch and the key start switch OFF. D. Measure the resistance between the signal wire and all other wires used in the J1 and J2 harness connectors.	Resistance greater than 5K Ω for all readings.	OK - The resistance is greater than 5K Ω. The harness circuit is correct. Proceed to Test Step 13. NOT OK- The resistance less than 5 Ω. Repair: A short exists in the harness between the +battery and signal circuit. Repair or replace the machine harness. Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. STOP
Begin Process For FMI 4 Troubleshooting HERE
6. Check The Sensor A. With FMI 4 active, disconnect the sensor from the machine harness. B. Observe Cat ET or the operator monitor for code change as the sensor is disconnected and connected to harness.	Code changes from FMI 4 to FMI 3.	OK - The diagnostic changed to FMI 3 when the sensor was disconnected. Repair: Replace the sensor. STOP NOT OK - The FMI 4 diagnostic code remains active when sensor is disconnected. The sensor not the cause of the problem. Proceed to Test Step 7.
7. Check The Signal Circuit For A Short To Ground A. Turn the key start switch and the disconnect switch OFF. B. Disconnect the J1 harness and J2 connectors from the ECM. C. Measure the resistance between the signal contact for sensor and all other contacts used in the J1 and J2 harness connectors.	The resistance is greater than 5K Ω.	OK - The resistance is greater than 5K Ω. The harness circuit is correct. Proceed to Test Step 13. NOT OK - The resistance is less than 5 Ω. A short circuit exists between frame ground and the signal circuit. Repair: Repair or replace the machine harness. Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. STOP
Begin Process For FMI 8 & FMI 10 Troubleshooting HERE
8. Check For An Open In The Sensor Circuit A. The sensor remains disconnected from the machine harness. B. Turn the key start switch and the disconnect switch OFF. C. At the harness connector for the sensor, place a jumper wire between the signal contact and the ground contact. D. Disconnect J1 and J2 harness connectors from the ECM. E. At machine harness connector for ECM, measure the resistance from the signal contact to return contact for the sensor. F. Gently pull on the wires and move the wires in a circular motion at ECM connector and observe the resistance readings. Repeat the process for the sensor connector.	The resistance is less than 5 Ω always during the manipulation of the harness.	OK - The resistance is less than 5 Ω. The signal circuit and the ground circuits of the sensor are not open in the machine harness. Proceed to Test Step 9. NOT OK - Resistance reading for the signal circuit or the return circuit is greater than 5 Ω. Repair: Check the signal circuit or the ground circuit for opens or bad connections. Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. STOP
9. Check The Signal Circuit For Shorts A. Turn key start switch and disconnect switch OFF. B. Disconnect J1 and J2 harness connectors from the Machine ECM. Remove the jumper wire installed in the previous step. C. Measure resistance between signal contact for sensor and all other contacts used in the J1 and J2 harness connectors.	Reading is greater than 5K Ω.	OK - Measurement is greater than 5K Ω. Proceed to Test Step 10. NOT OK - Measurement is less than 5 Ω. The signal circuit in the harness is shorted to ground. Repair: Repair or replace the machine harness. Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. STOP
10. Check The Sensor A. With FMI 8 active, disconnect the sensor from the machine harness. B. Observe Cat ET or the operator monitor for code change as the sensor is disconnected and connected to harness.	Code changes from FMI 8 to FMI 3.	OK - The diagnostic changed to FMI 3 when the sensor was disconnected. Repair: Replace the sensor. STOP NOT OK - The FMI 8 diagnostic code remains active when sensor is disconnected. The sensor not the cause of the problem. Proceed to Test Step 13.
Begin Process For FMI 13 Troubleshooting HERE
11. Check for possible companion codes. A. Turn the key start switch and the disconnect switch ON. B. Open the list of diagnostic code lists shown in the Cat ET system. The list can also be found by navigating the operator monitor.	No other codes related to the faulty sensor are identified.	OK - No diagnostic codes related to the faulty sensor are identified. Proceed to Test Step 12. NOT OK - More than one diagnostic code is active or logged related to the suspect CID code. Repair: Before starting calibration, troubleshoot all CID codes related to the suspect sensor. After troubleshooting is complete, confirm presence of FMI 13 code. Proceed to Test Step 13.
12. Perform Calibration. A. Use Cat ET to calibrate the suspect sensor.	Calibration successful.	OK - Calibration completed. Proceed to Test Step 13. NOT OK - A second attempt should be made to complete the calibration. Check the Cat ET program for any information concerning the failure to complete calibration. Proceed to Test Step 13.
13. Check If The Diagnostic Code Remains. A. Turn the key start switch and the disconnect switch ON. B. Clear all diagnostic codes. C. Operate the machine. D. Stop machine and engage the safety lock lever. E. Check if the diagnostic code for the sensor is active.	The code for the sensor is NO longer present.	OK - The diagnostic code does not exist now. The initial diagnostic code may have been caused by a poor electrical connection or a short at one of the harness connections. Resume machine operation. STOP NOT OK - The diagnostic trouble code has not been corrected. Repair: Recheck the circuit and perform this procedure again. If the diagnostic code is still active, the Machine ECM may require replacement. Prior to replacing the ECM, always contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. Follow the procedure in Testing and Adjusting, "ECM - Replace" to replace the ECM. STOP
Begin Process For FMI 12 Troubleshooting HERE
14. Check The PWM Duty Cycle A. Check the PWM duty cycle at each switch position: FNR PWM 1 signal circuit between contact 8 (wire E946-OR(Orange)) and contact 12 (wire J764-BR(Brown)). FNR PWM 2 signal circuit between contact 9 (wire E947-WH(White)) and contact 12 (wire J764-BR(Brown)).	All Duty Cycles are within 5% of one another.	OK -All Duty Cycles are within 5% of one another. Proceed to Test Step 15. NOT OK - The most likely cause is a failed switch, however, proceed to Test Step 13 to check the switch with the machine harness disconnected.
15. Check the Status Of The Diagnostic Code A. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the switch circuit. B. Reconnect all harness connectors. Make sure that the connectors are fully seated and the clips for each connector are fastened. Turn the disconnect switch and the key start switch to the ON position. Determine if the CID 3527 FMI 12 diagnostic code is active.	The CID 3527 FMI 12 diagnostic code is not active.	OK - The CID 3527 FMI 12 diagnostic code is not active. The diagnostic code does not exist now. The initial diagnostic code was probably caused by a poor connection or a short at one of the connectors that was disconnected and reconnected. Resume normal operation. NOT OK - The CID 3527 FMI 12 diagnostic code is active. The problem has not been corrected. REPAIR - If the problem has not been corrected, use Caterpillar Electronic Technician to perform a "Wiggle Test" on the switch circuit. The wiggle test can detect momentary or intermittent shorts or opens in the machine wiring harness. If the cause of the problem is not found, perform this procedure again. If no problems were found during troubleshooting, the ECM could have activated the diagnostic code in error. Prior to replacing an ECM, always contact the Technical Communicator of your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If troubleshooting steps determine that the ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".