Water Delivery System and 777F WTR, 777G WTR and 785D WTR OEM Off-Highway Trucks Caterpillar

Sensor Signal (Analog, Active) - Test

Usage:

785D DMC

The WDS uses several sensors. The test procedure specific to each WDS sensor is described below.

Water Pressure Sensor Error

This diagnostic code is recorded when the WDS water pressure sensor has malfunctioned. Voltage signals of less than 0.3 VDC or greater than 5 VDC can generate this fault. Pressure signals of less than −138 kPa (−20 psi) or greater than 1380 kPa (200 psi) can also generate this fault.

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Illustration 1	g03643548

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Illustration 2	g03643559

The possible causes of this diagnostic code are listed below:

Moisture entry into the connector
Electrical harness damage
Damage to the sensor
Damaged XA2 module

Check for Moisture Entry into Connector
1. Park the machine. Turn key start switch to the OFF position.
2. Turn the machine disconnect switch to the OFF position.
3. Disconnect connector "R-C12" from the water pressure sensor.
4. Thoroughly dry both sides of the connector.
5. Inspect the pins for corrosion.
6. Reassemble the connector with a light coating of dielectric grease.
7. Check the continuity of each pin through the connector.
  Expected Results: All connections are continuous through the connector.
  Results:
  OK - All connections are continuous. Proceed to Step 2.
  Not OK - One or more of the connections did not show continuity, and the diagnostic is still present.
  Repair: Replace the pins and the connector.
Check Electrical Harness
1. Park the machine. Turn key start switch to the ON position.
2. Disconnect connector "R-C12" from the water pressure sensor.
3. Check pin "1" for 5 VDC.
4. Check pin "2" for ground.
5. Check the continuity of wire M914-WH(White) from connector "R-C12" to pin "12" of connector "RC-C1".
  Expected Result: Pin "1" has 5 VDC, pin "2" is continuous to ground, and wire M914-WH(White) is continuous.
  Results:
  OK - All pins check fine. Proceed to Step 3.
  Not OK - One or more of the pins did not check out correctly.
  Repair: Inspect the harness for damage. Repair or replace the harness if necessary.
Check Sensor
1. Park the machine. Turn key start switch to the OFF position.
2. Turn the machine disconnect switch to the OFF position.
3. Disconnect connector "R-C12" from the water pressure sensor.
4. Make sure that water tank is empty. If this action is not performed, water will spray out of the sensor port when the sensor is removed.
5. Remove the sensor from the water bar.
6. Inspect the sensor for damage or possibly a clogged pressure port in the end of the sensor.
  Expected Result: The pressure port is clean, and the sensor has no external corrosion or damage.
  Results:
  OK - The pressure port is clean, and the sensor has no external corrosion or damage. Proceed to Step 4.
  Not OK - The sensor has a clogged pressure port, visible external damage from impact, or visible corrosion.
  Repair: Replace the sensor.
Check XA2 I/O Module
1. Park the machine. Turn the key switch to the ON position.
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  Illustration 3 g03643619
2. Inspect the module. Note the color and sequence of the lights on top.
3. Power-on LED (2) is green. Status LED (1) is yellow or red. The status LED flashes red when an error has been detected.
4. Ensure that the electrical connector is seated.
5. Cycle the key power.
  Expected Result: Power-on LED (2) is solid green, and status LED (1) is flashing yellow.
  Results:
  OK - The LEDs indicate a properly operating module, and no errors are present in the system.
  Not OK - Status LED (1) flashes red, indicating a failure, or the "Rear Mount" module shows diagnostics on the WDS display.
  Repair: Replace the XA2 I/O Module.
  STOP.

Water Tank Level Sensor

This diagnostic code is recorded when the WDS tank level sensor has malfunctioned. Voltage signals of less than 0.3 VDC or greater than 5 VDC can generate this fault. Pressure signals of less than −21 kPa (−3 psi) or greater than 103 kPa (15 psi) can also generate this fault.

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Illustration 4	g03643548

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Illustration 5	g03643735

The possible causes of this diagnostic code are listed below:

Moisture entry into the connector
Electrical harness damage
Damage to the sensor
Damaged XA2 module

Check for Moisture Entry into Connector
1. Park the machine. Turn key start switch to the OFF position.
2. Turn the machine disconnect switch to the OFF position.
3. Disconnect connector "R-C15" from the tank level sensor.
4. Thoroughly dry both sides of the connector.
5. Inspect the pins for corrosion.
6. Reassemble the connector with a light coating of dielectric grease.
7. Check the continuity of each pin through the connector.
  Expected Results: All connections are continuous through the connector.
  Results:
  OK - All connections are continuous. Proceed to Step 2.
  Not OK - One or more of the connections did not show continuity, and the diagnostic is still present.
  Repair: Replace the pins and the connector.
Check Electrical Harness
1. Park the machine. Turn key start switch to the ON position.
2. Disconnect connector "R-C15" from the tank level sensor.
3. Check pin "1" for 5 VDC.
4. Check pin "2" for ground.
5. Check the continuity of wire L958-BU(Blue) from connector "R-C15" to pin "13" of connector "RC-C1".
  Expected Result: Pin "1" has 5 VDC, pin "2" is continuous to ground, and wire L958-BU(Blue) is continuous.
  Results:
  OK - All pins check fine. Proceed to Step 3.
  Not OK - One or more of the pins did not check out correctly.
  Repair: Inspect the harness for damage. Repair or replace the harness if necessary.
Check Sensor
1. Park the machine. Turn key start switch to the OFF position.
2. Turn the machine disconnect switch to the OFF position.
3. Disconnect connector "R-C15" from the tank level sensor.
4. Make sure that water tank is empty. If this action is not performed, water will spray out of the sensor port when the sensor is removed.
5. Remove the sensor from the water tank.
6. Inspect the sensor for damage or possibly a clogged pressure port in the end of the sensor.
  Expected Result: The pressure port is clean, and the sensor has no external corrosion or damage.
  Results:
  OK - The pressure port is clean, and the sensor has no external corrosion or damage. Proceed to Step 4.
  Not OK - The sensor has a clogged pressure port, visible external damage from impact, or visible corrosion.
  Repair: Replace the sensor.
Check XA2 I/O Module
1. Park the machine. Turn the key switch to the ON position.
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  Illustration 6 g03643619
2. Inspect the module. Note the color and sequence of the lights on top.
3. Power-on LED (2) is green. Status LED (1) is yellow or red. The status LED flashes red when an error has been detected.
4. Ensure that the electrical connector is seated.
5. Cycle the key power.
  Expected Result: Power-on LED (2) is solid green, and status LED (1) is flashing yellow.
  Results:
  OK - The LEDs indicate a properly operating module, and no errors are present in the system.
  Not OK - Status LED (1) flashes red, indicating a failure, or the "Rear Mount" module shows diagnostics on the WDS display.
  Repair: Replace the XA2 I/O Module.
  STOP.

Hydraulic Tank Oil Temperature Sensor

This diagnostic code is recorded when the WDS hydraulic tank oil temperature sensor has malfunctioned. Voltage signals of less than 0.3 VDC or greater than 5 VDC can generate this fault. This sensor is used to ensure that the hydraulic oil does not exceed 95° C (203° F). Otherwise, the hydraulic components may be damaged.

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Illustration 7	g03643548

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Illustration 8	g03643772

The possible causes of this diagnostic code are listed below:

Moisture entry into the connector
Electrical harness damage
Damage to the sensor
Damaged XA2 module

Check for Moisture Entry into Connector
1. Park the machine. Turn key start switch to the OFF position.
2. Turn the machine disconnect switch to the OFF position.
3. Disconnect connector "H-C3" from the oil temperature sensor.
4. Thoroughly dry both sides of the connector.
5. Inspect the pins for corrosion.
6. Reassemble the connector with a light coating of dielectric grease.
7. Check the continuity of each pin through the connector.
  Expected Results: All connections are continuous through the connector.
  Results:
  OK - All connections are continuous. Proceed to Step 2.
  Not OK - One or more of the connections did not show continuity, and the diagnostic is still present.
  Repair: Replace the pins and the connector.
Check Electrical Harness
1. Park the machine. Turn key start switch to the ON position.
2. Disconnect connector "H-C3" from the oil temperature sensor.
3. Check pin "1" for 5 VDC.
4. Check pin "2" for ground.
5. Check the continuity of wire R732-BR(Brown) from connector "H-C3" to pin "12" of connector "CC-C1".
  Expected Result: Pin "1" has 5 VDC, pin "2" is continuous to ground, and wire R732-BR(Brown) is continuous.
  Results:
  OK - All pins check fine. Proceed to Step 3.
  Not OK - One or more of the pins did not check out correctly.
  Repair: Inspect the harness for damage. Repair or replace the harness if necessary.
Check Sensor
1. Park the machine. Turn key start switch to the OFF position.
2. Turn the machine disconnect switch to the OFF position.
3. Disconnect connector "H-C3" from the oil temperature sensor.
4. Make sure that the oil level in the hydraulic tank is lower than the port for the temperature sensor. If this action is not performed, hydraulic oil will leak out of the sensor port when the sensor is removed.
5. Remove the sensor from the hydraulic tank.
6. Inspect the sensor for physical damage.
  Expected Result: The sensor has no external corrosion or damage.
  Results:
  OK - The sensor has no visible damage. Proceed to Step 4.
  Not OK - The sensor has visible external damage from impact or visible corrosion, and the sensor does not register a valid temperature.
  Repair: Replace the sensor.
Check XA2 I/O Module
1. Park the machine. Turn the key switch to the ON position.
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  Illustration 9 g03643619
2. Inspect the module. Note the color and sequence of the lights on top.
3. Power-on LED (2) is green. Status LED (1) is yellow or red. The status LED flashes red when an error has been detected.
4. Ensure that the electrical connector is seated.
5. Cycle the key power.
  Expected Result: Power-on LED (2) is solid green, and status LED (1) is flashing yellow.
  Results:
  OK - The LEDs indicate a properly operating module, and no errors are present in the system.
  Not OK - Status LED (1) flashes red, indicating a failure, or the "Rear Mount" module shows diagnostics on the WDS display.
  Repair: Replace the XA2 I/O Module.
  STOP.

Hydraulic Pressure Sensor

This diagnostic code is recorded when the WDS hydraulic pressure sensor has malfunctioned. Voltage signals of less than 0.3 VDC or greater than 5 VDC can generate this fault. Pressure signals of less than −103 kPa (−15 psi) or greater than 34474 kPa (5000 psi) while the engine speed is greater than 500 rpm can also generate this fault.

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Illustration 10	g03643548

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Illustration 11	g03643804

The possible causes of this diagnostic code are listed below:

Moisture entry into the connector
Electrical harness damage
Damage to the sensor
Damaged XA2 module

Check for Moisture Entry into Connector
1. Park the machine. Turn key start switch to the OFF position.
2. Turn the machine disconnect switch to the OFF position.
3. Disconnect connector "R-C2" from the hydraulic pressure sensor.
4. Thoroughly dry both sides of the connector.
5. Inspect the pins for corrosion. Replace the pins if necessary.
6. Reassemble the connector with a light coating of dielectric grease.
7. Check the continuity of each pin through the connector.
  Expected Results: All connections are continuous through the connector.
  Results:
  OK - All connections are continuous. Proceed to Step 2.
  Not OK - One or more of the connections did not show continuity, and the diagnostic is still present.
  Repair: Replace the pins and the connector.
Check Electrical Harness
1. Park the machine. Turn key start switch to the ON position.
2. Disconnect connector "R-C2" from the hydraulic pressure sensor.
3. Check pin "1" for 5 VDC.
4. Check pin "2" for ground.
5. Check the continuity of wire L943-PK(Pink) from connector "R-C2" to pin "38" of connector "RC-C1".
  Expected Result: Pin "1" has 5 VDC, pin "2" is continuous to ground, and wire R732-BR(Brown) is continuous.
  Results:
  OK - All pins check fine. Proceed to Step 3.
  Not OK - One or more of the pins did not check out correctly.
  Repair: Inspect the harness for damage. Repair or replace the harness if necessary.
Check Sensor
1. Park the machine. Turn key start switch to the OFF position.
2. Turn the machine disconnect switch to the OFF position.
3. Disconnect connector "R-C2" from the hydraulic pressure sensor.
4. Make sure that the oil level in the hydraulic tank is lower than the port for the pressure sensor. If this action is not performed, hydraulic oil will leak out of the sensor port when the sensor is removed.
5. Remove the sensor from the fitting.
6. Inspect the sensor for damage or possibly a clogged pressure port in the end of the sensor.
  Expected Result: The pressure port is clean, and the sensor has no external damage.
  Results:
  OK - The pressure port is clean, and the sensor has no external damage. Proceed to Step 4.
  Not OK - The sensor has a clogged pressure port, visible external damage from impact, or visible corrosion, and the sensor does not register a valid pressure.
  Repair: Replace the sensor.
Check XA2 I/O Module
1. Park the machine. Turn the key switch to the ON position.
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  Illustration 12 g03643619
2. Inspect the module. Note the color and sequence of the lights on top.
3. Power-on LED (2) is green. Status LED (1) is yellow or red. The status LED flashes red when an error has been detected.
4. Ensure that the electrical connector is seated.
5. Cycle the key power.
  Expected Result: Power-on LED (2) is solid green, and status LED (1) is flashing yellow.
  Results:
  OK - The LEDs indicate a properly operating module, and no errors are present in the system.
  Not OK - Status LED (1) flashes red, indicating a failure, or the "Rear Mount" module shows diagnostics on the WDS display.
  Repair: Replace the XA2 I/O Module.
  STOP.