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| Illustration 1 | g01294416 |
Connections for the implement pump pressure sensor | |
This diagnostic code is associated with the implement pump pressure sensor. The "Input low error" means that the IQAN-XT2 module has determined that the voltage of the sensor signal circuit is below normal.
The pressure sensor sends a variable voltage input to the module that will indicate the implement pump pressure.
The possible causes of this diagnostic code are listed below:
- The signal circuit for the sensor is open.
- The signal circuit for the sensor is shorted to the +battery circuit.
- The sensor has failed.
- The power circuit or the return circuit is open.
- The module has failed. This is unlikely.
Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of "Input low error" for pin 21 of the IQAN-XT2 module is active before performing this procedure.
Note: Use a digital multimeter for the measurements in this procedure.
Test Step 1. CHECK FOR POWER AT THE SENSOR
- Do not disconnect the harness connector from the sensor.
- At the back of the 3 contact machine harness connector for the sensor, insert 7X-1710 Multimeter Probes along supply contact 2 (wire C530-GN) and along return contact 3 (wire C531-YL) for the voltage supply.
- Turn the key start switch and the disconnect switch to the ON position.
- Measure the DC voltage from contact 2 to contact 3.
Expected Result:
The voltage measurement is 5.0 ± 0.5 DCV.
Results:
- OK - The voltage measurement is 5.0 ± 0.5 DCV. The power supply is correct. Proceed to Test Step 2.
- NOT OK - The voltage measurement is less than 5.0 ± 0.5 DCV. The voltage is not correct. There is an open or a bad connection in the circuit.
Repair: There is a problem in the power supply circuit in the machine harness. Refer to the complete machine Electrical System Schematic. Check all of the connectors that are in the sensor supply circuit and the return circuit. Ensure that all connections are clean, secure and in good condition. Repair the machine harness or replace the machine harness.
STOP
Test Step 2. CHECK THE SIGNAL CIRCUIT FOR THE SENSOR
- Turn the disconnect switch and the key switch to the OFF position.
- Remove the 7X-1710 Multimeter Probes from the back of the machine harness connector for the sensor.
- Disconnect the machine harness connector from the sensor. At the machine harness connector for the sensor, place a jumper wire from contact 3 (wire C531-YL) to contact 1 (wire C529-OR) .
- Disconnect the machine harness connector from the IQAN XT2 module.
- Measure the resistance from return contact IQAN XT2 A0 - 11 (wire C531-YL) to signal contact IQAN XT2 A0 - 21 (wire C529-OR).
Expected Result:
The resistance measurement is less than 5 ohms.
Results:
- OK - The resistance measurement is less than 5 ohms. The return circuit and the signal circuit are correct in the machine harness. Proceed to Test Step 3.
- NOT OK - The resistance is greater than 5 ohms. There is a problem in the machine harness.
Repair: Either the return circuit wire C531-YL or the signal circuit wire C529-OR has a bad connection or an open in the machine harness. Refer to the complete machine Electrical System Schematic. Examine all of the connectors that are in the circuit. Ensure that the connections are clean, secure and in good condition. Repair the machine harness or replace the machine harness.
STOP
Test Step 3. CHECK THE SENSOR SIGNAL CIRCUIT FOR A SHORT TO THE +BATTERY CIRCUIT
- The key start switch and the disconnect switch remain in the OFF position.
- The machine harness remains disconnected from the sensor. Remove the jumper wire that was installed in the previous step.
- The machine harness connector remains disconnected from the IQAN-XT2 module.
- At the machine harness connector for the IQAN-XT2 module, measure the resistance from the signal contact IQAN XT2 A0 - 21 (wire C529-OR) of the machine harness to all contacts that are used in the machine harness connector for the IQAN-XT2 module.
Expected Result:
Each resistance measurement is greater than 5000 ohms.
Results:
- OK - Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 4.
- NOT OK - One or more of the resistance measurements is not correct. There is a short in the machine harness.
Repair: The short is between signal wire C529-OR) and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness.
STOP
Test Step 4. CHECK THE STATUS OF THE DIAGNOSTIC CODE
- Inspect the harness connectors and clean the contacts of the harness connectors and check the wires for damage to the insulation that is caused by excessive heat, battery acid, or chafing.
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the sensor circuit.
- Reconnect all harness connectors. Make sure that the connectors are fully seated and the clips for each connector are completely fastened.
- Turn the disconnect switch and the key start switch to the ON position.
- Operate the machine.
- Determine if the "Input low error" for pin 21 of the IQAN-XT2 module is active.
Expected Result:
The "Input low error" for pin 21 of the IQAN-XT2 module is active.
Results:
- YES - The "Input low error" for pin 21 of the IQAN-XT2 module is active. The problem has not been corrected. The sensor may have failed or the module may be faulty.
Repair: If a problem is not found in the machine harness, replace the pressure sensor. If the problem is still present after replacement of the sensor, the module may be faulty.Prior to replacing a module, always contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the cause of the diagnostic code is not found, replace the module.
STOP
- NO - The "Input low error" for pin 21 of the IQAN-XT2 module is not active. The problem does not exist at this time.
Repair: The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.
STOP