BUSHING ASSEM. 4N5681 - Caterpillar

During normal operation, each pressure sensor outputs a signal voltage that accurately represents the pressure that is sensed by the sensor. However, certain circuit conditions can cause a signal voltage to become inaccurate.During each key on event of at least 2 seconds, the Electronic Control Module (ECM) evaluates the signal voltage from each pressure sensor. The ECM compares each signal voltage to a reference voltage. The reference voltage that is used depends on the sensor.If a signal voltage is close to the reference voltage, the ECM will internally adjust the signal voltage. The internal adjustment causes the pressure value for the sensor to be correct. This process is called automatic sensor calibration.If a signal voltage is not close to the reference voltage, the ECM will not internally adjust the signal voltage. The ECM will set a fault code that indicates there is a problem with the signal voltage.Table 1 indicates the maximum error that is permitted for each sensor, and the reference for that sensor. Refer to the troubleshooting procedure to determine the root cause of the incorrect signal voltage.
Table 1
J1939 Code and Description CDL Code and Description Comments
3563-13
Engine Intake Manifold #1 Absolute Pressure : Out of Calibration 1785-13
Intake Manifold Pressure Sensor : Out of Calibration During key on, the signal voltage from the intake manifold pressure sensor indicated an intake manifold pressure greater than +/- 18 kPa (3 psi).
Reference sensor: Atmospheric Pressure Sensor
3563–21
Engine Intake Manifold #1 Absolute Pressure : Data Drifted Low 1785–21
Intake Manifold Pressure Sensor : Data Drifted Low The 5 VDC supply to the sensor has been lost.
The code is logged.
Table 2
Troubleshooting Test Steps Values Results
1. Check for Codes
Note: The engine coolant temperature must be greater than 0° C (32° F) before beginning this procedure.
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
B. Look for active codes that are associated with the system for the event code.
Codes
Result: An associated code is active.
Repair: Troubleshoot any associated codes before continuing with this test.
Result: A code is active or logged.
Proceed to Test Step 2.
2. Check for Debris
A. Turn the keyswitch to the OFF position.
B. Check the sensor for debris.
C. If applicable, check the reference sensor for debris.
D. Check the sensor measurement port for blockage by debris.
E. If debris is found, clear the debris from the measurement port and replace the sensor.
F. Connect Cat ET.
G. Use Cat ET to monitor the following code:
- Codes
Debris
Result: The sensor measurement port is not blocked by debris.
Proceed to Test Step 3.
Result: A -13 code is not active.
Return to service.
Result: A -13 code is active.
Repair: Replace the sensor. If more than one -13 code is active and the codes have a reference sensor, replace the reference sensor.
If the problem is not resolved, proceed to Test Step 3.
3. Inspect the Sensor Connector
A. Turn the keyswitch to the OFF position.
B. Inspect the sensor connector for moisture and corrosion.
Moisture
Result: The sensor connector does not have moisture or corrosion.
Proceed to Test Step 5.
Result: The sensor connector has moisture and/or corrosion.
Proceed to Test Step 4.
4. Remove any