Note: Some of the following codes may not be applicable for certain applications.
| Diagnostic Codes Table | |||
|---|---|---|---|
| CDL Code | J1939 Code | Code Description | Comments |
| 41-3 | 678-3 | 8 VDC Supply : Voltage Above Normal | The code is logged. |
| 41-4 | 678-4 | 8 VDC Supply : Voltage Below Normal | The code is logged. |
| 262-3 | 3509-3 | 5 Volt Sensor DC Power Supply : Voltage Above Normal | The code is logged.
All sensors are set to default values. |
| 262-4 | 3509-4 | 5 Volt Sensor DC Power Supply : Voltage Below Normal | The code is logged.
All sensors are set to default values. |
| 274-21 | 108-21 | Atmospheric Pressure Sensor : Data Drifted Low | The code is logged.
The 5 VDC supply to the sensor has been lost. |
| 460-21 | 5580-21 | Fuel Pressure Sensor - After Fuel Filter : Data Drifted Low | The code is logged.
The 5 VDC supply to the sensor has been lost. |
| 1785-21 | 3563-21 | Intake Manifold Pressure Sensor : Data Drifted Low | The code is logged.
The 5 VDC supply to the sensor has been lost. |
| 2131-3 | 3510-3 | 5 v Sensor DC Power Supply #2 : Voltage Above Normal | The code is logged.
Engine power may be derated. |
| 2131-4 | 3510-4 | 5 v Sensor DC Power Supply #2 : Voltage Below Normal | The code is logged.
Engine power may be derated. |
System Operation
The Electronic Control Module (ECM) supplies a regulated voltage of 5.0 ± 0.2 VDC to the sensors.
The supply voltage for the sensors is routed from the ECM to terminal 1 of each sensor connector. The sensor return for the sensors is routed from the ECM to terminal 2 of each sensor connector. The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.
Note: The sensors are not protected from overvoltage. A short from the supply line to the +Battery may damage the sensors. If any of the diagnostic codes are active, a sensor may have been damaged. Repair the sensor supply and check for any active sensor diagnostic codes in order to determine if a sensor has been damaged.
| |
| Illustration 1 | g03018936 |
Note: The diagram above is a simplified schematic of the ECM - relay circuit. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of the Electrical Schematic for the complete schematic.
| |
| Illustration 2 | g01240891 |
|
Sensor connector (1) 5 V or 8 V sensor supply (2) Sensor return (3) Signal | |
| Troubleshooting Test Steps | Values | Results |
1. Determine the Code A. Connect Cat ET to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Determine if a diagnostic trouble code is present. |
Codes |
Result: A -3 or -4 code is present. Inspect the wiring at each sensor. Look for broken wiring or problems with a connector. Make the necessary repairs. Result: A -21 code is present. There is an intermittent loss or solid loss of 5 V supply to the sensor. Proceed to Test Step 2. |
2. Check the Sensor Supply A. Turn the keyswitch to the ON position. Do not start the engine. B. Perform the "Wiggle Test" in Cat ET. C. Unplug the suspect sensor. D. Place a jumper wire across pin 1 to pin 2. |
Short circuit |
Result: A 41-4, a 2131-4 or a 262-4 code is activated. Remove the sensor. Check the sensor passage for a blockage or obstruction. Also, check for moisture frozen in the lines. If blockage is not found, replace the sensor. Verify the repair. Result: A 41-4, a 2131-4 or a 262-4 code is not activated. The problem is in the wiring from the ECM to the sensor. Repair the wiring or replace the wiring. Verify the repair. |
Complete the procedure in the order in which the steps are listed.
If the procedure corrected the issue, return the engine to service.
If the procedure did not correct the issue, Contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).