C4.4 and C6.6 Engines Caterpillar

Sensor Supply - Test

Usage:

C4.4 448

This procedure covers the following diagnostic codes:

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Table 1
Diagnostic Trouble Codes for Sensor Supplies
J1939 Code	CDL Code	Code Description (code descriptions may vary)	Comments
678-3	41-3	ECU 8 Volts DC Supply : Voltage Above Normal	The ECM detects the following conditions: The 8 VDC supply is more than 8.8 VDC for more than one second. The ECM has been powered for more than 3 seconds. Diagnostic code 168-4 is not active. The ECM will log the diagnostic code and the warning lamp will illuminate when this diagnostic code is active. The engine may be limited to low idle.
678-4	41-4	ECU 8 Volts DC Supply : Voltage Below Normal	The ECM detects the following conditions: The 8 VDC supply is less than 7.2 VDC for more than one second. The ECM has been powered for more than 3 seconds. Diagnostic code 168-4 is not active. The ECM will log the diagnostic code and the warning lamp will illuminate when this diagnostic code is active. The engine may be limited to low idle. An active diagnostic code may not cause any noticeable effect on engine response unless the voltage drops below 6.5 VDC.
3509-3	262-3	Sensor Supply Voltage 1 : Voltage Above Normal	The Electronic Control Module (ECM) detects the following conditions: The 5 VDC supply for the sensors is greater than 5.16 VDC for more than one second. The ECM has been powered for at least 3 seconds. Diagnostic code 168-4 is not active. The warning lamp will come on. The ECM sets all the sensors on the 5 VDC circuit to the default values. The engine will be derated.
3510-3	2131-3	Sensor Supply Voltage 2 : Voltage Above Normal
3509-4	262-4	Sensor Supply Voltage 1 : Voltage Below Normal	The ECM detects the following conditions: The 5 VDC supply for the sensors is less than 4.84 VDC for more than one second. The ECM has been powered for at least 3 seconds. Diagnostic code 168-4 is not active. The warning lamp will come on. The ECM sets all the sensors on the 5 VDC circuit to the default values. The engine will be derated.
3510-4	2131-4	Sensor Supply Voltage 2 : Voltage Below Normal
100-21	100-21	Engine Oil Pressure : Data Drifted Low	The ECM detects no 5 VDC supply to the engine oil pressure sensor.
108-21	3528-21	Barometric Pressure : Data Drifted Low	The ECM detects no 5 VDC supply to the barometric pressure sensor.
3358-21	3385-21	Engine Exhaust Gas Recirculation Inlet Pressure : Data Drifted Low	The ECM detects no 5 VDC supply to the Nox Reduction System (NRS) inlet pressure sensor.
3563-21	1785-21	Engine Intake Manifold #1 Absolute Pressure : Data Drifted Low	The ECM detects no 5 VDC supply to the intake manifold pressure sensor.
5019-21	3511-21	Engine Exhaust Gas Recirculation Outlet Pressure : Data Drifted Low	The ECM detects no 5 VDC supply to the NRS outlet pressure sensor.

Note: A 678-XX diagnostic code indicates a fault in the 8 VDC circuit on the J1/P1 connector. A 3509-XX diagnostic code indicates a fault in the 5 VDC circuit on the J2/P2 connector. A 3510-XX diagnostic code indicates a fault in the 5 VDC circuit on the J1/P1 connector.

The following background information is related to this procedure:

The ECM supplies regulated +8 VDC to the following sensors on the P1 connector:

Digital throttle position sensor 1
Digital throttle position sensor 2

The ECM supplies regulated +8 VDC to the following sensors on the P2 connector:

Primary speed/timing sensor
Secondary speed/timing sensor

The ECM supplies regulated +5 VDC to the following sensors on the P1 connector:

Analog throttle position sensor 1
Analog throttle position sensor 2
DPF inlet temperature sensor
Aftertreatment identification module

The ECM supplies regulated +5 VDC to the following sensors on the P2 connector:

Barometric pressure sensor
Intake manifold air pressure sensor
Fuel pressure sensor
Engine oil pressure sensor
NRS intake pressure sensor
NRS outlet pressure sensor
NRS valve position sensor
Exhaust Back Pressure Regulator (EBPR) position sensor

A diagnostic code can be caused by the following conditions:

A short circuit in the harness
A faulty sensor
An open circuit in the harness

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Illustration 1	g06104117
Typical example of the schematic for the 8VDC supply on P1 and P2

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Illustration 2	g06104168
Typical example of the schematic for the 5 VDC supply on P1

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Illustration 3	g06114261
Typical example of the schematic for the 5 VDC supply on P2

Note: Refer to the application electrical schematic for components that are connected to the 5 V and 8 V supplies on the P1 and P2 connectors.

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Illustration 4	g02315513
Typical example of the fuel rail pressure sensor (1) Sensor ground (3) 5 VDC supply

Note: The position of the terminal for the voltage supply on the fuel rail pressure sensor is different to all other engine pressure sensors.

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Illustration 5	g02315514
Typical example of an engine pressure sensor (1) 5 VDC supply (2) Sensor ground

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Illustration 6	g02315534
Typical example of the connector for the NRS valve (1) 5 VDC supply (2) Sensor ground

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Illustration 7	g03130436
Typical example of the connector for the Exhaust Back Pressure Regulator (EBPR) (1) 5 VDC supply (2) Ground

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Illustration 8	g02087493
Typical example of the connector for the DPF inlet temperature sensor (1) 5 VDC supply (2) Ground

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Illustration 9	g02084579
Typical example of the connector for the aftertreatment identification module (1) 5 VDC supply (6) Ground

Complete the procedure in the order in which the steps are listed.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Determine the Code A. Connect the electronic service tool to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Turn the keyswitch to the ON position. C. Determine if a diagnostic trouble code is present.	Diagnostic Codes	Result: A -3 or -4 code is present. Note which sensor supply has the active diagnostic code. Proceed to Test Step 2.
2. Check for a Failed Sensor A. Connect to the electronic service tool. B. Turn the keyswitch to the ON position. C. Disconnect a sensor on the suspect sensor supply circuit. D. Monitor the electronic service tool when the sensor is disconnected to see if the active code changes to logged. E. Connect the suspect sensor to the wiring harness F. Repeat steps C through E for each sensor on the suspect sensor supply.	Failed Sensor	Result: The suspect sensor supply active code changes to logged when a sensor is unplugged. Repair: Replace the failed sensor. Verify that the repair resolved the fault. Result: The suspect sensor supply active code remains active after all sensors on the sensor supply circuit have been checked. Repair: A failed wiring harness has been detected. Repair or replace the wiring harness. Verify that the repair resolved the fault. If the fault is still present, contact the Dealer Solutions Network (DSN).