Use this procedure to troubleshoot the following diagnostic codes:
CDL Code and Description |
---|
100-3 Engine Oil Pressure Sensor : Voltage Above Normal |
100-4 Engine Oil Pressure Sensor : Voltage Below Normal |
110-3 Engine Coolant Temperature Sensor : Voltage Above Normal |
110-4 Engine Coolant Temperature Sensor : Voltage Below Normal |
172-3 Intake Manifold Air Temperature Sensor : Voltage Above Normal |
172-4 Intake Manifold Air Temperature Sensor : Voltage Below Normal |
175-3 Engine Oil Temperature Sensor : Voltage Above Normal |
175-4 Engine Oil Temperature Sensor : Voltage Below Normal |
542-3 Engine Oil Pressure Sensor - Before Oil Filter : Voltage Above Normal |
542-4 Engine Oil Pressure Sensor - Before Oil Filter : Voltage Below Normal |
Note: The engine coolant temperature sensor is a 2-wire passive sensor. The Electronic Control Module (ECM) applies a voltage to the signal wire of the sensor. As the temperature of the sensing element changes, the resistance of the sensor circuitry changes proportionally. The ECM detects a voltage drop across the resistance of the sensor and equates the voltage drop to the temperature measurement of the sensor. The sensor does not require a separate supply voltage from the ECM.
Background Information
For analog sensors, the ECM continuously creates a pull-up voltage on the signal wire for each sensor. The ECM uses this pull-up voltage in order to detect a problem in the signal circuit. When the ECM detects voltage that is above a threshold on the signal wire, the ECM activates a -3 diagnostic code. When the ECM detects voltage that is below a threshold on the signal wire, the ECM activates a -4 diagnostic code.
Note: Wait at least 30 seconds in order for the ECM to detect the diagnostic code.
A -3 code is probably caused by a problem in an engine harness. There may be an open circuit in a harness, or a short circuit to a positive voltage source in a harness. The next likely cause is a sensor problem. The least likely cause is a problem with the ECM.
A -4 code is probably caused by a short circuit to ground in an engine harness. The next likely cause is a sensor problem. The least likely cause is a problem with the ECM.
This troubleshooting procedure may generate additional diagnostic codes. Ensure that you continue to troubleshoot the original diagnostic code. Clear the diagnostic code after the problem is resolved.
Illustration 1 | g02334898 |
Schematic for the analog sensors |
Test Step 1. Inspect the Electrical Connectors and the Wiring
- Set the engine control to the OFF/RESET mode.
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Illustration 2 g01252046 Location of the analog sensors (left front engine view)
(1) Inlet air temperature sensor
(2) Engine coolant temperature sensor
(3) Pressure sensor for unfiltered oil
(4) Pressure sensor for filtered oil
(5) Oil temperature sensorShow/hide tableIllustration 3 g01395887 Location of the ECM connectors that are for the analog sensors
(6) P1 ECM connectorNote: For the following steps, refer to Troubleshooting, "Inspecting Electrical Connectors".
- Thoroughly inspect the connectors for sensors (1), (2), (3), (4), and (5). Also, thoroughly inspect ECM connectors (6).
- Check the allen head screw for each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for the correct torque value.
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Illustration 4 g02334880 P1 ECM connector
(P1-14) Inlet air temperature
(P1-17) Engine oil temperature
(P1-24) Filtered engine oil pressure
(P1-26) Unfiltered engine oil pressure
(P1-27) Engine coolant temperatureShow/hide tableIllustration 5 g01155187 Locations of the terminals for the 2-pin connector Show/hide tableIllustration 6 g01159881 Locations of the terminals for the 3-pin connector - Perform a
45 N (10 lb) pull test on each of the wires that are associated with the circuits for the analog sensors. - Check the harnesses and wiring for abrasion and for pinch points from each 5 V sensor to the ECM.
Expected Result:
All of the connectors, pins, and sockets are connected properly. The connectors and the wiring do not have corrosion, abrasion, or pinch points.
Results:
- OK - All of the connectors, pins, and sockets are connected properly. The connectors and the wiring do not have corrosion, abrasion, or pinch points. The components are in good condition with proper connections. Proceed to Test Step 2.
- Not OK - At least one of the connectors, pins, and/or sockets are not connected properly. At least one of the connectors and/or the wiring have corrosion, abrasion, and/or pinch points.
Repair: Perform the necessary repairs and/or replace parts, if necessary.
STOP
Test Step 2. Check for Diagnostic Codes Related to the Sensor Supply
- Establish communication between Caterpillar Electronic Technician (ET) and the engine ECM. Refer to Troubleshooting, "Electronic Service Tools", if necessary.
- Set the engine control to the STOP mode.
- Observe the "Active Diagnostic" screen on Cat ET. Allow 30 seconds for any codes to activate. Look for these codes for the sensor supply:
- 262-3 5 Volt Sensor DC Power Supply : Voltage Above Normal
- 262-4 5 Volt Sensor DC Power Supply : Voltage Below Normal
Expected Result:
There are no active diagnostic codes for the sensor supply.
Results:
- No Sensor Supply Codes Active - There are no active sensor supply diagnostic codes. Proceed to Test Step 3.
- Active 262-3 or 262-4 - There is an active sensor supply diagnostic code. Do not use this procedure for a problem related to the power supply for the sensors.
Repair: Refer to Troubleshooting, "+5V Sensor Voltage Supply".
If necessary, return to this procedure to troubleshoot the analog sensor after the sensor supply diagnostic code has been resolved.
STOP
Test Step 3. Check for Active Diagnostic Codes for the Analog Sensors
- Observe the "Active Diagnostic" screen on Cat ET. Wait at least 30 seconds so that any codes may become activated. Check if any of the following diagnostic codes are active:
- 100-3 Engine Oil Pressure Sensor : Voltage Above Normal
- 100-4 Engine Oil Pressure Sensor : Voltage Below Normal
- 110-3 Engine Coolant Temperature Sensor : Voltage Above Normal
- 110-4 Engine Coolant Temperature Sensor : Voltage Below Normal
- 172-3 Intake Manifold Air Temperature Sensor : Voltage Above Normal
- 172-4 Intake Manifold Air Temperature Sensor : Voltage Below Normal
- 175-3 Engine Oil Temperature Sensor : Voltage Above Normal
- 175-4 Engine Oil Temperature Sensor : Voltage Below Normal
- 542-3 Engine Oil Pressure Sensor - Before Oil Filter : Voltage Above Normal
- 542-4 Engine Oil Pressure Sensor - Before Oil Filter : Voltage Below Normal
- If one of the above codes is active, identify the type of diagnostic according to the condition: the diagnostic code is either a -3 diagnostic code or a -4 diagnostic code.
Expected Result:
None of the above codes are active.
Results:
- No active codes - None of the above codes are active.
Repair: If any of the above codes are logged and the engine is not running properly, refer to Troubleshooting, "Troubleshooting Without a Diagnostic Code".
If the engine is running properly and a code is logged, there may be an intermittent problem in the harness or in a connector. Refer to Troubleshooting, "Inspecting Electrical Connectors" for information that is related to troubleshooting intermittent electrical problems.
STOP
- -3 Active - There is an active -3 diagnostic code. If you are troubleshooting the sensor for engine coolant temperature, proceed to Test Step 5. Otherwise, proceed to Test Step 4.
- -4 Active - There is an active -4 diagnostic code. Proceed to Test Step 5.
Test Step 4. Check the Supply Voltage at the Sensor Connector
- Disconnect the suspect sensor the engine harness at the sensor connector.
- At the sensor connector for the suspect sensor, measure the voltage between terminals A and B.
Expected Result:
The voltage between terminals A and B is between 4.5 VDC and 5.5 VDC.
Results:
- OK - The voltage is within the specified range at the sensor connector. Proceed to Test Step 5.
- Not OK - The voltage is not within the specified range at the sensor connector.
Repair: There is a problem with the sensor supply circuit for the suspect sensor. Troubleshoot the supply circuit before continuing with this test procedure. Refer to Troubleshooting, "+5V Sensor Voltage Supply" for details related to troubleshooting the sensor supply.
STOP
Test Step 5. Check for a Pull-Up Voltage at the Sensor
- Ensure that the suspect sensor is disconnected from the engine harness.
- At the harness connector for the suspect sensor, measure the voltage between terminals B and C, or between terminals 1 and 2. Record this value.
- At the harness connector for the other analog sensors on the engine, measure the voltage between terminals B and C or terminals 1 and 2. Record this value.
Note: Due to the internal electrical circuitry within the ECM, pull-up voltages can vary for different harness configurations on different engines. Ensure that the pull-up voltage measurement compares to the measurement for the other analog sensors on your engine. Also, ensure that the pull-up voltage is not battery voltage.
Expected Result:
The pull-up voltage is within ±0.5 V of the other analog sensor circuits on the engine.
Results:
- OK - The pull-up voltage is within ±0.5 V of the other analog sensor circuits.
Repair: The signal wire and the return wire for the suspect sensor are OK.
There appears to be a problem with the sensor. Before you replace the suspect sensor, connect the new sensor to the engine harness and check for active diagnostic codes. Be sure to power down the ECM before you check for active codes.
If the problem has been resolved, install the new sensor and return the engine to service.
If the problem persists, continue troubleshooting the code.
STOP
- Not OK - The voltage measurement does not compare to the pull-up voltages of the other analog sensors on the engine. There may be an open circuit or a short circuit in the harness. There may be a problem with the ECM. Proceed to Test Step 6.
Test Step 6. Check the Pull-Up Voltage at the ECM
- Set the engine control to the OFF/RESET mode.
- Fabricate a jumper wire that is long enough to create a test circuit at the ECM. Crimp a connector socket to one end of the jumper wire.
- Use a wire removal tool to remove the signal wire for the suspect sensor from the P1 ECM connector. Refer to Illustration 1 to identify the correct terminal location at the ECM.
- Insert the jumper wire into the terminal location at the P1 ECM connector for the signal wire of the suspect sensor.
- Insert a 7X-1710 Multimeter Probe into P1-3 (sensor return) at the ECM connector.
- Set the engine control to the STOP mode.
- Use a multimeter to measure the pull-up voltage between the two test leads.
Expected Result:
The pull-up voltage for the suspect sensor at the ECM is within ±0.5 V of the previously measured value.
Results:
- OK - The pull-up voltage for the suspect sensor at the ECM is within specifications. The pull-up voltage at the ECM is correct. There is a problem with the signal wire between P1 and the harness connector for the sensor. There may be a problem with a connector.
Repair: Perform the following procedure:
Set the engine control to the OFF/RESET mode.
Disconnect the multimeter leads.
Restore the wiring at the P1 connector. Pull on the wire in order to verify proper installation of the terminal.
Verify that the wiring and/or connectors are OK. Repair any faulty wiring and/or connectors, when possible. Replace any wiring and/or connectors, if necessary. Refer to Troubleshooting, "Inspecting Electrical Connectors".
STOP
- Not OK - The pull-up voltage for the suspect sensor at the ECM is not within specifications.
STOP