C175-16 Petroleum Engine Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the passive sensors. Also, use this procedure if any one of the diagnostic codes in Table 1 is active or easily repeated.

Table 1

Diagnostic Codes Table
J1939 Code and Description	CDL Code and Description	System Response
52-3 Engine Intercooler Temperature : Voltage Above Normal	279-3 Aftercooler Coolant Temperature Sensor (Front) : Voltage Above Normal	The ECM detects signal voltage that is greater than 4.95 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. The code is logged. The value of the parameter is set to 90 °C (194 °F). The engine will not enter cold mode while the code is active.
52-4 Engine Intercooler Temperature : Voltage Below Normal	279-4 Aftercooler Coolant Temperature Sensor (Front) : Voltage Below Normal	The ECM detects signal voltage that is less than 0.2 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. The code is logged. The value of the parameter is set to 90 °C (194 °F). The engine will not enter cold mode while the code is active.
105-03 Engine Intake Manifold 1 Temperature : Voltage Above Normal	172-03 Intake Manifold Air Temperature Sensor : Voltage Above Normal	The ECM detects signal voltage that is greater than 4.95 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. Ambient temperature must be greater than −35 °C (−31 °F) to allow logging of this diagnostic code. The value of the parameter is set to 85 °C (185 °F).
105-04 Engine Intake Manifold 1 Temperature : Voltage Below Normal	172-04 Intake Manifold Air Temperature Sensor : Voltage Below Normal	The ECM detects signal voltage that is less than 0.2 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. Ambient temperature must be less than 140 °C (284 °F) to allow logging of this diagnostic code. The value of the parameter is set to 85 °C (185 °F).
110-3 Engine Coolant Temperature : Voltage Above Normal	110-3 Engine Coolant Temperature Sensor : Voltage Above Normal	The Electronic Control Module (ECM) detects signal voltage that is greater than 4.95 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. The code is logged after 7 minutes. The value of the parameter is set to 90 °C (194 °F). The engine will not enter cold mode while the code is active.
110-4 Engine Coolant Temperature : Voltage Below Normal	110-4 Engine Coolant Temperature Sensor : Voltage Below Normal	The ECM detects signal voltage that is less than 0.2 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. The code is logged. The value of the parameter is set to 90 °C (194 °F). The engine will not enter cold mode while the code is active.
172-3 Engine Air Inlet Temperature : Voltage Above Normal	2526-3 Air Inlet Temperature Sensor : Voltage Above Normal	The ECM detects signal voltage that is greater than 4.95 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. Ambient temperature must be greater than −35 °C (−31 °F) to allow logging of this diagnostic code. The value of the parameter is set to the value of the intake manifold air temperature. If the value of the intake manifold air temperature is less than −30 °C (−22 °F), the value of the parameter is set to −40 °C (−40 °F).
172-4 Engine Air Inlet Temperature : Voltage Below Normal	2526-4 Air Inlet Temperature Sensor : Voltage Below Normal	The ECM detects signal voltage that is less than 0.2 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. The code is logged. The value of the parameter is set to the default value.
174-3 Engine Fuel Temperature 1 : Voltage Above Normal	174-3 Fuel Temperature Sensor : Voltage Above Normal	The ECM detects signal voltage that is greater than 4.95 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. Engine coolant temperature must be above −10 °C (14 °F) to allow logging of this diagnostic code. The value of the parameter is set to the value of the engine coolant temperature.
174-4 Engine Fuel Temperature 1 : Voltage Below Normal	174-4 Fuel Temperature Sensor : Voltage Below Normal	The ECM detects signal voltage that is less than 0.2 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. The code is logged. The value of the parameter is set to the value of the engine coolant temperature.
175-3 Engine Oil Temperature 1 : Voltage Above Normal	175-3 Engine Oil Temperature Sensor : Voltage Above Normal	The ECM detects signal voltage that is greater than 4.95 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. Ambient temperature must be greater than −35 °C (−31 °F) to allow logging of this diagnostic code. The value of the parameter is set to the value of the engine coolant temperature.
175-4 Engine Oil Temperature 1 : Voltage Below Normal	175-4 Engine Oil Temperature Sensor : Voltage Below Normal	The ECM detects signal voltage that is less than 0.2 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. The code is logged. The value of the parameter is set to the value of the engine coolant temperature.
1131-3 Engine Intake Manifold #2 Temperature : Voltage Above Normal	1796-3 Intake Manifold #2 Air Temperature Sensor : Voltage Above Normal	The ECM detects signal voltage that is greater than 4.95 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. Ambient temperature must be greater than −35 °C (−31 °F) to allow logging of this diagnostic code. The value of the parameter is set to 85 °C (185 °F).
1131-4 Engine Intake Manifold #2 Temperature : Voltage Below Normal	1796-4 Intake Manifold #2 Air Temperature Sensor : Voltage Below Normal	The ECM detects signal voltage that is less than 0.2 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. Ambient temperature must be less than 140 °C (284 °F) to allow logging of this diagnostic code . The value of the parameter is set to 85 °C (185 °F).
3468-3 Engine Fuel Temperature 2 : Voltage Above Normal	2323-3 Fuel Rail Temperature Sensor : Voltage Above Normal	The ECM detects signal voltage that is greater than 4.95 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. Ambient temperature must be greater than −35 °C (−31 °F) to allow logging of this diagnostic code. The value of the parameter is set to the value of the engine coolant temperature.
3468-4 Engine Fuel Temperature 2 : Voltage Below Normal	2323-4 Fuel Rail Temperature Sensor : Voltage Below Normal	The ECM detects signal voltage that is less than 0.2 VDC for 8 seconds. The ECM has been powered for at least 2 seconds. Ambient temperature must be less than 140 °C (284 °F) to allow logging of this diagnostic code. The value of the parameter is set to the value of the engine coolant temperature.

System Operation (Primary ECM)

Use this procedure to troubleshoot any suspect problems with the following sensors for the primary ECM:

• Coolant temperature sensor for the engine block outlet

• Fuel temperature sensor for the low-pressure fuel

• Intake manifold temperature sensor

• Oil temperature sensor

• Sensor for the turbocharger compressor inlet temperature

• Temperature sensor for the high-pressure fuel system

Also, use this procedure to troubleshoot any suspect problems with these additional temperature sensors:

• Temperature sensor at the water pump outlet for the engine coolant Temperature Control Module (TCM)

• Temperature sensor at the water pump outlet for the SCAC Temperature control module

Sensor Locations (Primary ECM)

Illustration 1	g02594296
Locations of the primary passive sensors (right side engine view) (1) Intake manifold temperature sensor (2) Temperature sensor at the water pump outlet for the SCAC (3) Fuel temperature sensor for the low-pressure fuel (4) Temperature sensor for the high-pressure fuel system

Illustration 2	g02595179
Locations of the primary passive sensors (top engine view) (5) Inlet air temperature sensor (6) Filtered oil temperature sensor

Illustration 3	g02595238
Locations of the primary passive sensors (left engine view) (7) Coolant pump outlet temperature sensor

Illustration 4	g02783978
Locations of the primary passive sensors (front engine view) (8) Coolant temperature sensor for the engine block outlet

Schematics (Primary ECM)

Illustration 5	g02595758
Schematic for the primary passive sensors if equipped with A4 ECM

Illustration 6	g06322023
Schematic for the primary passive sensors if equipped with A5 ECM

System Operation (Secondary ECM)

This engine utilizes a redundant control system in the case of an ECM failure. If the primary ECM fails, the secondary ECM provides for engine control and engine system monitoring. The secondary ECM utilizes several additional active sensors to monitor engine operation. The following sensors can be found on the engine and are only utilized by the secondary ECM during a failure of the primary ECM:

• Secondary coolant temperature sensor for the engine block outlet

• Secondary intake manifold temperature sensor

• Secondary oil temperature sensor

When troubleshooting these sensors, ensure that the secondary ECM is controlling the engine. except for the secondary intake manifold air temperature sensor, each secondary sensor utilizes the same diagnostic code as the primary version of the sensor. The troubleshooting procedure for each secondary passive sensor is the same as the troubleshooting for the primary passive sensors.

Sensor Locations (Secondary ECM)

Illustration 7	g02596136
Locations of the secondary passive sensors (top engine view) (9) Secondary intake manifold temperature sensor (10) Secondary coolant temperature sensor for the engine block outlet

Illustration 8	g02783983
Locations of the secondary passive sensors (front engine view) (11) Secondary oil temperature sensor

Schematics (Secondary ECM)

Illustration 9	g02784197
Schematic for the secondary passive sensors if equipped with A4 ECM

Illustration 10	g06322034
Schematic for the secondary passive sensors if equipped with A5 ECM

The sensor signal for all the passive sensors is routed to terminal 1 of each sensor connector. The sensor return for the passive sensors is routed from the ECM terminal 2 of each sensor connector.

Table 2

Troubleshooting Test Steps	Values	Results
1. Check for "Active" or "Logged" Diagnostic Codes A. Connect Caterpillar Electronic Technician (ET) to the service tool connector. B. Restore power to the ECM. C. Monitor the diagnostic codes on Cat ET. Check and record any diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic codes to become active. D. Determine if the problem is active and related to one of the following diagnostic codes: -3 -4	Codes	Results: No diagnostic codes are active at this time. Repair: The problem may be intermittent. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect" Results: An active -3 diagnostic code is present. Proceed to Test Step 2 Results: An active -4 diagnostic code is present. Proceed to Test Step 4
2. Check for a Short to the +Battery at the Sensor Connector A. Measure the voltage on the harness side of the sensor connector between pin 1 and pin 2 for the suspect sensor.	+Battery	Results: The supply voltage is less than Battery voltage. Proceed to Test Step 3 Results: The supply voltage is equal to Battery voltage. Repair: There is a short in the harness to the +Battery. Repair the wiring.
3. Create a Short at the Sensor Connector A. Disconnect the suspect sensor. B. Use a wire jumper to create a short between terminal 1 (signal) and terminal 2 (sensor return) at the sensor connector. C. Restore power to the ECM. D. Access the "Active Diagnostic Code" screen on Cat ET. Check for an active -4 diagnostic code for the suspect sensor. Note: Wait at least 30 seconds in order for the diagnostic codes to become active. E. Remove power from the ECM.	Short	Results: A -3 diagnostic code was active before creating the short at the sensor connector. A -4 diagnostic code became active after creating the short at the sensor connector. Repair: Temporarily connect a new sensor to the harness, but do not install the new sensor in the engine. Verify that there are no active diagnostic codes for the sensor. If there are no active diagnostic codes for the sensor, permanently install the new sensor. Clear any logged diagnostic codes. Results: A -3 diagnostic code is still active for the suspect sensor. Proceed to Test Step 5
4. Create an Open at the Suspect Sensor Connector A. Remove power from the ECM. B. Disconnect the sensor connector of the suspect sensor with the active -4 diagnostic code. C. Restore power to the ECM. D. Access the "Active Diagnostic Code" screen on Cat ET. Check for an active -3 diagnostic code. Note: Wait at least 30 seconds in order for the diagnostic codes to become active. E. Remove power from the ECM.	Open	Results: A -4 diagnostic code was active before disconnecting the sensor. A -3 diagnostic code became active after disconnecting the sensor. Repair: Temporarily connect a new sensor to the harness, but do not install the new sensor in the engine. Verify that there are no active diagnostic codes for the sensor. If there are no active diagnostic codes for the sensor, permanently install the new sensor. Clear any logged diagnostic codes. Results: A -4 diagnostic code is still active for the suspect sensor. There is a short circuit between the sensor connector and the ECM. Leave the sensor disconnected. Proceed to Test Step 5
5. Check the Operation of the ECM A. Remove power from the ECM B. Check the operation of the ECM by creating an open at the ECM. C. Remove the signal wire for the suspect sensor from the P1 ECM connector. Refer to Illustration 5 for terminal locations. D. Fabricate a jumper wire that is long enough to create a test circuit between the ECM connector and the ECM ground strap. Crimp a connector socket to one end of the jumper wire. E. Install the jumper wire into the terminal location of the signal wire for the suspect sensor. F. Reconnect the ECM connectors. Ensure that the loose end of the jumper wire does not contact any ground source during the test. G. Restore power to the ECM. Monitor the "Active Diagnostic Code" screen on Cat ET. An open circuit diagnostic code -3 should be active for the suspect sensor. Note: Wait at least 30 seconds in order for the diagnostic codes to become active. H. Check the operation of the ECM by creating a short at the ECM. I. Connect the loose end of the wire jumper to the ECM ground strap. J. Monitor the "Active Diagnostic Code" screen on Cat ET. A -4 diagnostic code should be active when the wire jumper is installed. Note: Wait at least 30 seconds in order for the diagnostic codes to become active. K. Remove the wire jumper. Reconnect all wires and connectors.	ECM	Results: One of the following conditions exists: The -3 diagnostic code is active when the sensor signal wire is disconnected. The -4 diagnostic code is active when the wire jumper is installed. Repair: If the code is active for more than one sensor, the problem is most likely in the return wire for the sensor. Repair the return wire for the sensor or replace the harness. Results: One of the following conditions exists: The -3 diagnostic code is not active when the sensor signal wire is disconnected. The -4 diagnostic code is not active when the wire jumper is installed. Repair: There may be a problem with the ECM. Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN) for assistance.