3512C Marine Auxiliary Generator Set Engines with Dynamic Gas Blending Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the sensor that is for the turbocharger turbine inlet temperature. Also, use this procedure if one of the following diagnostic codes is active or easily repeated.

Table 1

Diagnostic Codes Table
J1939 Code and Description	Conditions which Generate this Code	System Response
1180-3 Engine Turbocharger 2 Turbine Inlet Temperature : Voltage Above Normal	The ECM detects a duty cycle that is greater than 96 percent for ten seconds.	The code is logged. If the signal from the other exhaust temperature sensor is OK, the signal from that sensor is used. If the signal from the other exhaust temperature sensor is not OK, a default value is used.
1180-4 Engine Turbocharger 2 Turbine Inlet Temperature : Voltage Below Normal	The ECM detects a duty cycle that is less than 4 percent for ten seconds.	The code is logged. If the signal from the other exhaust temperature sensor is OK, the signal from that sensor is used. If the signal from the other exhaust temperature sensor is not OK, a default value is used.
1180-8 Engine Turbocharger 2 Turbine Inlet Temperature : Abnormal Frequency, Pulse Width, or Period	The ECM detects a sensor frequency that is greater than 600 Hz or less than 400 Hz.	The code is logged. If the signal from the other exhaust temperature sensor is OK, the signal from that sensor is used. If the signal from the other exhaust temperature sensor is not OK, a default value is used.
1181-3 Engine Turbocharger 1 Turbine Inlet Temperature : Voltage Above Normal	The ECM detects a duty cycle that is greater than 96 percent for ten seconds.	The code is logged. If the signal from the other exhaust temperature sensor is OK, the signal from that sensor is used. If the signal from the other exhaust temperature sensor is not OK, a default value is used.
1181-4 Engine Turbocharger 1 Turbine Inlet Temperature : Voltage Below Normal	The ECM detects a duty cycle that is less than 4 percent for ten seconds.	The code is logged. If the signal from the other exhaust temperature sensor is OK, the signal from that sensor is used. If the signal from the other exhaust temperature sensor is not OK, a default value is used.
1181-8 Engine Turbocharger 1 Turbine Inlet Temperature : Abnormal Frequency, Pulse Width, or Period	The ECM detects a sensor frequency that is greater than 600 Hz or less than 400 Hz.	The code is logged. If the signal from the other exhaust temperature sensor is OK, the signal from that sensor is used. If the signal from the other exhaust temperature sensor is not OK, a default value is used.
2452-8 Generator Total Real Power : Abnormal Frequency, Pulse Width, or Period	The ECM detects a sensor frequency that is greater than 600 Hz or less than 400 Hz.	The code is logged. Gas substitution shuts off.

System Operation

Use this procedure to troubleshoot any suspect problems with the sensor for the left turbocharger turbine inlet temperature or the right turbocharger turbine inlet temperature.

The Pulse Width Modulated Sensor (PWM) provides a signal to the ECM. The PWM signal is used to represent certain engine operating conditions. The sensors receive 8.0 ± 0.4 VDC from a regulated power supply.

The ECM performs an automatic calibration of these sensors whenever the ECM is powered and the engine has been off for at least 5 seconds.

The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.

The following components can cause problems with the power supply:

• Electrical connector or wiring

• Sensor

• ECM

The most likely cause of a problem is a problem with an electrical connector or wiring. The least likely cause is a problem with the ECM.

Illustration 1	g03658061
PWM sensor schematic

Illustration 2	g03658067
P1 ECM connector (P1-4) Digital supply (P1-5) Digital return (P1-18) Digital return

Illustration 3	g03658069
P2 ECM connector (P2-65) Right-hand turbocharger turbine inlet temperature (P2-73) Left-hand turbocharger turbine inlet temperature

Illustration 4	g01159881
Terminal locations at the connectors for the exhaust temperature sensor (Terminal A) Digital sensor supply (Terminal B) Digital return (Terminal C) Signal

Table 2

Troubleshooting Test Steps	Values	Results
1. Check for Active Codes and Logged Codes A. Connect Caterpillar Electronic Technician (ET) to the service tool connector. B. 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. C. Determine if a diagnostic code has occurred several times. Note: A diagnostic code that is logged several times is an indication of an intermittent problem. Most intermittent problems are the result of a bad connection between a socket and a pin in a connector. There could also be a bad connection between a wire and a terminal. D. Look for one or more of the following diagnostic codes that are active or logged: - 1181-3 - 1181-4 - 1181-8 - 1180-3 - 1180-4 - 1180-8	Codes	Result: A code is not active or logged. Repair: There may be an intermittent problem in the harness or in a connector. If an intermittent problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct procedures for inspecting electrical connectors. Result: A code is active or logged. The ECM detects a problem in one of the circuits for the exhaust temperature sensors. Proceed to Test Step 2.
2. Check the Digital Supply Voltage at the Sensor Connector A. Turn the main disconnect switch to the OFF position. B. Disconnect the suspect sensor at the sensor connector. C. Restore the electrical power to the ECM. D. Measure the supply voltage on the harness side of the sensor connector. Measure the voltage between terminal A and terminal B for the suspect sensor.	8.0 ± 0.4 VDC	Result: The supply voltage is 8.0 ± 0.4 VDC. The supply voltage is reaching the sensor connector. Proceed to Test Step 4. Result: The supply voltage is not 8.0 ± 0.4 VDC. The supply voltage is not reaching the sensor connector. Proceed to Test Step 3.
3. Check the Digital Supply Voltage at the ECM A. Turn the main disconnect switch to the OFF position. B. Disconnect the J2/P2 and the J1/P1 ECM connectors. C. Fabricate a jumper wire that is long enough to use as a test lead at the ECM connector. Crimp a connector socket to one end of the jumper wire. D. Remove the wire for the digital supply from terminal location P1-4. Install the jumper wire into the terminal location. E. Connect the J2/P2 ECM connector. F. Restore the electrical power to the ECM. G. Measure the voltage between the jumper wire that is in terminal P1-4 and P1-5. H.Measure the voltage between the jumper wires that are in terminals P1-4 and P1-18. I. Turn the main disconnect switch to the OFF position. J. Restore the wiring to the original configuration.	8.0 ± 0.4 VDC.	Result: The supply voltage at the ECM is 8.0 ± 0.4 VDC. Repair: The supply voltage at the ECM is correct. There is a problem in the wiring between the ECM and the sensor connector. Repair the connectors or wiring and/or replace the connectors or wiring. Verify that the repair eliminated the problem. Result: The supply voltage is not 8.0 ± 0.4 VDC. Repair: The voltage at the ECM is not correct. There is a problem with the ECM. Replace the ECM. Refer to Troubleshooting, "Test ECM Mode". Note: Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN) for assistance. Verify that the repair eliminated the problem.
4. Check the duty cycle for the Suspect Sensor at the Sensor Connector A. Turn the main disconnect switch to the OFF position. B. Remove the sensor signal wire from terminal C on the sensor side of the sensor connector. C. Install a 7X-6370 Adapter Cable As (3-PIN BREAKOUT) at the sensor connector. D. Restore the electrical power to the ECM. E. Measure the duty cycle between the loose signal wire and terminal B (digital return) of the breakout. Note: Set the multimeter to "VDC". Press the "Hz" button twice so that the % symbol is displayed. F. Turn the main disconnect switch to the OFF position. G. Restore the wiring to the original configuration.	Between 10 percent to 90 percent.	Result: The duty cycle is between 10 percent to 90 percent. The duty cycle is correct. Proceed to Test Step 5. Result: The duty cycle is not correct. Repair: Replace the sensor. Verify that no diagnostic codes are active for the suspect sensor before permanently installing the sensor. Verify that the repair eliminated the problem.
5. Check the Duty Cycle for the Suspect Sensor at the ECM A. Turn the main disconnect switch to the OFF position. B. Disconnect the J2/P2 ECM connectors. C. Remove the signal wire for the suspect sensor from the appropriate terminal location at the P2 ECM connector. Refer to Illustration 3 for the terminal locations of the signal wires. D. Install a 257-8718 Adapter Cable As (120-PIN BREAKOUT) at the J2/P2 ECM connectors. E. Connect the J2/P2 ECM connectors. F. Restore the electrical power to the ECM. G. Measure the duty cycle between the sensor signal wire and the appropriate digital return at the breakout t. Note: Set the multimeter to "VDC". Press the "Hz" button twice so that the % symbol is displayed. H. Turn the main disconnect switch to the OFF position. I. Restore all wiring to the original configuration.	Between 10 percent to 90 percent	Result: The duty cycle is between 10 percent to 90 percent. Repair: The duty cycle is correct. The sensor is producing the correct signal. There is a problem with the ECM. Replace the ECM. Refer to Troubleshooting, "Test ECM Mode". Note: Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN) for assistance. Verify that the repair eliminated the problem. Result: The duty cycle is not correct. Repair: The sensor signal is OK at the sensor connector, but the sensor signal is not reaching the ECM. There is a problem in the wiring between the sensor connector and the ECM. Repair the connectors and/or wiring between the sensor connector and the ECM. Verify that the repair eliminated the problem.

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).