G3306B Petroleum Generator Set Engines Caterpillar

Electrical Power Supply - Test

Usage:

Use this procedure to troubleshoot the electrical system if a problem is suspected with the circuit for electrical power supply. Also use this procedure if one of the diagnostic codes in Table 1 is active or easily repeated.

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Table 1
Diagnostic Codes Table
Description	Conditions which Generate this Code	System Response
158-2 Keyswitch Battery Potential : Erratic, Intermittent, or Incorrect	The Electronic Control Module (ECM) has detected three transitions of the signal for the keyswitch within one second.	The code is logged. The red stop lamp is illuminated. The engine is shut down. The ECM is latched.
168-2 Battery Potential / Power Input 1 : Erratic, Intermittent, or Incorrect	The input voltage to the ECM has dropped below 6 v and the input voltage has risen above 9 v three times within 7 seconds.	The code is logged. The amber warning lamp is illuminated.
168-3 Battery Potential / Power Input 1 : Voltage Above Normal	The input voltage to the ECM has risen above 32 v for one second.	The code is logged. The amber warning lamp is illuminated. The ECM will use default values for all of the engine sensors that are powered. The status of the "Battery Voltage" parameter is reported as "Data Error" by Caterpillar Electronic Technician (ET).
168-4 Battery Potential / Power Input 1 : Voltage Below Normal	The input voltage to the ECM has dropped below 18 v for one second.	The code is logged. The red stop lamp is illuminated. The engine is shut down. The ECM will use default values for all of the engine sensors that are powered. The status of the "Battery Voltage" parameter is reported as "Data Error" by Cat ET.
3542-3 Requested Engine Control Mode : Voltage Above Normal	The ECM has detected a simultaneous open circuit condition for the engine stop circuit and the start circuit for at least 2 seconds.	The code is logged. The red stop lamp is illuminated. The engine is shut down.
3542-4 Requested Engine Control Mode : Voltage Below Normal	The ECM has detected the simultaneous grounding of the engine stop circuit and the start circuit for at least 2 seconds.	The code is logged. The red stop lamp is illuminated. The engine is shut down.

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Illustration 1	g01962149
Schematic for the electrical power supply

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Illustration 2	g03430376
Locations of the components for the electrical power supply (typical left side engine view) (1) Display panel (2) Breaker panel (3) ECM

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Illustration 3	g01970015
Locations of the components at the ECM panel that are associated with the electrical power supply (typical left front engine view) (4) J1/P1 ECM connectors (5) Harness connector for the breaker panel (6) Interconnect harness connector

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Illustration 4	g01970074
Locations of the circuit breakers (typical right side engine view) (7) Circuit breaker for the ECM (15 amp) (8) Circuit breaker for the auxiliary circuit (20 amp) (9) Circuit breaker for the starting system (40 amp) (10) Circuit breaker for the alternator (40 amp)

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Illustration 5	g01970754
Terminal locations at the P1 ECM connector that are for the electrical power supply (P1-1) -Battery (P1-2) -Battery (P1-3) -Battery (P1-7) +Battery (P1-8) +Battery (P1-9) -Battery (P1-10) -Battery (P1-15) +Battery (P1-16) +Battery (P1-35) Digital return (P1-40) Keyswitch (P1-50) Stop mode (P1-51) Run mode

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Illustration 6	g01970796
Terminal locations at the interconnect harness connector that are for the electrical power supply (Terminal h) Stop mode (Terminal r) Digital return (Terminal w) Keyswitch (Terminal x) -Battery (Terminal z) +Battery (Terminal O) Run Mode

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Illustration 7	g01926235
Connections at the terminal strip that is in the display panel (Terminal 9) Engine stop signal (Terminal 10) Run mode (Terminal 11) Return (Terminal 15) Keyswitch power (Terminal 16) −Battery (Terminal 17) +Battery

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Illustration 8	g01970799
Terminal locations at the connector for the breaker panel that are for the electrical power supply (Terminal A) +Battery (Terminal B) +Battery (Terminal C) +Battery (Terminal D) +Battery (Terminal F) -Battery (Terminal G) -Battery (Terminal H) -Battery (Terminal J) -Battery

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Table 2
1. Check for Logged Codes or Active Codes A. Establish communication between Cat^® Electronic Technician (Cat^® ET) and the engine ECM. Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Determine if the code is active or logged.	Codes	Results: A 158-2 code is logged or active. Proceed to Test Step 2. Results: A 168-2 code is logged or active. Proceed to Test Step 3. Results: A -4 code is logged or active.
1. Inspect the Electrical Connectors and the Wiring A. Turn the main disconnect switch to the OFF position. B. Thoroughly inspect the ECM connectors. Also, thoroughly inspect the other connectors for the electrical power circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the proper procedure for inspecting the connectors and the wiring.	Electrical connectors	Results: The connectors and wiring appear to be OK. Proceed to Test Step 2. Results: There is a problem in the connectors and/or wiring. Repair The connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are coupled. Verify that the repair eliminated the problem.
2. Check the Voltage to the ECM A. Disconnect the ECM connector J1/P1. B. Restore the electrical power to the ECM. C. Measure the voltage at the ECM. Measure the voltage between P1-53 and P1-65. Measure the voltage between P1-52 and P1-63.	ECM voltage	Result: The voltage is 24 ± 3 VDC. The ECM is receiving the correct voltage. The problem may be intermittent. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect". Result: The voltage is less than 24 ± 3 VDC. The wiring or components between the battery and the ECM may be preventing the voltage from reaching the ECM. Proceed to Test Step 3
3. Check the Charging Circuit A. Turn the main disconnect switch to the OFF position. A. Check the charging circuit.	Charging circuit	Result: The charging system is OK. Proceed to Test Step 4. Result: The charging system is not OK. There is a problem with the charging system. Make the necessary repairs. Refer to Special Instruction, REHS0354, "Charging System Troubleshooting". Verify that the repair eliminated the problem.
4. Load Test the Battery A. Load-test the battery. Refer to Systems Operation and Testing and Adjusting, "Battery - Test"	Load test	Result: The battery voltage is low or the battery did not pass the load test. Repair: Recharge or replace the faulty batteries. Verify that the repair eliminated the problem. Result: The batteries pass the load test. The measured voltage is between 11.5 VDC and 13.5 VDC for a 12 v system. The measured voltage is between 23.0 VDC and 27.0 VDC for a 24 v system. Proceed to Test Step 5
5. Check the Voltage at the ECM Relay A. Remove the wire from terminal 30 of the ECM relay . B. Restore the electrical power to the ECM. C. Measure the voltage from the wire to the −Battery terminal. D. Turn the main disconnect switch to the OFF position. E. Reconnect the wire to terminal 30 of the ECM relay .	ECM relay voltage	Result: The voltage is 24 ± 3 VDC. Proceed to Test Step 6 Result: The voltage is not 24 ± 3 VDC. Repair: If voltage is present at the breaker for the ECM, repair the wire between the breaker for the ECM and the ECM relay. If voltage is not present at the breaker for the ECM, check the wiring between the battery and the breaker for the ECM. Verify that the breaker for the ECM is not tripped and that the breaker for the ECM is operating correctly. Verify that the repair eliminated the problem.
6. Check the Voltage at Terminal 87A of the ECM Relay A. Remove the wire from terminal 87A of the ECM relay . B. Restore the electrical power to the ECM. C. Measure the voltage from the wire to the −Battery terminal. D. Reconnect the wire to terminal 87Aof the ECM relay .	Voltage	Result: The voltage is 24 ± 3 VDC. Repair: The wiring between the ECM relay and the ECM connector P1 is damaged. Repair the wiring or replace the wiring. Verify that the repair eliminated the problem. Result: The voltage is not 24 ± 3 VDC. Repair: If the coil of the ECM relay is not energized, the contact of the ECM relay is damaged. Replace the ECM relay. Verify that the repair eliminated the problem.