| Diagnostic Codes Table | ||
|---|---|---|
| J1939 Code and Description | Conditions which Generate this Code | System Response |
| 168-3 Battery Potential / Power Input #1 : Voltage Above Normal |
Electrical System Voltage : Voltage Above Normal | The code is logged. |
| 168-4 Battery Potential / Power Input #1 : Voltage Below Normal |
Electrical System Voltage : Voltage Below Normal | The code is logged. |
The engine ECM requires the keyswitch to be in the ON position in order to maintain communications with Caterpillar Electronic Technician (ET).
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| Illustration 1 | g03658891 |
Schematic for the electrical power supply (typical example). | |
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| Illustration 2 | g03321350 |
Location of the J1/P1 and the J2/P2 ECM connectors (typical engine view). (1) J1/P1 ECM connector (2) J2/P2 ECM connector | |
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| Illustration 3 | g03658881 |
P2 ECM connector (P1-43) + Starter enable relay (P1-51) Return | |
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| Illustration 4 | g01206554 |
P1 ECM connector (P1-48) +Battery (P1-52) +Battery (P1-53) +Battery (P1-55) +Battery (P1-57) +Battery (P1-61) −Battery (P1-63) −Battery (P1-65) −Battery (P1-67) −Battery (P1-69) −Battery (P1-70) Keyswitch | |
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| Illustration 5 | g03678643 |
Engine interface connector (Terminal AC) Auxiliary 1 + Battery (Terminal AH) Auxiliary 1 + Battery (Terminal AJ) Auxiliary 2 + Battery (Terminal AK) Emergency Stop (Terminal AL) Auxiliary 2 + Battery (Terminal AM) Emergency Stop 2 (Terminal AT) Auxiliary 1 − Battery (Terminal AV) Auxiliary 1 − Battery (Terminal AX) Auxiliary 2 − Battery (Terminal AZ) Auxiliary 2 − Battery (Terminal BC) Keyswitch | |
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| Illustration 6 | g03677160 |
Power interface connector 1 (37 pin connector) (Terminal 14) Auxiliary 2 + Battery (Terminal 15) Auxiliary 2 + Battery (Terminal 16) Auxiliary 2 − Battery (Terminal 17) Auxiliary 2 − Battery (Terminal 35) Emergency Stop 2 | |
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| Illustration 7 | g03677162 |
Power interface connector 2 (25 pin connector) (Terminal 2) + Battery (Terminal 3) + Battery (Terminal 4) + Battery (Terminal 5) − Battery (Terminal 6) − Battery (Terminal 8) − Battery (Terminal 14) Auxiliary 1 + Battery (Terminal 15) Auxiliary 1 + Battery (Terminal 16) Auxiliary 1 − Battery (Terminal 17) Auxiliary 1 − Battery (Terminal 21) Emergency Stop | |
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| Illustration 8 | g03323077 |
Terminal locations for the ECM relay and the connector (typical example) (3) ECM relay (Terminal 1) +Battery (Terminal 2) Relay ground (Terminal 3) Electrical power to the ECM (Terminal 5) Relay control | |
1. Inspect Electrical Connectors and Wiring A. Turn the main disconnect switch to the OFF position. B. Thoroughly inspect the ECM connectors J1/P1. Inspect all of the other connectors in the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details. C. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit. D. Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values. E. Check the harness and the wiring for abrasion and for pinch points. |
Connectors |
Result: The connectors and wiring appear to be OK. Proceed to Test Step 2. Result: The connectors and/or wiring are NOT OK. 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 between the following wires: - P1-48 and P1-61 - P1-52 and P1-63 - P1-53 and P1-65 - P1-55 and P1-67 - P1-57 and P1-69 - P1-70 and P1-63 |
ECM Voltage |
Result: The voltage is 24 ± 3 VDC. Repair: The ECM is receiving the correct voltage. The problem may be intermittent. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect". Verify that the repair eliminated the problem. 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. B. Check the charging circuit. |
Charging Circuit |
Result: The charging system is OK. Proceed to Test Step 4. Result: The charging system is NOT OK. Repair: 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. |
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).