SEAL 2870189 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with the power to the engine's Electronic Control Module (ECM) or if any one of the diagnostic codes in Table 2 is active or easily repeated. Refer to Troubleshooting, "Event Code List" for the default conditions for event codes.
Table 1
Diagnostic Codes Table    
Description    Conditions which Generate this Code    System Response    
E043(1) Low System Voltage     The battery voltage to the ECM is less than normal.     The code is logged.    
168-0 Electrical System Voltage high     The battery supply voltage is greater than 32 VDC for two seconds.
The engine's ECM has been powered for three seconds.
The engine is not being cranked.    
168-1 Electrical System Voltage low     The battery supply voltage is less than 9 VDC for two seconds.
The engine's ECM has been powered for three seconds.
The engine is not being cranked.    
168-2 Electrical System Voltage erratic, intermittent, or incorrect     The engine is running. The battery voltage falls below 9 VDC for at least .06 seconds. The voltage returns above 9 VDC.
or
Three voltage readings in the last seven seconds were below 9 VDC.    To reduce resistance in the wiring harness, there are two isolated power connections to the ECM. The connections must be complete in order to ensure proper engine operation. There may always be a constant power supply to the ECM when the locomotive engine is shutdown. In order to shut off the power to the ECM, the breaker for the ECM must be turned to the OFF position or the battery power needs to be disconnected.The engine will begin the start-up when the following conditions exist:
The ECM detects the input voltage at the input for the keyswitch.
The emergency stop switch is not activated.
The start/run/stop switch is in the RUN position.Note: Use an isolation transformer between the battery and the ECM in order to protect the ECM against a voltage spike or a ground loop.An emergency stop push button and a start/run/stop switch are provided in the junction box.The customer can install multiple start/run/stop switches(push button) and emergency stop push buttons. When the start/run/stop switches are activated the inputs to the ECM from the start/run/stop switches go low.When the emergency stop push button is activated, the emergency stop inputs float high. The fuel supply to the injectors will be cut off and the air shutoff relays will be activated.
Illustration 1 g01314139
Typical schematic
Illustration 2 g01258369
P1 ECM connector (P1-52) +Battery (P1-53) +Battery (P1-63) -Battery (P1-65) -Battery (P1-70) "ECM reset switch" (Keyswitch)
Illustration 3 g01258374
Connector "A" (Terminal 7) +Battery (Terminal 9) +Battery (Terminal 11) -Battery (Terminal 13) -Battery
Illustration 4 g01258377
Connector "B" (Terminal 13) "ECM reset switch" (Keyswitch)
Illustration 5 g01258378
Connector "F" (Terminal 2) -Battery (Terminal 6) +Battery
Illustration 6 g01234146
Location of ECM connectorsTest Step 1. Inspect Electrical Connectors and Wiring
Turn the breaker for the ECM to the OFF position.
Thoroughly inspect the ECM connectors J1/P1. Inspect all of the other connectors in the circuit. Refer to Troubleshooting, "Inspecting Electrical Connectors" for the proper procedure for inspecting