RING-BACKUP 1261978 - Caterpillar

System Operation Description:Use this procedure to troubleshoot any suspect problems with the electrical supply for the Electronic Control Module (ECM).Also, use this procedure to troubleshoot the 168-02 System Voltage intermittent/erratic.This procedure tests whether proper voltage is being supplied to the ECM.Unswitched battery voltage is supplied through the customer connector to the ECM at P1-48, P1-52, and P1-53. The negative battery is supplied to the ECM at P1-61, P1-63, and P1-65. The ECM receives the input from the keyswitch at P1-70 when the keyswitch is in the ON position or in the START position. When the ECM detects battery voltage at this input, the ECM will power up. When battery voltage is removed from this input, the ECM will power down.The cause of an intermittent power supply to the ECM can occur on either the positive side or on the negative side of the battery circuit. Both sides are routed from the ECM to the battery. The three connections for the unswitched +Battery should be routed through a dedicated protective device (circuit breaker).The engine ECM requires the keyswitch to be in the ON position in order to maintain communications with the electronic service tool.For intermittent problems such as intermittent shutdowns that could be caused by engine wiring, temporarily bypassing the engine wiring may be an effective means of determining the root cause. If the symptoms disappear with the bypass wiring, the engine wiring is the cause of the problem. A means of bypassing engine wiring is explained in this test procedure.
Illustration 1 g01128961
Schematic for ECM battery circuit
The connection of any electrical equipment and the disconnection of any electrical equipment may cause an explosion hazard which may result in injury or death. Do not connect any electrical equipment or disconnect any electrical equipment in an explosive atmosphere.
Test Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF position.
Illustration 2 g01146374
Left side engine view (typical example) (1) J1/P1 ECM connector
Illustration 3 g01146383
Left side engine view (typical example) (2) P61 Customer connector
Thoroughly inspect connectors (1) and (2). Also inspect the connections for the battery to the ECM. Inspect the connections from the keyswitch to the ECM. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 4 g01104383
P1 terminals that are associated with the electrical power supply (P1-44) Shutdown (P1-48) Unswitched +Battery (P1-52) Unswitched +Battery (P1-53) Unswitched +Battery (P1-61) −Battery (P1-63) −Battery (P1-65) −Battery (P1-70) Switched +Battery (keyswitch)
Illustration 5 g01129164
J61 and P61 terminals that are associated with the electrical power supply (1) +Battery (26) Switched +Battery (keyswitch) (27) Shutdown (31) +Battery (32) +Battery
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the electrical power supply.
Check the allen head screw on the ECM connector for the proper torque. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and wiring for abrasions and for pinch points from the battery to the ECM. Also, check the harness and wiring for abrasions and for pinch points from the keyswitch