ROD 2394415 - Caterpillar

System Operation Description:The engine's Electronic Control Module (ECM) receives 24 VDC from the battery. Electrical power comes from the 20 amp breaker for the ECM to the normally close contacts of relay "R2A". The electrical power to the ECM from the normally closed contact of relay "R2A" is on wire C150 and on wire 150. The wire C150 goes to pin P1-53 of ECM connector J1/P1. The wire 150 goes to pin P1- 52 of ECM connector J1/P1. The −Battery is applied to pin P1-63 and pin P1-65 of ECM connector J1/P1. The wire numbers for the −Battery are wire D229 and wire 229 . The Engine Control Switch (ECS) sends a signal to pin P1-70 of the ECM when the ECS is in the following positions: REMOTE, STOP and START. When the ECM senses battery voltage on pin P1-70 of the ECM, the ECM will power up. When the ECS is in the OFF/RESET position, voltage is not present on P1-70 and the ECM will power down.When the emergency stop switch is activated, relays"R4" and "R4A" energize. Electrical power from relay "R4A" is routed to terminal 3 of the timer. When 24 VDC is applied to terminal 3 of the timer, the timer activates for 2.5 seconds. The timer outputs 24 VDC to the coil of the air shutoff switch (ASOS). The timer also outputs 24 VDC to the diode assembly and to the coils of relay "R3A" and relay "R3". When relay "R3A" is energized, power is applied to the coil of relay "R2A". When relay "R2A" is energized, the normally closed contacts of relay "R2A" open. This removes electrical power to the ECM.In order to restart the engine, the operator must correct the cause of the emergency stop condition. The ECS must be turned to the OFF/RESET position for three seconds. This resets the ECM and the air shutoff timer. In addition to turning the ECS to the OFF/RESET position, the operator must manually open the air shutoff valves before starting the engine.The presence of two +Battery connections and two −Battery connections to the ECM reduce harness resistance. All of these connections must be complete in order to ensure proper engine operation.
Illustration 1 g01199226
Typical exampleNote: If a remote START switch is installed, the remote START switch must be in the STOP position for this test. Test Step 1. Check for Connector Damage
Turn the ECS to the OFF/RESET position.
Turn the circuit breaker for the battery to the OFF position.
Verify that the circuit breakers are not tripped.
Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors. Refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.
Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points.Expected