SWITCH AS-TEMPERATURE 7E9425 - Caterpillar

System Operation Description:The Electronic Control Module (ECM) provides the engine speed/timing sensor with 12.5 1.0 VDC. The engine speed/timing sensor provides a pulse signal to the ECM. The signal is created as the timing reference gear rotates past the pickup of the engine speed/timing sensor. The timing reference gear is mounted on the rear of the left camshaft. A unique tooth pattern on the timing reference gear allows the ECM to determine the crankshaft position, rotation, and rpm.The engine speed/timing sensor generates a pulse signal to the ECM as each tooth passes the sensor. The ECM counts the pulses in order to determine the engine rpm. The ECM memorizes the pattern of the pulses. The ECM compares that pattern to a standard pattern in order to determine the crankshaft position. The ECM uses this information to determine the No. 1 cylinder. The ECM then triggers each unit injector to fire in the correct firing order and at the correct time. The actual timing and duration of each injection is determined by the ECM. The ECM uses engine rpm and engine load to determine the timing and duration of injection. The loss of the signal from the engine speed/timing sensor generates an alert on the Caterpillar Electronic Technician (ET). The loss of the signal from the engine speed/timing sensor triggers the termination of the signals to the fuel injectors by the ECM.Note: If the engine timing gear is installed backward, the diagnostic code 190-08 will be generated. If this code is active, the ECM will not fire the injectors. You may refer to the diagnostic procedure Troubleshooting, "Engine Monitoring System" in order to determine if there are any parameters that are affecting engine operation.
Illustration 1 g00594171
Typical exampleTest Step 1. Check for Connector Damage.
Turn the Engine Control Switch (ECS) to the OFF/RESET position.
Thoroughly inspect the ECM connector J1/P1 and the machine connector 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 ECM connector (allen head screw) for the proper torque of 2.25 0.25 N m (20 2 lb in).
Check the machine connector (allen head screw) for the proper torque of 2.25 0.25 N m (20 2 lb in).
Check the harness and the wiring for abrasion and for pinch points.Expected Result:The connectors and wiring are free of the following problems: damage, corrosion, abrasion and incorrect attachment.Results:
OK - The connectors and wiring are okay. Proceed to Test Step 2.
Not OK - The connectors and/or wiring are not okay.Repair: Repair the connectors and/or wiring or replace the connectors and/or wiring.STOPTest Step 2. Check for an "ACTIVE" Diagnostic Code.
Connect Cat ET to the service tool connector. Start Cat ET.
Turn the ECS to the STOP position. The engine should be off.
Access the logged diagnostic codes on Cat ET.Expected Result:The Cat ET screen indicates one of the following diagnostic