INSULATION AS 3116402 - Caterpillar

Illustration 10 g01435442
Terminal locations at the P5 connector on the terminal box that are for the circuit of the coolant pressure sensor on vee engines (P5-11) Shield (P5-21) Sensor return (P5-29) Signal for the engine coolant pressure (P5-37) +8 Volt supply
Turn the engine control switch to the OFF/RESET position. Switch the 16 amp circuit breaker for the ECM OFF.
Remove the signal wire for the coolant pressure sensor from the P5 connector at the terminal box.
Use a multimeter that is capable of measuring both the duty cycle and the frequency. Connect the multimeter between the signal wire from the P5 connector and the sensor's return wire at the P5 connector.
Switch the 16 amp circuit breaker for the ECM ON. Turn the engine control switch to the STOP position.
Measure the duty cycle and the frequency of the sensor. Record the values.Expected Result:The frequency is between 400 and 600 Hz.The duty cycle is between 5 and 95 percent.The frequency and the duty cycle are approximately equal to the values that were recorded for the previous Test Step.Results:
OK - The frequency and the duty cycle of the signal are within the specifications. The signal that is developed by the sensor is present at the terminal box. The engine harness appears to be OK. There may be a problem with a connector or with the harness inside the terminal box. Proceed to Test Step 6.
Not OK - The frequency or the duty cycle of the signal are not within the specifications. The signal that is developed by the sensor is not present at the terminal box. The signal wire in the engine harness has a problem. There may be a problem with a connector.Repair: Repair the harness or the connector, when possible. Replace the harness, if necessary.STOPTest Step 6. Check the Sensor's Signal at the ECM
Illustration 11 g01435431
Harness side of the ECM P2 connector (P2-65) +8 Volt supply (P2-66) Sensor return (P2-68) Signal for the engine coolant pressure
Turn the engine control switch to the OFF/RESET position. Switch the 16 amp circuit breaker for the ECM OFF.
Remove the signal wire from terminal P2-68 at ECM connector P2. Use a multimeter that is capable of measuring both the duty cycle and the frequency. Connect the multimeter between the signal wire from the P2 connector and the sensor's return wire at terminal P2-66.
Switch the 16 amp circuit breaker for the ECM ON. Turn the engine control switch to the STOP position.
Measure the frequency and the duty cycle of the signal.Expected Result:The frequency is between 400 and 600 Hz.The duty cycle is between 5 and 95 percent.The frequency and the duty cycle are approximately equal to the values that were previously recorded.Results:
OK - The frequency and the duty cycle of the signal are within the specifications. The signal that is developed by the sensor is present at the ECM. The connectors and the harness inside the terminal box appear to be OK. There may be a problem with the ECM.Repair: It is unlikely that the ECM has failed. Perform