MANIFOLD 7L4096 - Caterpillar

Table 1
Temperature Switch Connections    
Temp. Switch    ECM Contact    Wire No.    
Left Extender     J2-14     P851-WH    
Left Main     J2-23     P852-PU    
Right Extender     J2-38     P854-BU    
Right Main     J2-35     P853-YL    
Return     J1-15     P203-GN    
Turn the key start switch to the OFF position.
Turn the burner system switch to the OFF position and move all of the burner mode switches to the OFF position.
While the burner is cold, disconnect the ECM connectors J1 and J2. At the harness connector for the ECM, check the resistance between the suspect temperature switch input contact and the return contact J1-15 (wire P203-GN).Expected Result:The resistance measurement should be 5 ohms or less.Results:
OK - The resistance measurement is 5 ohms or less.Repair: The switch is correct at the cold temperature. If the switch is not opening the contacts at 154.4 °C (310.0 °F), the ECM will activate a "Failure to Reach Temperature" event code. If this occurs, perform the "Temperature Not High Enough" procedure in the "Diagnostic Code Procedures" section of this manual. Stop.
NOT OK - The resistance measurement is greater than 5 ohms.Repair: Either the switch or the machine harness is not correct. Proceed to Step 2.Test Step 2. Check Machine Harness
The key switch remains OFF.
Disconnect the temperature switch from the machine harness.
Measure the resistance between contact 1 and contact 2 on the temperature switch connector.Expected Result:The resistance measurement should be 5 ohms or less.Results:
OK - The resistance measurement is 5 ohms or less.Repair: The temperature switch is correct. The machine harness is open between ECM connector contact J1-15 and the involved temperature switch ECM input contact. Repair the machine harness or replace the machine harness. Stop.
NOT OK - The resistance measurement is greater than 5 ohms.Repair: The temperature switch is malfunctioning. Replace the temperature switch. If the temperature switch can not be replaced immediately, the burner can be operated in the MANUAL mode. When operating the burner in the MANUAL mode, the operator MUST ensure that the burner ignites. In Manual mode, the fuel will continue to be sprayed into the burner chamber regardless of whether the burner has ignited or not. Replace the temperature switch at the earliest possible time. Stop.