RETAINER 2M1778 - Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with a sensor. Use this procedure if any one of the diagnostic codes in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table
J1939 Code CDL Code Code Description System Response
105-3 172-3 Engine Intake Manifold #1 Temperature : Voltage Above Normal The code is logged.
The ECM detects that the voltage is not in the acceptable range.
105-4 172-4 Engine Intake Manifold #1 Temperature : Voltage Below Normal The code is logged.
The ECM detects that the voltage is not in the acceptable range.
110-3 110-3 Engine Coolant Temperature Sensor : Voltage Above Normal The code is logged if the engine has been running for more than seven minutes and an open circuit has been detected.
110-4 110-4 Engine Coolant Temperature Sensor : Voltage Below Normal The code is logged. The ECM detects voltage that is not in the acceptable range.
175-3 175-3 Engine Oil Temperature 1 : Voltage Above Normal The code is logged.
The ECM detects that the voltage is not in the acceptable range.
175-4 175-4 Engine Oil Temperature 1 : Voltage Below Normal The code is logged.
The ECM detects that the voltage is not in the acceptable range.
1212-3 Engine Auxiliary Coolant Temperature : Voltage Above Normal The code is logged.
The ECM detects that the voltage is not in the acceptable range.
1212-4 Engine Auxiliary Coolant Temperature : Voltage Below Normal The code is logged.
The ECM detects that the voltage is not in the acceptable range.
4076-3 Engine Coolant Temperature #2 : Voltage Above Normal The code is logged.
The ECM detects that the voltage is not in the acceptable range.
4076-4 Engine Coolant Temperature #2 : Voltage Below Normal The code is logged.
The ECM detects that the voltage is not in the acceptable range.
Illustration 1 g03655622System OverviewThe sensor signal for the passive sensor is routed from the ECM to terminal 1 of each sensor connector. The sensor return for the passive sensors is routed to the ECM from terminal 2 of each sensor connector.Diagnostics on the Caterpillar Electronic Technician (ET)Wiggle Test - The Wiggle Test allows you to monitor the status of the signals from the sensors.For additional information regarding the Wiggle Test, refer to the documentation that accompanies the Cat ET software.
Illustration 2 g01155187
Terminal locations at the connector for the passive analog sensors
(Terminal 1) Sensor signal
(Terminal 2) Analog sensor return
Table 2
Troubleshooting Test Steps Values Results
1. Check for Diagnostic Trouble Codes
A. Connect to Caterpillar Electronic Technician (ET).
B. Turn the keyswitch to the ON position.
C. Access the "Active Diagnostic Code" screen on Cat ET.
Wait at least 30 seconds in order for the diagnostic codes to become active.
D. Look for these active codes or logged codes:
1. -3
2. -4
Codes
Result: A -3 diagnostic code is active.
Proceed to Test Step 2.
Result: A -4 diagnostic code is active.
Proceed to Test Step 3.
Result: For a diagnostic code that is logged but not currently active.
Proceed to Test Step 4.
2. Create a Short at the Sensor Connector
A. Turn the keyswitch to the OFF position.
B. Disconnect the