950M and 962M Wheel Loaders Caterpillar

Condition Switch (Two Wire) - Test

Usage:

962M EJB

Implement ECM

The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the condition switch (two wire) circuits of the machine.

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Table 1
Implement ECM (MID 82)
DTC	Code Description	System Response
1195-3	Hydraulic Filter Bypass Switch: Voltage Above Normal	This code is triggered when the key switch is ON position and engine is not running. This code usually follows a bad hydraulic filter. Turn key switch OFF and then replace filter. After replacing filter turn key switch off without running the engine and see whether code goes away. Hydraulic filter bypass event is inhibited when hydraulic oil filter bypass switch is faulted and the system cannot determine whether hydraulic oil filter is bypassing or filtering. Debris may enter hydraulic system.

Possible causes for an FMI 3 Diagnostic code are:

The ground source is open.
A signal is permanently open.
The switch has failed.
The ECM has failed. An ECM failure is unlikely.

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Illustration 1	g03548348
Schematic of the Condition Switch (Two Wire) circuits

Note: The diagram above is a simplified schematic of the connections for the condition switch (two wire) circuits. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of the Electrical Schematic, UENR3117 for the complete schematic.

Diagnostic Trouble Code Procedure

Note: Prior to beginning this procedure, inspect the harness connectors that are involved in this circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure, and in good condition. If a problem with a connection is found, correct the problem and verify that the diagnostic code is active before performing a troubleshooting procedure. For sensors powered via the fuse panel, check the condition of the appropriate fuse before beginning the troubleshooting procedure.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Identify Active FMI Code Associated With Switch Circuit	Code present.	FMI 3 diagnostic code, proceed to Test Step 2.
Begin Process For FMI 3 Troubleshooting HERE
2. Check the Harness For an Open A. Turn key start switch and disconnect switch OFF. B. Disconnect the switch from the machine harness. C. Disconnect the J1 and J2 machine harness connector. D. At the machine harness connector for the switch, place a jumper wire between the signal contact and frame ground. E. At the machine harness connector for the ECM, measure the resistance between the signal contact and frame ground.	The resistance is less than 5 Ω.	OK - The resistance is less than 5 Ω. Proceed to Test Step 3. NOT OK - The resistance is greater than 5 K Ω. The circuit is open. Repair: Repair or replace the machine harness. Note: A resistance that is greater than 5 Ω but less than 5 K Ω indicates a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5 K Ω indicates an open in the circuit. Proceed to Test Step 6.
3. Check the Harness For an Open A. Turn key start switch and disconnect switch OFF. B. Disconnect the switch from the machine harness. C. Disconnect the J1 and J2 machine harness connector. D. At the machine harness connector for the switch, place a jumper wire between the signal contact and frame ground. E. At the machine harness connect for the ECM, measure the resistance between the signal contact and frame ground.	The resistance is less than 5 Ω.	OK - The resistance is less than 5 Ω. Proceed to Test Step 3. NOT OK - The resistance is greater than 5 K Ω. The circuit is open. Repair: Repair or replace the machine harness. Note: A resistance that is greater than 5 Ω but less than 5 K Ω indicates a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5 K Ω indicates an open in the circuit. Proceed to Test Step 6.
4. Check the Ground Source A. The keyswitch remains OFF. B. Reconnect the J1 and J2 machine harness connectors. C. Remove the jumper wire installed in the previous step. D. At the machine harness connector for the switch, measure resistance between the ground contact and frame ground.	The resistance is less than 5 Ω.	OK - The resistance is less than 5 Ω. Proceed to Test Step 4. NOT OK- The resistance greater than 5K Ω. Repair: The ground source is not good. Repair or replace the machine harness for the ground. Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. Proceed to Test Step 6.
5. Check the Switch. A. Turn the keyswitch ON. B. Monitor the status of the switch in Cat ET. C. At the machine harness connector for the switch, place a jumper wire from the signal contact to the ground contact. D. Move the jumper wire on and off the frame ground every 10 seconds and monitor the status of the switch in Cat ET.	The status of the switch goes from bypassing to not bypassing as the jumper wire is moved on and off frame ground.	OK - The status of the switch changes. Repair: The switch is faulty. Replace the switch. Proceed to Test Step 6. NOT OK - The switch status does not change. Proceed to test step 5. Proceed to Test Step 6.
6. Check If The Diagnostic Code Remains A. Inspect the harness connectors and clean the contacts of the harness connectors. B. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit. B. Reconnect all harness connectors. C. Turn key start switch and disconnect switch ON. D. Operate the machine. Check the status of the diagnostic code.	The diagnostic code is not active.	OK - The diagnostic code is not active. Repair: The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation. STOP NOT OK - The diagnostic code is still active. The ECM may have failed. Repair: Prior to replacing the ECM, contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, refer to Troubleshooting, "ECM - Replace" STOP