950M and 962M Wheel Loaders Caterpillar

Operator Control Switch (Switch to Battery) - Test

Usage:

962M EJB

Implement ECM

The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the operator control switch (switch to battery) circuits of the machine.

Show/hide table

Table 1
Implement ECM (MID 82)
DTC	Code Description	System Response
1529-3	Quick Coupler Switch: Voltage Above Normal	Load sense solenoid is de-energized, the operator will not be able to change the work tool. This code is triggered when both pins are open.
1529-4	Quick Coupler Switch: Voltage Below Normal	Load sense solenoid is de-energized, the operator will not be able to change the work tool. This code is triggered when both pins are grounded.

Possible causes for an FMI 3 Diagnostic code are:

Both signal contacts are shorted to battery.
The switch has failed.
The ECM has failed. A failure of the Implement ECM is unlikely.

Possible causes for an FMI 4 Diagnostic code are:

Both signal contacts are open.
The switch has failed.
The ECM has failed. A failure of the Implement ECM is unlikely.

Show/hide table




Illustration 1	g03592702
Schematic of the Operator Control Switch (Switch to Battery) circuits

Note: The diagram above is a simplified schematic of the connections for the operator control switch (switch to battery) 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.

Show/hide table

Table 2
Switch Operation For the Quick Coupler Switch (CID 1529)
Contacts	Switch State	Continuity
1, 2	Engage	Yes
1, 2	Retract	No
2, 3	Engage	No
2, 3	Retract	Yes

Transmission ECM

The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the operator control switch (switch to battery) circuits of the machine.

Show/hide table

Table 3
Transmission ECM (MID 81)
DTC	Code Description	System Response
1834-2	Ignition Key Switch: Data Erratic, Intermittent, or Incorrect	If equipped, the warning lamp will come on. The diagnostic code will be logged. The ECM will stop energizing the injector solenoids. The engine will shut down.

Note: This code can be generated by rapidly cycling the keyswitch. Some control modules on the application may require this action in order to prompt flash codes. If this occurs, clear the logged diagnostic codes in order to prevent future confusion or an incorrect diagnosis

Possible causes for an FMI 2 Diagnostic code are:

Wire is shorted to the +Battery.
An open circuit exists.
The ECM has failed. A failure of the ECM is unlikely.

Show/hide table




Illustration 2	g03646397
Schematic of the Operator Control Switch (Switch to Battery) circuits

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.

Show/hide table

Table 4
Troubleshooting Test Steps	Values	Results
1. Identify Active FMI Code Associated With Sensor Circuit	Code present.	FMI 2 diagnostic code, proceed to Test Step 2. FMI 3 diagnostic code, proceed to Test Step 3. FMI 4 diagnostic code, proceed to Test Step 5.
Begin Process For FMI 2 Troubleshooting HERE
2. Check The Harness A. Turn the key start switch and disconnect switch OFF. B. Inspect the harness. C. Check for the proper mating D. Check the exposed wires for nicks and abrasions. E. Check for moisture, dirt, or corrosion. F. Check the pin/socket for a proper fit.	The harness appears to be correct.	OK - The harness appears to be correct. Proceed to Test Step 11. NOT OK - The harness appears to be damaged. Repair: Repair the machine harness or replace the machine harness. Proceed to Test Step 11.
Begin Process For FMI 3 Troubleshooting HERE
3. Check The Circuit For A Short A. Turn the key start switch and disconnect switch OFF. B. Disconnect the switch from the machine harness. C. Disconnect the J1 and J2 machine harness connections from the Implement ECM. D. At the machine harness connector for the ECM, one at a time, measure the resistance between each of the signal contacts to every other contact used in the J1 and J2 machine harness connectors.	The resistance is greater than 5 K Ω.	OK - The resistance is correct. Proceed to Test Step 4. NOT OK - The resistance check is not correct. Repair: There is a short in the signal circuits of the machine harness. Repair or replace the machine harness. Proceed to Test Step 11.
4. Check the Operation of the Switch. A. The key start switch and disconnect switch remain OFF. B. Reconnect all harness connectors. C. Check the operation of the switch. Refer to the table for the suspected faulty switch at the beginning of this procedure for switch operation.	The switch operates correctly.	OK - The switch is operating correctly. Proceed to Test Step 11. NOT OK - The switch is not operating correctly. The switch has failed Repair: Replace the switch. Proceed to Test Step 11.
Begin Process For FMI 4 Troubleshooting HERE
5. 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 contacts. E. At the machine harness connect for the ECM, measure the resistance between the signal contacts.	The resistance is less than 5 Ω.	OK - The circuit is correct. Proceed to Test Step 6. NOT OK - The resistance is greater than 5K ohms . The circuit is open. Repair: Repair or replace the machine harness. Note: A resistance that is greater than 5 Ω but less than 5K ohms indicates a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω indicates an open in the circuit. Proceed to Test Step 11.
6. Check Diodes for the Circuit. A. The key start switch remains OFF. B. Disconnect the diodes in the circuit. C. At the diode, place the positive multimeter lead on pin 1 and the negative lead on pin 2. D. Measure resistance through the circuit.	The resistance is greater than 5K Ω.	OK - The resistance is greater than 5K ohms. Proceed to Test Step 7. NOT OK - The resistance is less than 5 ohms. Repair: Replace the diode, then replace the quick coupler fuse. Proceed to Test Step 11.
7. Check The Circuit For A Short A. Turn the key start switch and disconnect switch OFF. B. Disconnect the switch from the machine harness. C. Disconnect the J1 and J2 machine harness connections from the Implement ECM. C. At the machine harness connector for the ECM, one at a time, measure the resistance between each of the signal contacts to every other contact used in the J1 and J2 machine harness connectors.	The resistance is greater than 5K Ω.	OK - The resistance is correct. Proceed to Test Step 8. NOT OK - The resistance check is not correct. Repair: There is a short in the signal circuits of the machine harness. Repair or replace the machine harness. Proceed to Test Step 11.
8. Check the Battery Source for the Switch. A. Reconnect all harness connections. B. Turn the key start switch and disconnect switch to the ON position. C. At the switch, measure voltage between the battery contact and frame ground.	Voltage is 24 ± .5V	OK - The voltage is correct. Proceed to Test Step 10. NOT OK - The voltage is not correct. Proceed to Test Step 9.
9. Check the Fuse. A. Turn the key start switch and the disconnect switch to the OFF position. B. Check the fuse for the switch.	The fuse is good.	OK - The fuse is good. Proceed to Test Step 11. Repair: The harness for the battery source has failed. Repair or replace the machine harness. NOT OK - The fuse has failed. Replace the fuse. Proceed to Test Step 11.
10. Check the Operation of the Switch. A. Turn the key start switch and disconnect switch to the OFF position . B. Reinstall the signal wire removed in the previous step. C. Check the operation of the switch. Refer to the table for the suspected faulty switch at the beginning of this procedure for switch operation.	The switch operates correctly.	OK - The switch is operating correctly. Return the machine to service and monitor the situation. Proceed to Test Step 11. NOT OK - The switch is not operating correctly. The switch has failed Repair: Replace the switch. Proceed to Test Step 11.
11. Check If The Diagnostic Code Remains. A. Turn the key start switch and the disconnect switch ON. B. Clear all diagnostic codes. C. Operate the machine. D. Stop machine and engage the safety lock lever. E. Check if the diagnostic code for the sensor is active.	The code for the sensor is NO longer present.	OK - The diagnostic code does not exist at this time. The initial diagnostic code may have been caused by a poor electrical connection or a short at one of the harness connections. Resume machine operation. STOP NOT OK - The diagnostic trouble code has not been corrected. Repair: Recheck the circuit and perform this procedure again. If the diagnostic code is still active, replace the sensor. If replacing the sensor does not correct the problem, the ECM may require replacement. Prior to replacing the ECM, always contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. See Troubleshooting, "ECM - Replace". STOP