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| Illustration 1 | g01240944 |
Grapple Open/Close switch connections | |
This diagnostic code is recorded when the ECM reads the voltage from the one of the grapple open/close switches as erratic or intermittent. The two switches are switch to ground type inputs to the ECM. The ECM expects one of the three switch inputs to be grounded at all times.
Possible causes of the diagnostic code is listed:
- The common ground circuit is not correct.
- One of the switches is not working correctly.
- There is a grounded wire in one of the switch circuits.
- There is a short to a +battery source in one of the switch circuits.
- The ECM has failed. This is unlikely.
The following table indicates the switch states for the Open and Close positions.
| Grapple Open/Close Switch Circuit Continuity (1) | |||||
| ECM Connector J2 | Connector (2) Contact No. of Joystick Handle | Wire No. | OPEN Position | HOLD Position | CLOSE Position |
| 32 | 3 | C906-PU | X | O | O |
| 59 | 5 | F839-OR | O | X | O |
| 33 | 4 | C907-WH | O | O | X |
| ( 1 ) | "O" = Open - no continuity to ground. "X" = Closed - continuity to ground |
| ( 2 ) | Ground is contact No. 1 wire 202-BK of the grapple control joystick handle connector. |
Test Step 1. CHECK THE GROUND CIRCUIT
- Turn the disconnect switch and the key switch to the OFF position.
- Disconnect the grapple control joystick from the machine harness connector.
- At the machine harness connector for the grapple control joystick handle, measure the resistance between contact 1 (wire 202-BK) and frame ground.
Expected Result:
The resistance measurement is less than 5 ohms.
Results:
- OK - The resistance measurement is less than 5 ohms. Proceed to Test Step 2.
- NOT OK - The resistance measurement is greater than 5 ohms. The ground circuit for the grapple control handle is not correct.
Repair: There is an open or bad connection in wire 202-BK between the ECM and the grapple control handle. Refer to the complete machine Electrical System Schematic. Check the connectors and splices that are in the ground circuit for loose or corroded connections. Repair the machine harness or replace the machine harness.
STOP
Test Step 2. CHECK THE SWITCH OPERATION
The disconnect switch and the key switch remain in the OFF position.
- At the grapple control joystick connector, check the continuity between the common contact 1 (ground) and each of the three contacts for the Open/Close switches. Check continuity from common contact 1 (ground) to each switch connector contact when the switch is depressed and when the switch is not depressed. Refer to the continuity table and the connection diagram above for the correct contact continuity.
Expected Result:
The continuity checks between common contact 1 to the other switch contacts are correct.
Results:
- OK - The continuity checks between common contact 1 to the other switch contacts are correct. The switches are operating correctly. Proceed to Test Step 3.
- NOT OK - The continuity checks between common contact 1 to the other switch contacts are not correct according to the table. One of the switches is not working correctly switch.
Repair: Replace the switch that is not working correctly.
STOP
Test Step 3. CHECK THE INPUT CIRCUITS FOR A SHORT TO GROUND
The disconnect switch and the key switch remain in the OFF position. The grapple control handle remains disconnected from the machine harness connector.
- At the machine harness connector for the grapple control joystick handle, measure the resistance between contact 3 (wire C906-PU) and frame ground.
- At the machine harness connector for the grapple control joystick handle, measure the resistance between contact 4 (wire C907-WH) and frame ground.
- At the machine harness connector for the grapple control joystick handle, measure the resistance between contact 5 (wire F839-OR) and frame ground.
Expected Result:
Each resistance measurement is greater than 5000 ohms.
Results:
- OK - Each resistance measurement is greater than 5000 ohms. Proceed to Test Step 4.
- NOT OK - One or more of the resistance measurements is less than 5000 ohms. There is short to a ground source in the machine harness.
Repair: The short is between the switch input circuit that measured the low resistance and a machine ground source. Refer to the complete machine Electrical System Schematic. Check the wiring harness for signs of abrasion with the machine frame. Repair the machine harness or replace the machine harness.
STOP
Test Step 4. CHECK THE INPUT CIRCUITS FOR A SHORT TO +BATTERY
The key start switch and the disconnect switch remain in the OFF position. The grapple control handle remains disconnected from the machine harness connector.
- Disconnect the machine harness connectors J1 and J2 from the ECM.
- At the machine harness J2 connector, measure the resistance from contact J2-32 (wire C906-PU) to all + battery (wire 170-RD) contacts that are used on the ECM connectors. The + battery contacts are J2-31, J2-38, J2-39 and J2-47.
- Repeat the above Step with the two other switch input circuits at contact J2-33 (wire C907-WH) and J2-59 (wire F839-OR).
Expected Result:
Each resistance measurement is greater than 5000 ohms.
Results:
- OK - Each resistance measurement is greater than 5000 ohms. The switch input circuits are not shorted in the harness. Proceed to Test Step 5.
- NOT OK - One or more of the resistance measurements is less than 5000 ohms.
Repair: The switch input circuit with the low resistance measurement is shorted to a +battery source in the machine harness. Refer to the complete machine Electrical System Schematic. Check the connectors that are in the involved circuits. Ensure that all connections points for the circuits that show a short are clean, secure and in good condition. Repair the machine harness or replace the machine harness.
STOP
Test Step 5. CHECK THE STATUS OF THE DIAGNOSTIC CODE
- Inspect the contacts and clean the contacts of the any harness connectors that are disconnected.
- Reconnect all harness connectors.
- Turn the disconnect switch and the key start switch to the ON position.
- Operate the machine.
- Determine if the CID 0450 FMI 02 diagnostic code is active.
Expected Result:
The CID 0450 FMI 02 diagnostic code is active.
Results:
- YES - The CID 0450 FMI 02 diagnostic code is active. The problem has not been corrected. The ECM may be faulty.
Repair: Repeat this procedure. Use the Caterpillar Electronic Technician (ET) service tool, if available, in order to perform a "Wiggle Test" on the sensor circuit in the machine wiring harness. The wiggle test can detect momentary or intermittent shorts or opens in the machine wiring harness.If a problem is not found in the machine harness, replace the rotation switches. If the problem is still present after replacement of the switches, the ECM may be faulty.If the cause of the problem is not found, the ECM may be faulty. Prior to replacing an ECM, always contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the cause of the diagnostic code is not found, replace the Machine ECM. Refer to Troubleshooting, "Electronic Control Module (ECM) - Replace".
STOP
- NO - The CID 0450 FMI 02 diagnostic code is not active. The problem does not exist at this time.
Repair: The initial diagnostic code was probably cause by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.
STOP