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| Illustration 1 | g01269997 |
Schematic of the Pattern Change Switch Circuit | |
This diagnostic code is associated with the Pattern Change Switch. This diagnostic code is recorded when inputs are either open or the inputs are shorted to the +battery circuit. This switch has three inputs to the ECM. Two inputs are normally open and one is normally closed. During proper operation in one switch position, one normally open contact will be closed and the other normally open contact will remain open. When the switch is actuated to the opposite position, the first contact will now be open and the other normally open contact will now be closed.
The possible causes for this diagnostic code are listed:
- The switch is disconnected.
- There is an open circuit in the wire harness.
- Short to the +battery circuit in the harness.
- The switch has failed.
System Response:
If the switch is faulted during operation, the last known value will be saved. If the switch is faulted at power up, the park brake will remain engaged and the implements will be locked out.
Note: Table 1 contains wire numbers and connector contacts. Use this information to troubleshoot the failed circuit.
| Switch Continuity | |||||
| Switch / CID | Switch State | Machine ECM Connector Contact No. | Switch Contact | Wire No. | Status |
| CID 1007 Pattern Change Switch | Not Actuated | J2-44 N/O (1) | N/O | J753-BU | O (2) |
| J2-45 N/C (3) | N/C | P797-GN | G (4) | ||
| J2-52 N/O | N/O | P796-OR | O | ||
| Actuated to "H" Position/#2 Alternate Pattern | J2-44 N/O | N/O | J753-BU | G | |
| J2-45 N/C | N/C | P797-GN | O | ||
| J2-52 N/O | N/O | P796-OR | O | ||
| Actuated to "#1 Cat/ISO" Position | J2-44 N/O | N/O | J753-BU | O | |
| J2-45 N/C | N/C | P797-GN | O | ||
| J2-52 N/O | N/O | P796-OR | G | ||
| ( 1 ) | N/O = Normally Open. |
| ( 2 ) | O = Open (no continuity to ground). |
| ( 3 ) | N/C = Normally Closed. |
| ( 4 ) | G = Grounded (continuity to ground). |
Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code is corrected.
Ensure that the diagnostic code is active.
Test Step 1. CHECK FOR OPEN CIRCUIT
- Turn the keyswitch to the OFF position.
- Verify that the Pattern Change switch is connected.
- Disconnect the harness from the ECM.
- Activate the switch. At the harness connector for the ECM, check the continuity to ground of the normally closed contact and the normally open contacts.
Expected Result:
The continuity check does not agree with Table 1.
Results:
- YES - The continuity check does not agree with the preceding table. Proceed to Test Step 2.
- NO - The continuity agrees with the values in the preceding table. Proceed to Test Step 3.
Test Step 2. CHECK THE SWITCH
- Disconnect the harness from the switch.
- At the harness connector for the ECM, check the continuity to ground of the normally closed contact and the normally open contact. Activate the switch when this check is being performed.
Expected Result:
The continuity check does not agree with the values in Table 1.
Results:
- YES - The continuity check does not agree with the preceding table.
Repair: The switch has failed. Repair the switch or replace the switch.
STOP
- NO - The continuity check agrees with the preceding table.
Repair: The harness has failed. Repair the harness or replace the harness.
STOP
Test Step 3. CHECK FOR A SHORT TO +BATTERY
- Check the continuity from each switch wire at the harness connector for the ECM to contact J1-39 (Wire 128-RD).
Results:
- YES - Continuity exists between the source of battery voltage and the switch circuit.
Repair: The harness has failed. Repair the harness or replace the harness.
STOP
- NO - Continuity does not exist between the source of battery voltage and the switch circuit. The harness circuit is correct.
Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this troubleshooting procedure again. 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 ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
STOP