AccuGrade® Laser (CB420) Caterpillar

Illustration 1	g01160267

This diagnostic code is recorded when the ECM records an erratic signal or an intermittent signal from the Left Grade Offset Switch.

The possible causes for this diagnostic code are listed:

• The switch has failed.

• The signal circuit is open.

• A signal circuit is shorted to the +battery circuit.

• The signal circuit is shorted to ground.

• The signal circuits may be shorted together.

• The ECM has failed.

Note: Ensure that CID 2261 FMI 02 is active and that the diagnostic code indicator is active.

Test Step 1. CHECK THE OPERATION OF THE SWITCH.

1. Turn the key start switch and the disconnect switch to the OFF position.

2. Disconnect the machine harness connector from the Switch.
   Show/hide table

   Table 1

   Contacts	Switch State
   	Increment	Neutral	Decrement
   Contacts 1 to 2	Greater than 5000 ohms	Greater than 5000 ohms	Less than 5 ohms
   Contacts 2 to 3	Less than 5 ohms	Greater than 5000 ohms	Greater than 5000 ohms
   Contacts 2 to 4	Greater than 5000 ohms	Less than 5 ohms	Greater than 5000 ohms

3. Measure the resistance between the contact points on the connector listed in the table above. Note the resistance values.

Expected Result:

The measurements agree with the values that are listed in Table 1.

Results:

• YES - The resistances that were measured agree with the expected measurements listed in the table. Proceed to Test Step 2.

• NO - The resistance measurements do not reflect the expected measurements that are listed in the table. The switch has failed.

  Repair: Replace the switch.

  STOP

Test Step 2. CHECK FOR A SHORTED HARNESS.

1. The Left Grade Offset Switch remains disconnected.

2. Turn the disconnect switch and the key start switch to the OFF position.

3. Disconnect the harness connector (J1) from the ECM.

4. At the harness connector for the ECM (J1), measure the resistance between contact J1-34 (wire Y933-YL) and ALL other J1 connector contacts.

5. At the harness connector for the ECM (J1), measure the resistance between contact J1-35 (wire Y934-WH) and ALL other J1 connector contacts.

6. At the harness connector for the ECM (J1), measure the resistance between contact J1-40 (wire Y938-PK) and ALL other J1 connector contacts.

7. At the harness connector for the ECM (J1), measure the resistance between contact J1-56 (wire C209-BK) and ALL other J1 connector contacts.

Expected Result:

The resistance is greater than 5000 Ohms.

Results:

• YES - The resistance is greater than 5000 Ohms. The harness resistance is correct. Proceed to Test Step 3.

• NO - Resistance is less than 5000 Ohms.

  Repair: The harness has failed. Repair the harness or replace the harness.

  STOP

Test Step 3. CHECK FOR AN OPEN HARNESS.

1. The Left Grade Offset Switch remains disconnected from the harness.

2. The key start switch and the disconnect switch are in the OFF position.

3. At the harness connector for the Left Grade Offset Switch, place a jumper wire between the following contacts:
   • Contact 1 (wire Y933-YL) and Contact 2 (wire C209-BK)

   • Contact 3 (wire Y934-WH) and contact 4 (wire Y936-PK)

4. The J1 connectors remain disconnected from the ECM.

5. At the harness connector for the ECM, measure the resistance between contact J1-34 (wire Y933-YL) and J1-56 (wire C209-BK). Make a note of the resistance that was measured.

6. At the harness connector for the ECM, measure the resistance between contact J1-35 (wire Y934-WH) and J1-42 (wire Y936-PK). Make a note of the resistance that was measured.

Expected Result:

The resistance is less than 5 Ohms for all of the measurements.

Results:

• YES - The resistance is less than 5 Ohms for all of the measurements. Proceed to Test Step 4.

• NO - Resistance is greater than 5000 Ohms for one or more of the measurements.

  Repair: The harness has failed. Repair the harness or replace the harness.

  STOP

Test Step 4. CHECK THE ECM.

1. Reconnect the all connectors to the Implement/Valve ECM.

2. Turn the disconnect switch and the key start switch to the ON position.

3. The harness remains disconnected from the switch.

4. At the harness connector for the switch, measure the voltage between the each of the following contacts:
   • Contact 2 (wire C209-BK) and 1 (wire Y933-YL)

   • Contact 2 (wire C209-BK) and 3 (wire Y934-WH)

   • Contact 2 (wire C209-BK) and 4 (wire Y936-PK)

Expected Result:

The voltage measures approximately 12.0 ± 0.5 DCV.

Results:

• YES - The voltage measures approximately 12.0 ± 0.5 DCV. Proceed to Test Step 5.

• NO - The voltage is NOT approximately 12.0 ± 0.5 DCV.

  Repair: The voltage from the ECM is incorrect. It is unlikely that the ECM has failed. Exit this procedure and perform this troubleshooting procedure again. If the diagnostic code is not found replace the ECM. See Testing and Adjusting, "Module - Replace".

  STOP

Test Step 5. CHECK IF THE DIAGNOSTIC CODE IS STILL ACTIVE.

1. Inspect the contacts and clean the contacts of the harness connectors.

2. Reconnect all harness connectors.

3. Turn the disconnect switch and the key start switch to the ON position.

4. Operate the machine.

5. Determine if the CID 2261 FMI 02 is active.

Expected Result:

The CID 2261 FMI 02 is no longer active.

Results:

• YES - The CID 2261 FMI 02 is not active. The problem does not exist at this time.

  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

• NO - The CID 2261 FMI 02 is active. The problem has not been corrected. The ECM may have failed.

  Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECM. See Testing and Adjusting, "Module - Replace".

  STOP