C7.1 Industrial Engine and Generator Set Caterpillar

This procedure covers the following diagnostic code:

Use this procedure if the electronic service tool will not communicate with the ECM through the data link.

The following background information is related to this procedure:

The data link is the standard data link that is used by the ECM in order to communicate with the electronic service tool.

The ECM provides multiple connections for the data link. The technician must ensure that the correct connector is being tested. The connection that is used is dependent on the application.

If the diagnostic connector is on the engine, the positive data link signal will be from P2:28 to pin "D" of the diagnostic connector. The negative data link signal will be from P2:20 to pin "E" of the diagnostic connector.

If the diagnostic connector is off the engine, the positive data link signal will be from P1:8 to pin "D" of the diagnostic connector. The negative data link signal will be from P1:9 to pin "E" of the diagnostic connector.

The following information refers to the pin number. Ensure that the correct connector is used.

Communication

The electronic service tool may indicate the following error message:

The version of the ECM is not recognized and the integrity of the changed parameters and displayed data is not guaranteed.

This message will indicate that the version of the software that is in the electronic service tool is obsolete. Install the latest version of the software for the electronic service tool in order to rectify the fault.

Illustration 1	g02090374
Schematic of the diagnostic connector and the data link connector for an engine mounted diagnostic connector

Illustration 2	g02090334
Schematic of the diagnostic connector and the data link connector for a diagnostic connector that is mounted off engine

Illustration 3	g02028056
Typical view of the P1 pin locations for the diagnostic connector (8) Data link + (9) Data link -

Illustration 4	g02090413
Typical view of the P2 pin locations for the diagnostic connector (20) Data link - (28) Data link + (53) Voltage supply (diagnostic connector) (54) Return (diagnostic connector)

Test Step 1. Inspect Electrical Connectors and Wiring

1. Thoroughly inspect the following electrical connectors:

   • P1/J1 ECM connector

   • P2/J2 ECM connector

   • The connection for the diagnostic connector

   Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

2. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors that are associated with the data link.

3. Check the screw for the ECM connectors for correct torque of 6 N·m (53 lb in).

4. Check the harness for abrasion and pinch points from the wires that connect the diagnostic connector to the ECM.

Expected Result:

All connectors, pins, and sockets are correctly connected and/or inserted. The harness should be free of corrosion, abrasion and/or pinch points.

Results:

• OK - Proceed to Test Step 2.

• Not OK -

  Repair: Perform the following repair:

  Repair the connectors and/or the harness, or replace the connectors and/or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are correctly connected.

  Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP

Test Step 2. Determine the Type of Fault in the Data Link

1. Connect the electronic service tool to the diagnostic connector that is on the engine harness or on the application.

2. Turn the keyswitch to the ON position.

Expected Result:

The power lamp should illuminate on the communications adapter. The power lamp on the communications adapter may illuminate when the keyswitch is in any position.

Results:

• OK - The communications adapter is currently receiving the correct voltage. Proceed to Test Step 5.

• Not OK - The communications adapter is not receiving the correct voltage. Proceed to Test Step 3.

Test Step 3. Check the Battery Voltage at the Diagnostic Connector

1. Turn the keyswitch to the ON position.

2. Use a multimeter in order to measure the voltage from pin A (battery+) and pin B (ground) of the diagnostic connector.

Expected Result:

The voltage is between 22.0 VDC and 27.0 VDC for a 24 V system. The voltage is between 11.0 VDC and 13.5 VDC for a 12 V system.

Results:

• The diagnostic connector is currently receiving the correct voltage. - Proceed to Test Step 5.

• The diagnostic connector is not receiving the correct voltage. - Proceed to Test Step 4.

Test Step 4. Bypass the Wiring for the Diagnostic Connector

Illustration 5	g01241517
Typical view of the diagnostic connector from the wire side (A) Switched battery + (B) Battery ground (GND) (D) Data link + (E) Data link -

1. Disconnect the wires from pin A and pin B of the diagnostic connector.

2. If the diagnostic connector is mounted on the engine, perform the following steps:

   1. Disconnect the wires from P2:53 and P2:54.

   2. Fabricate a jumper wire in order to connect pin A of the diagnostic connector to P2:53.

   3. Fabricate a jumper wire in order to connect pin B of the diagnostic connector to P2:54.

3. If the diagnostic connector is mounted off the engine, perform the following step:

   1. Fabricate a jumper wire in order to connect pin "A" of the diagnostic connector to battery+ and pin "B" to the battery-.

4. Connect the electronic service tool to the diagnostic connector that is on the engine harness or on the application.

5. Turn the keyswitch to the ON position.

Expected Result:

The power lamp should illuminate on the communications adapter. The power lamp on the communications adapter may illuminate when the keyswitch is in any position.

Results:

• The power lamp is illuminated - The fault is in the harness.

  Repair: Repair the faulty harness or replace the faulty harness.

  Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP

• The power lamp is not illuminated. -

  Repair:

  Proceed to Test Step 6.

Test Step 5. Check the Data Link Connections

1. Turn the keyswitch to the OFF position.

2. Disconnect the communications adapter from the diagnostic connector.

3. If the diagnostic connector is installed on the application, disconnect connector P1 from the ECM. Check the resistance between P1:8 and pin "D" on the diagnostic connector. If the diagnostic connector is installed on the engine, disconnect P2 from the ECM. Check the resistance between P2:28 and pin "D" on the diagnostic connector.

4. If the diagnostic connector is installed on the application, check the resistance between P1:9 and pin "E" on the diagnostic connector. If the diagnostic connector is installed on the engine, check the resistance between P2:20 and pin "E" on the diagnostic connector.

Results:

• The resistance is less than 10 Ohms - Proceed to Test Step 6.

• The resistance is greater than 10 Ohms. -

  Repair: Perform the following repair:

  Repair the connectors and/or the harness, or replace the connectors and/or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are correctly connected.

  Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP

Test Step 6. Change the Electronic Service Tool Components

1. If another electronic engine is available, connect the electronic service tool to the other engine. Ensure that the same cables are used.

2. Turn the keyswitch to the ON position. Determine if the electronic service tool operates correctly on the other engine.

3. If another engine is not available, obtain a replacement communications adapter and a replacement set of cables. Ensure that the set of cables for the electronic service tool are a complete set.

4. Install the replacement communications adapter and the set of cables for the electronic service tool and connect to the diagnostic connector.

5. Turn the keyswitch to the ON position.

6. If changing the communications adapter or the cables allows the electronic service tool to operate correctly, perform the following procedure:

   1. Replace the components from the new set of cables with components from the original set of cables. Replace one component at a time.

   2. Apply power to the electronic service tool after each of the components is replaced. Use this method to find the faulty component.

7. If changing the cables does not allow the electronic service tool to operate correctly, connect another electronic service tool.

8. Turn the keyswitch to the ON position.

Results:

• The original electronic service tool works on another engine - Proceed to Test Step 7.

• A different electronic service tool works on the original engine while the engine is being tested. -

  Repair: Send the faulty electronic service tool for repairs.

  STOP

Test Step 7. Connect an Electronic Service Tool and the ECM to another Battery

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Batteries give off flammable fumes which can explode. To avoid injury or death, do not strike a match, cause a spark, or smoke in the vicinity of a battery.

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NOTICE
Do not connect the bypass harness to the battery until the in-line fuse has been removed from the Battery+ line. If the fuse is not removed before connection to the battery, a spark may result.

Note: Refer to Figure 6 for details of the bypass harness.

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Illustration 6	g01942543
Schematic of the bypass harness connector

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Illustration 7	g01980938
Typical view of the pin locations on connector P1 for the diagnostic and data link connectors (8) Data link + (9) Data link - (34) J1939 (CAN) - (48) Battery + (50) J1939 (CAN) + (52) Battery + (53) Battery + (55) Battery + (57) Battery + (61) Battery ground (GND) (63) Battery ground (GND) (65) Battery ground (GND) (67) Battery ground (GND) (69) Battery ground (GND) (70) Keyswitch

1. Connect the battery wires from the bypass harness of the electronic service tool to a different battery that is not on the engine.

Results:

• The electronic service tool is operating correctly. -

  Repair: Refer to Troubleshooting, "Ignition Keyswitch and Battery Supply Circuit - Test".

  STOP

• The electronic service tool is not operating correctly. -

  Repair: Perform the following repair:

  1. Make sure that the latest flash file for the application is installed in the ECM. Refer to Troubleshooting, "Flash Programming".

  2. Remove all temporary jumpers and reconnect all connectors.

  3. Contact the Technical Communicator at a Caterpillar dealer.

     Note: This consultation can greatly reduce the repair time.

  4. If the Technical Communicator recommends the use of a test ECM, install a test ECM. Refer to Troubleshooting, "Replacing the ECM".

  5. Use the electronic service tool to recheck the system for active diagnostic codes.

  6. If the fault is eliminated with the test ECM, reconnect the suspect ECM.

  7. If the fault returns with the suspect ECM, replace the ECM.

  8. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP