3512B Generator Set Engine Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the Cat Data Link or if the diagnostic code in Table 1 is active or easily repeated.

The Cat Data Link is used for communication between electronic modules. The Cat Data Link is used to communicate information from the engine's Electronic Control Module (ECM) to other electronic systems. The Cat Data Link is used for programming and for troubleshooting the ECM.

The engine's ECM communicates with Caterpillar Electronic Technician (ET) in order to share information on engine status and on engine diagnostics. Cat ET can also be used to configure the engine's parameters. This information will not be available if communication fails between the engine's ECM and Cat ET.

Illustration 1	g01624718
Typical example

Illustration 2	g01156133
P1 ECM connector (P1-8) Cat Data Link + (P1-9) Cat Data Link −

Illustration 3	g01161996
C-C18/(TB-C1 customer or L-C1/L-C2 EMCP 3) connectors (Terminal g) Cat Data Link + (Terminal h) Cat Data Link −

Illustration 4	g01161999
Service tool connector (Terminal D) Cat Data Link + (Terminal E) Cat Data Link −

Illustration 5	g01622856
Connector locations (1) A-C1/E-C2/E-C1 Right hand cross over harness (2) A-C2/J-C2/J-C1 Right hand cross over harness (3) A-C90/P-C1 Connectors for the power distribution panel (4) A-C91/P-C2 Connectors for the power distribution panel (5) A-C60 Connector for the prelube motor (6) A-C92/F-C1/F-C2/G-C6 Connectors for a RH Control panel (7) C-C22 Primary ECM connector P2 (8) C-C15 Primary ECM connector P1 (9) C-C28 Secondary ECM connector P2 (10) C-C29 Secondary ECM connector P1 (11) C-C47 Connector for the power relay panel (12) C-C17/F-C1/F-C2/G-C6 Connectors for a LH Control panel (13) C-C18/(TB-C1 customer or L-C1/L-C2 EMCP 3) connectors (14) C-C2/J-C1/J-C2 Left hand cross over harness (15) C-C1/E-C1/E-C2 Left hand cross over harness

Test Step 1. Inspect Electrical Connectors and Wiring

1. Remove power from the ECM.

2. Thoroughly inspect the J1/P1 ECM connector and the J2/P2 ECM connector. Inspect all of the connectors that are associated with the circuit.

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

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

4. Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.

5. Check the harness and wiring for abrasion and for pinch points.

Expected Result:

All connectors, pins, and sockets are completely inserted and coupled. The harness and wiring are free of corrosion, of abrasion, and of pinch points.

Results:

• OK - The harness and the connectors appear to be OK. Proceed to Test Step 2.

• Not OK - The connectors and/or the wiring are not OK.

  Repair: Repair the connectors and/or the wiring. Replace parts, if necessary. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled. Verify that the original problem is resolved.

  STOP

Test Step 2. Check for a Short Circuit

1. Disconnect the P1 ECM connector.

2. Disconnect Cat ET from the service tool connector.

3. Disconnect any other control modules from the Cat Data Link. Refer to the electrical schematic in order to identify other control modules on the Cat Data Link.

4. Measure the resistance between the points that are listed in Table 2. Be sure to wiggle the wires in the harnesses as you make each resistance measurement.
   Show/hide table

   Table 2

   Resistance Measurements for the Cat Data Link
   Connector and Terminal	Terminal
   P1-8 (Cat Data Link +)	All of the other terminals on the P1 connector
   	Ground stud
   P1-9 (Cat Data Link -)	All of the other terminals on the P1 connector
   	Ground stud

Expected Result:

Each check of the resistance indicates an open circuit.

Results:

• OK - Each check of the resistance indicates an open circuit. Proceed to Test Step 3.

• Not OK - At least one check of the resistance does not indicate an open circuit. There is a short circuit in the harness or in a connector.

  Repair: Repair the connectors and/or the wiring. Replace parts, if necessary. Verify that the original problem is resolved.

  STOP

Test Step 3. Check for an Open Circuit

1. Fabricate a jumper wire. Use the jumper wire in order to create a short circuit between terminals D (Cat Data Link +) and terminal E (Cat Data Link −) on the service tool connector.

2. Measure the resistance between P1-8 (Cat Data Link +) and P1-9 (Cat Data Link −).

3. Measure the resistance between the terminals at the connector for each control module that was connected to the Cat Data Link. Refer to Illustration 1.

4. Remove the jumper wire from the service tool connector.

Expected Result:

Each check of the resistance indicates a short circuit.

Results:

• OK - Each check of the resistance indicates a short circuit.

  Repair: Perform the following procedure:

  1. Connect the J1/P1 connectors. Connect Cat ET to the service tool connector.

  2. Check the Cat Data Link for proper operation. If the Data Link does not operate correctly, there may be a problem with the ECM.

     Temporarily install a new ECM. Check the Cat Data Link again. If the new ECM solves the problem, install the original ECM and verify that the original problem returns. If the new ECM operates correctly and the original ECM does not operate correctly, replace the original ECM. Refer to Troubleshooting, "ECM - Replace".

  STOP

• Not OK - At least one check of the resistance does not indicate a short circuit. There is an open circuit or excessive resistance in the harness. There may be a problem with a connector.

  Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. Verify that the original problem is resolved.

  STOP