ADAPTER-MUFFLER 7B7937 - Caterpillar

Illustration 5 g03705906
Typical view of the diagnostic connector from the wire side
(A) Switched battery +
(B) Battery ground (GND)
(D) Data link +
(E) Data link -
Table 3
Troubleshooting Test Steps Values Results
4. Bypass the Wiring for the Diagnostic Connector
A. Disconnect the wires from pin A and pin B of the diagnostic connector.
Note: If the diagnostic connector is mounted on the engine, perform Steps B to D. If the diagnostic connector is mounted off the engine, perform Step E.
B. Disconnect the wires from P2:56 and P2:64.
C. Fabricate a jumper wire in order to connect pin A of the diagnostic connector to P2:56.
D. Fabricate a jumper wire in order to connect pin B of the diagnostic connector to P2:64.
E. Fabricate a jumper wire in order to connect pin "A" of the diagnostic connector to battery+ and pin "B" to the battery-.
F. Connect the electronic service tool to the diagnostic connector that is on the engine harness or on the application.
G. Turn the keyswitch to the ON position. The power lamp should illuminate on the communications adapter.
Other devices are OK
Result: 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.
Result: The power lamp is not illuminated.
Proceed to Test Step 6.
5. Check the Data Link Connections
A. Turn the keyswitch to the OFF position.
B. Disconnect the communications adapter from the diagnostic connector.
C. If the diagnostic connector is installed on the application, disconnect connector P1 from the ECM. Check the resistance between P1:20 and pin "D" on the diagnostic connector. Check the resistance between P1:28 and pin "E" on the diagnostic connector.
D. If the diagnostic connector is installed on the engine, disconnect P2 from the ECM. Check the resistance between P2:47 and pin "D" on the diagnostic connector. Check the resistance between P2:55 and pin "E" on the diagnostic connector.
Less than ten Ohms
Result: The resistances are less than ten Ohms.
Proceed to Test Step 6.
Use the electronic service tool to clear all logged diagnostic codes. Verify that the repair eliminates the fault.
Result: At least one of the resistances is greater than ten Ohms.
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.
6. Change the Electronic Service Tool Components
A. If another electronic engine is available, connect the electronic service tool to the other engine. Ensure that the same cables are used.
B. Turn the keyswitch to the ON position. Determine if the electronic service tool operates correctly on the other engine.
C. If another engine is not available, obtain a replacement communications adapter and a replacement set of cables. Ensure that the cables for the electronic service tool are a complete set.
D. Install the replacement communications adapter and