0383840 JOHNSON DIODE AND LEAD ASSEMBLY

Illustration 1 g01671599Test Step 1. INSPECT ELECTRICAL CONNECTORS AND WIRINGNote: Carefully following this procedure is a good way to identify an intermittent problem.
Illustration 2 g01415758
Location of ECM connectors
Perform a visual inspection of the wiring between the P1 connector and the service tool connector. Look for these problems:
Harness damage that is caused by chafing
Harness damage that is caused by excessive heat
Illustration 3 g01672679
Terminal locations at the service tool connector
(A) +Battery
(B) −Battery
(C) CAN shield
(D) Cat Data Link +
(E) Cat Data Link −
(F) CAN data link −
(G) CAN data link +
Inspect the service tool connector:
Look for moisture on the wiring and on the connector.
Pull on the wires that are associated with the data links. This verifies that the wire is properly attached to the terminal and that the terminal is properly inserted into the connector.
Inspect the P1 connector:
Look for moisture on the wiring and on the connector.
Illustration 4 g01672676
Terminal locations at the P1 ECM connector that are for the data link
(P1-8) Cat Data Link +
(P1-9) Cat Data Link −
(P1-34) CAN data link −
(P1-42) CAN shield
(P1-48) +Battery
(P1-50) CAN data link +
(P1-52) +Battery
(P1-53) +Battery
(P1-61) −Battery
(P1-63) −Battery
(P1-65) −Battery
(P1-70) Keyswitch
Pull on the wires that are associated with the data links. This verifies that the wire is properly crimped to the terminal and that the terminal is properly inserted into the connector. Expected Result:All connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion or of pinch points.Results:
OK - The wiring and the connectors appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem with the wiring or with a connector.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled. Verify that the problem is resolved.STOPTest Step 2. BYPASS THE WIRING FOR THE DATA LINK
Connect the 167-9225 Harness (SERVICE TOOL ADAPTER) to the J1 connector, to the 207-6845 Adapter Cable As, and to the vehicle's battery.
Try to establish communication between Cat ET and the ECM. Expected Result:Cat ET and the ECM communicate.Results:
OK - Cat ET and the ECM communicate.Repair: Cat ET and the ECM communicate when the bypass harness is installed. However, communication cannot be established via the machine's wiring. Disconnect the electrical connector from each of the control modules that is on the specific data link one at a time in order to isolate the problem. Try to establish communication between Cat ET and the ECM after disconnecting each module.The problem is in the control module if disconnecting the module allows Cat ET and the ECM to communicate. If a module is suspect, replace the module. Verify that the problem is resolved.The control module is OK if the problem remains and when the module is disconnected.STOP
Not OK - Cat ET and the ECM do not communicate.Repair: Communication between Cat ET and the ECM is not established when the bypass harness is installed. Temporarily connect a test ECM. Refer to Troubleshooting, "Test ECM Mode". Verify that the problem is resolved.Connect the original ECM and verify that the problem returns. Replace the original ECM.STOPTest Step 3. CHECK THE WIRING FOR THE DATA LINKS FOR A SHORT CIRCUIT
Turn the keyswitch OFF.
Disconnect the negative cable from the vehicle's battery.
Disconnect the P1 connector.
Measure the resistance between the following terminals:
P1-8 Cat Data Link + and P1-63 (-Battery)
P1-9 Cat Data Link − and P1-63 (-Battery)
P1-50 CAN data link + and P1-63 (-Battery)
P1-34 CAN data link − and P1-63 (-Battery)
Measure the resistance between the following terminals:
P1-8 Cat Data Link + and P1-63 (-Battery)
P1-9 Cat Data Link − and P1-63 (-Battery)
P1-50 CAN data link + and P1-53 (+Battery)
P1-34 CAN data link − and P1-53 (+Battery)Expected Result:Each measurement indicates an open circuit.Results:
OK - Each measurement indicates an open circuit. The wiring for the data links does not have a short circuit. Proceed to Test Step 4.
Not OK - At least one measurement is less than five Ohms. The wiring for a data link has a short circuit.Repair: Determine the cause of the short circuit. Repair the problem, when possible. Replace parts, if necessary. Verify that the problem is resolved. STOPTest Step 4. CHECK THE WIRING FOR THE DATA LINKS FOR AN OPEN CIRCUIT
Connect a jumper wire between terminals P1-8 and P1-9.
At the service tool connector, measure the resistance between the terminals for the Cat Data Link.
Connect a jumper wire between terminals P1-34 and P1-50.
At the service tool connector, measure the resistance between the terminals for the CAN data link. Expected Result:All of the resistance measurements indicate a short circuit.Results:
OK - All of the resistance measurements indicate a short circuit.Repair: Remove the jumper wire from the P1 connector.Proceed to Test Step 5.
Not OK - One of the resistance measurements is an open circuit.Repair: Remove the jumper wire from the P1 connector. Determine the cause of the open circuit. Repair the problem, when possible. Replace parts, if necessary. Verify that the problem is resolved. STOPTest Step 5. CHECK THE TERMINATION RESISTORS FOR THE CAN DATA LINKNote: Perform this test only if you are troubleshooting a problem with the CAN data link.
At the service tool connector, measure the resistance between the terminals for the CAN data link. Expected Result:The resistance is between 45 Ohms and 75 Ohms.Res