0388868 JOHNSON CABLE ASSY., Instrument

Illustration 1 g01072392
Typical configurationTransmission ControlThe following characteristics are determined by a vehicle speed sensor in the transmission:
Transmission shift points
Engine rpm
LoadThe sensors for power train control provide signals to the vehicle control module of the "Powertrain Data Link". The vehicle control module of the "Powertrain Data Link" then communicates with the ECM. The ECM receives a request from the "Powertrain Data Link". The ECM responds by momentarily limiting the following characteristics:
Engine rpm
Torque
Both engine rpm and torqueThe presence of an active J1922 data link circuit can be determined by observing the "Powertrain Status" screen on the Caterpillar Electronic Technician (ET). The status screen will display "Installed" if the proper software is installed in the ECM, and there is no action that is being requested at that time by any of the control modules on the data link.If an action is being requested by one of the vehicle control modules, the display will indicate the control that is making the request (traction control or transmission control) or a combination of the two. Power train control is also displayed in the upper right hand corner of the display status screen. This space is replaced by the low oil pressure indicator, when a condition of low oil pressure exists.J1922 Data LinkSAE J1922 is standard with all software.Note: The circuit for the J1922 data link must be twisted pair wiring. Twisted pair wiring is used to reduce electromagnetic interference. If a section of wiring must be replaced, the new wires must also be a twisted pair. Use care to maintain the polarity of the original wiring when the pins and the sockets are being installed into the connectors.J1939 Data LinkSAE J1939 is standard with all software.Note: The wiring for the J1939 data link is a shielded twisted pair cable and the wiring is not serviceable. The wiring for the entire circuit must be replaced when the wiring is damaged.
Illustration 2 g01072393
Schematic for power train data link
Illustration 3 g01072394
Terminal locations at the ECMTest Step 1. Inspect the Electrical Connectors and the Wiring
Thoroughly inspect the J1/P1 ECM connector, the firewall bulkhead connector, the connectors for the power train control module, and the connector terminals for the SAE J1922 data link or the connector terminals for the J1939 data link. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the SAE J1922 data link or the J1939 data link.Refer to Illustration 3.
Check the allen head screws for each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque value.
Check the harness and wiring for abrasion and for pinch points from the data link connectors back to the ECM.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 - Proceed to Test Step 2.
Not OK - Repair: Perform the following 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 repair eliminates the problem.STOPTest Step 2. Check for Active Diagnostic Codes
Connect Cat ET to the data link connector.
Turn the keyswitch to the ON position.
Monitor the active diagnostic code screen on Cat ET. Check and record active diagnostic codes.Expected Result:There is an active diagnostic code for the SAE J1922 data link or for the SAE J1939 data link.Note: The "Powertrain Data Link" parameter is a customer parameter that must not be programmed to J1939, or J1922 and J1939, unless the J1939 data link is being used.Results:
J1939 - Proceed to Test Step 3.
J1922 - Proceed to Test Step 5.
Not OK - Proceed to Test Step 4.Test Step 3. Check the Devices on the J1939 Data Link.
Connect Cat ET to the data link connector.
Access the special test "J1939 Receive Communication Status". The special tests are located under the "Diagnostic menu".
Cat ET will display the J1939 sources that have transmitted at least one good message that has been successfully received by the ECM. If the ECM has not received any messages from a source, that source will not be displayed. Examples of devices that can use the J1939 data link include the following switches:
Switches that are programmed to "Instrument Cluster"
Switches that are programmed to "Body Controller"
Switches that are programmed to "Cab Controller"
Cat ET will display the J1939 source in the "Description" column. The "Status" column displays the status of the device.
If an expected message is not received from a device, Cat ET will display "Not Receiving".
The status screen on Cat ET can be set to display the status of a device that is not working. The status screen will display "No Comm" if a message is not received from the device.Expected Result:Cat ET displays the devices that are used on the vehicle and the ECM is receiving messages from the devices.Results:
OK - The ECM is receiving messages from the devices that are installed on the vehicle.STOP
Not OK - The ECM is not receiving messages from the devices that are installed on the vehicle.Repair: The devices that can be programmed to use the J1939 data link can be circuits with two wires or circuits with three wires. Loose connections are the most frequent problem. Repair the suspect component or replace the suspect component. This may include the connectors, the wiring, and/or the device. Ensure that the connectors are free of corrosion.STOPTest Step 4. Check the Power Train Status Screen
Table 1
Status Group for the Power Train &