Scan Tool Does Not Communicate With Keyword 82 Data Line (& Keyword 2000)

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

CIRCUIT OPERATION
Modules connected to the Keyword serial data circuit utilize a request and response type arrangement. Similar to the UART system. Operating information and commands are not exchanged among the modules. Connecting a scan tool to the DLC allows communication with the modules for diagnostic purposes only.

The exception, however, are the Engine Control Module (ECM), Transmission Control Module (TCM), and EBTCM. These modules, in addition to the Keyword serial data circuits, exchange information via the Controlled Area Network (CAN) data circuits. Diagnostic trouble codes (DTCs) are set by these modules when a condition exists with the CAN circuits or an important message is not received. Refer to the individual DTC tables to diagnose CAN malfunctions.

DIAGNOSTIC AIDS
^ Use a J35616-A when probing or checking electrical connector terminals. The J35616-A prevents terminal damage, plus checks for proper terminal contact tension.
^ If the malfunction is intermittent refer to Inducing Intermittent Fault Conditions in Diagrams, Diagnostic Aids, Troubleshooting Tools.

TEST DESCRIPTION
4. The data link connector terminal specific to the module that is not communicating and terminals 4 and 5, provide the connection to the Keyword serial data circuit and the signal ground circuit respectively.
5. Proper power and ground to the module, that is not communicating, is essential.
8. The Keyword serial data circuit is shorted to voltage or ground. The condition may be due to the wiring or due to a malfunction in one of the modules. When testing the wiring for a short, make sure there is not a module connected to the wire being tested.
8. Since the short is not in the wiring harness the malfunction is due to one of the modules.