Information Bus: Testing and Inspection

ECM DATA LINE
1. If all components are not accessible with a scan tool, check for an open in CKT 461 between DLC terminal "M" and S237.
2. If a single component is not accessible with a scan tool, check for an open in CKT 461 between S237 and the component. If the wire is OK, refer to Computers and Controls for Engine Control Module diagnosis, Brakes and Traction Control for ABS diagnosis and to Driver Information Center/Electronic Compass diagnosis.

E & C DATA LINE
1. If all components are not accessible with a scan tool, check for an open in CKT 835 between DLC terminal "J" and S225.
2. If a single component is not accessible with a scan tool, check for an open in CKT 835 between S225 and the component.

CIRCUIT OPERATION
There are two data lines that can be accessed with a scan tool. The 461 circuit data line is the ECM Data Line. It allows the Engine Control Module, Heater and A/C Control Assembly (C 68) and Electronic Brake Control Module (EBCM) (if equipped) to communicate by transmitting data through CKT 461. The 835 circuit data line is the Entertainment and Comfort (E & C Bus) Data Line. It allows the Radio, Heater and A/C Control Assembly (C68) and Heater and A/C Control Interface Module to communicate via CKT 835.

A scan tool can be connected to the DLC; this allows the scan tool to communicate with both the ECM Data Line and E & C Data Lines. System operations can then be monitored for diagnostic purposes.