Scan Tool Does Not Communicate With Class 2 Device: Description

Modules connected to class 2 serial data circuit are monitored for communication during normal vehicle operation. Operating information and commands are exchanged between modules. Connecting scan tool to DLC allows communication with control modules for data messages, diagnostics and other information communications. DTCs may set due to symptom and during diagnostic procedures. Complete diagnostic procedure to ensure all DTCs are diagnosed and cleared from memory.

BCM detects that ignition is ON and sends appropriate power mode message to other modules. BCM must be connected to DLC for any other modules to communicate with scan tool. When class 2 serial data circuit is shorted to ground, DTC U1300 or U1305 will be set. When class 2 serial data circuit is shorted to power, DTC U1301 or U1305 will be set.