Circuit Description

WARNING: This page is about a different car, the 2003 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. Connecting a scan tool to the DLC allows communication with the modules for diagnostic purposes. Diagnostic trouble codes (DTCs) may be set due to this symptom and during this diagnostic procedure. Complete the diagnostic procedure in order to ensure all the DTCs are diagnosed and cleared from memory.

Diagnostic Aids

An open in the ignition 1 circuit to the PCM or theft deterrent control module will cause the modules to stop communicating without setting communication DTCs.
If a short to B+ was present, a history U1301 or U1305 will set in the modules. Refer to DTC U1300, U1301, OR U1305 .
If a short to ground was present, a history U1300 or U1305 will set in the modules. Refer to DTC U1300, U1301, OR U1305 .
Disconnecting modules and turning the ignition switch to RUN may cause DTCs in these modules. Check for DTCs in each module upon completion of the required repair.