Circuit Description

Simple Bus Interface (SBI) provides communications path between all door modules. Left Front Door Module (LFDM) contains both class 2 serial data line and SBI circuits allowing it to relay messages between class 2 serial data line and SBI. Each module connected to SBI is assigned its own recognition code. This code is used to identify which modules are communicating by periodically sending State Of Health (SOH) messages. When ignition switch is in RUN position, each module communicating on SBI sends SOH message every 2 seconds to ensure proper system operation.

DTC U1170 is set when any SBI communications problem between LFDM and Left Front Power Window Switch (LFPWS) occurs. DTCs U1300 (class 2 serial data line shorted to ground) or U1301 (class 2 serial data line shorted to voltage) must not be current or diagnostic will not run. DTC U1170 is stored in LFDM memory. No driver warning message will be displayed for this DTC. Loss of SBI will cause LFDM to use default values for initialization data.

Under all fault conditions, DTC U1170 will clear automatically when SBI becomes operational again or with each ignition cycle. History DTC will clear after 50 consecutive ignition cycles if condition for malfunction is no longer present. Current and history DTCs can also be cleared using scan tool or on-board diagnostic system.