U1128, Loss Of Serial Communications - IRC: Notes
NOTE:
To identify wire colors and components on Class 2 serial data line, see appropriate wiring diagram in DATA LINK CONNECTORS article in WIRING DIAGRAMS.
Every 2 seconds while ignition switch is in RUN position, control modules that communicate on class 2 data bus transmit a performance condition signal to indicate system is operating properly. Signal is then transmitted to BCM. DTC U1128 will set when BCM does not receive signal from IRC after 3 consecutive monitoring cycles. DTC U1128 will clear when IRC transmits signal to BCM or when scan tool is used.