Serial Peripheral Interface

The serial peripheral interface, SPI bus is an exclusive 3 wire data bus between the BCM and the IPC. The BCM and IPC are the only two modules that communicate over the SPI bus. SPI circuit "A" is used to transmit data from the BCM to the IPC, such as gage, speedometer and MIL control. SPI circuit "B" functions as a communication link back to the BCM from the IPC. The IPC sends information over SPI circuit "B" to the BCM relative to tachometer and speedometer active status as well as messages indicating that the BCM has sent corrupt or invalid data over the SPI to the IPC. The third part of the SPI serial data link is the Clock circuit, the SPI serial data clock circuit is generated in the BCM and transmitted to the IPC so that both modules communications processes are synchronized. All DTC's related to the SPI serial data circuit are handled by the BCM and accessed through the Class 2 serial data bus. Refer to DTC U2000 - U2007 in Body Control System for the diagnostic repair procedures for the SPI serial data circuit.