Procedures For Determining The Location Of A Malfunction: Pcm

WARNING: This page is about a different car, the 2005 Mazda RX-8. However, it is still accessible from the selected car via links, so may be relevant.

Check the display of DTC U0121 and/or U0155, using the SST (WDS or equivalent). (See DTC TABLE [MULTIPLEX COMMUNICATION SYSTEM] .)

Referring to the following table, determine the malfunctioning part of the CAN system.

PCM COMMUNICATION STATUS AND MALFUNCTION LOCATION

Module	Communication status				Malfunction location
Module	ABS HU/CM DSC HU/CM	TCM	Keyless control module	Instrument cluster	Malfunction location
PCM	Error	Error	Error	Error	Wiring harness 1 Wiring harness 3 PCM
	Error	OK	OK	OK	Wiring harness 5 ABS HU/CM DSC HU/CM
	OK	Error	OK	OK	Wiring harness 4 TCM
	OK	OK	Error	OK	Wiring harness 7 Keyless control module
	OK	OK	OK	Error	Wiring harness 8 Wiring harness 10 Wiring harness 12 Instrument cluster