Multiplex Communication System [Multiplex Communication System]: Flowchart

WARNING: This page is about a different car, the 2008 Mazda 5. However, it is still accessible from the selected car via links, so may be relevant.

Use the following flowchart to verify the cause of the trouble.

FLOWCHART

STEP	INSPECTION		ACTION
1	INSPECT COMMUNICATION CONDITION Is there a response from the following modules? PCM TCM EHPAS control module ABS HU/CM Instrument cluster Climate control unit Information display Audio unit (base unit) Car-navigation unit HF/TEL unit BCM	Yes	Go to the next step.
1		No	Go to Step 6.
2	INSPECT DTC INDICATION Using the M-MDS, inspect if DTCs are displayed for the following module: PCM TCM EHPAS control module ABS HU/CM Instrument cluster Climate control unit Information display Audio unit (base unit) Car-navigation unit HF/TEL unit BCM Are any DTCs displayed?	Yes	Go to the next step.
2		No	Go to "SYMPTOM TROUBLESHOOTING".
3	INSPECT CAN SYSTEM-RELATED DTC Are any DTCs other than the CAN related displayed? (See DTC TABLE [MULTIPLEX COMMUNICATION SYSTEM] .)	Yes	Repair the malfunctioning part by following the related DTC inspection. Go to the next step.
3		No	Go to the next step.
4	INSPECT CAN SYSTEM-RELATED DTC Are any of the CAN related DTCs displayed? (See DTC TABLE [MULTIPLEX COMMUNICATION SYSTEM] .)	Yes	Repair the malfunctioning part by following the DTC inspection. Go to the next step.
4		No	Troubleshooting completed.
5	VERIFY TROUBLESHOOTING COMPLETED Clear the DTC from the CAN system-related modules using the M-MDS. Start the engine. Are any of the CAN related DTCs displayed?	Yes	Go back to Step 3.
5		No	Troubleshooting completed.
6	INSPECT MODULES THAT DO NOT RESPOND Inspect the power supply and the ground circuit for any units that do not respond. Are they normal?	Yes	Go to the next step.
6		No	Repair the malfunctioning part, then go back to Step 1.
7	INSPECT CONNECTOR AND WIRING HARNESS BETWEEN MODULES THAT DO NOT RESPOND AND DLC-2 Turn the ignition switch to the LOCK position. Inspect the wiring harness and connector between any module that does not respond and the DLC-2. PCM-DLC-2 1AM-F 1AI-E TCM-DLC-2 B-F E-E EHPAS control module-DLC-2 2D-F 2B-E ABS HU/CM-DLC-2 H-F L-E Instrument cluster-DLC-2 11-F 1K-E 1M-L 1O-K Climate control unit-DLC-2 1X-L 1W-K Information display-DLC-2 J-L L-K Audio unit-DLC-2 1O-L 1Q-K Car-navigation unit-DLC-2 1O-L 1Q-K HF/TEL unit-DLC-2 Q-L R-K BCM-DLC-2 3D-L 3G-K Is there any malfunction?	Yes	Repair the malfunctioning part, then go back to Step 1.
7		No	Go to the next step.
8	INSPECT WIRING HARNESS Turn the ignition switch to the ON position Engine off). Measure the voltage between the following terminals. DLC-2 terminals F-ground DLC-2 terminals E-ground DLC-2 terminals L-ground DLC-2 terminals K-ground Is the voltage 2.0-3.0 V?	Yes	Go to the next step.
8		No	Go to Step 13.
9	INSPECT WIRING HARNESS Turn the ignition switch to the LOCK position. Measure the resistance between the following terminals. DLC-2 terminals F and E DLC-2 terminals L and K Is the resistance 59-65 ohms?	Yes	Replace the modules that do not respond, then go back to Step 1.
9		No	Go to the next step.
10	INSPECT PCM Disconnect the PCM connector. Measure the resistance between following terminals. PCM terminals 1AM and 1AI (part-side) Is the resistance 118-130 ohms?	Yes	Go to the next step.
10		No	Replace the PCM, then go to the next step.
11	INSPECT INSTRUMENT CLUSTER Disconnect the instrument cluster connector. Measure the resistance between the following terminals. Instrument cluster terminals 11 and 1K (part-side) Instrument cluster terminals 1M and 10 (part-side) Is the resistance 118-130 ohms ?	Yes	Go to next step.
11		No	Replace the instrument cluster, then go to the next step.
12	INSPECT BCM Disconnect the BCM connector. Measure the resistance between the following terminals. BCM terminal 3D and 3G (part-side) Is the resistance 118-130 ohms ?	Yes	Go to next step.
12		No	Replace the BCM, then go to the next step.
13	CLASSIFY WIRING HARNESS MALFUNCTION OR MODULE MALFUNCTION Turn the ignition switch to the LOCK position. Disconnect the connector of any unit that does not respond. (If there are two or more units that do not respond, disconnect only one of the units.) Turn the ignition switch to the ON position. Measure the voltage between the following terminals. DLC-2 terminals F-ground DLC-2 terminals E-ground DLC-2 terminals L-ground DLC-2 terminals K-ground Is voltage 2.0-3.0 V?	Yes	Go to the next step.
13		No	Retry this step with other module connector disconnected. If all units that do not respond are disconnected, go to Step 15.
14	INSPECT WIRING HARNESS OF ANY UNIT THAT DOES NOT RESPOND Turn the ignition switch to the LOCK position. Inspect for continuity between the following connector terminals of any disconnected unit. PCM 1AM-other terminals 1Al-other terminals TCM B-other terminals E-other terminals EHPAS control module 2D-other terminals 2B-other terminals ABS HU/CM H-other terminals L-other terminals Instrument cluster 11-other terminals 1K-other terminals 1M-other terminals 10-other terminals Climate control unit 1X-other terminals 1W-other terminals Information display J-other terminals L-other terminals Audio unit 1Q-other terminals 1Q-other terminals Car-navigation unit 1Q-other terminals 1Q-other terminals HF/TEL unit Q-other terminals R-other terminals BCM 3D-other terminals 3G-other terminals Is there continuity?	Yes	Repair or replace the wiring harness, then go back to Step 1.
14		No	Replace the disconnected unit, then go back to Step 1.
15	INSPECT CAN RELATED WIRING HARNESS Inspect the related wiring harnesses (CAN_L and/or CAN_H) for the short circuit (to power supply or ground). Is the wiring harness normal?	Yes	Repair or replace the wiring harness, then go back to Step 1.
15		No	Go back to Step 1.