Diagnostic Procedure

WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

DTC P0685:00 PCM (SKYACTIV-G 2.0, SKYACTIV-G 2.5) - DIAGNOSTIC POROCEDURE

STEP	INSPECTION		ACTION
1	VERIFY FREEZE FRAME DATA (MODE 2)/SNAPSHOT DATA HAS BEEN RECORDED Has the FREEZE FRAME DATA (Mode 2)/snapshot data been recorded?	Yes	Go to the next step.
1		No	Record the FREEZE FRAME DATA (Mode 2)/snapshot data on the repair order, then go to the next step.
2	VERIFY RELATED REPAIR INFORMATION AVAILABILITY Verify related Service Bulletins and/or on-line repair information availability. Is any related repair information available?	Yes	Perform repair or diagnosis according to the available repair information. If the vehicle is not repaired, go to the next step.
2		No	Go to the next step.
3	INSPECT MAIN RELAY Switch the ignition off. Remove the main relay. Inspect the main relay. (See RELAY INSPECTION .) Is there any malfunction?	Yes	Replace the main relay, then go to Step 10.
3		No	Go to the next step.
4	INSPECT MAIN RELAY POWER SUPPLY CIRCUIT FOR SHORT TO GROUND OR OPEN CIRCUIT Main relay is removed. Measure the voltage at the main relay terminal C (wiring harness-side). Is the voltage B+?	Yes	Go to the next step.
4		No	Inspect the MAIN 200 A fuse and ENG.MAIN 40 A fuse. If the fuse is blown: Refer to the wiring diagram and verify whether or not there is a common connector between MAIN 200 A fuse and main relay terminal C. If there is a common connector: Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground. Repair or replace the malfunctioning part. If there is no common connector: Repair or replace the wiring harness which has a short to ground. Replace the fuse. If the fuse is damaged: Replace the fuse. If all fuses are normal: Refer to the wiring diagram and verify whether or not there is a common connector between battery positive terminal and main relay terminal C. If there is a common connector: Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for an open circuit. Repair or replace the malfunctioning part. If there is no common connector: Repair or replace the wiring harness which has an open circuit. Go to Step 10.
5	INSPECT ENGINE2 15 A FUSE Remove the ENGINE2 15 A fuse. Inspect the ENGINE2 15 A fuse. Is there any malfunction?	Yes	If the fuse is blown: Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals: Main relay terminal D-PCM terminal 2S Main relay terminal D-PCM terminal 2T If there is a common connector: Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground. Repair or replace the malfunctioning part. If there is no common connector: Repair or replace the wiring harness which has a short to ground. Replace the fuse. If the fuse is damaged: Replace the fuse. Go to Step 10.
5		No	Reinstall the ENGINE2 15 A fuse, then go to the next step.
6	INSPECT PCM POWER SUPPLY CIRCUIT FOR SHORT TO GROUND Main relay is removed. Inspect for continuity between main relay terminal D (wiring harness-side) and body ground. Is there continuity?	Yes	If the short to ground circuit could be detected in the wiring harness: Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals: Main relay terminal D-PCM terminal 2S Main relay terminal D-PCM terminal 2T If there is a common connector: Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground. Repair or replace the malfunctioning part. If there is no common connector: Repair or replace the wiring harness which has a short to ground. If the short to ground circuit could not be detected in the wiring harness: Replace the PCM (short to ground in the PCM internal circuit). (See PCM REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Go to Step 10.
6		No	Go to the next step.
7	INSPECT PCM CONNECTOR CONDITION Disconnect the PCM connector. Inspect for poor connection (such as damaged/pulled-out pins, corrosion). Is there any malfunction?	Yes	Repair or replace the connector and/or terminals, then go to Step 10.
7		No	Go to the next step.
8	INSPECT PCM GROUND CIRCUIT FOR OPEN CIRCUIT Main relay is removed. Verify that the PCM connector is disconnected. Inspect for continuity between the following harnesses: PCM terminal 1BZ (wiring harness-side)-Body ground PCM terminal 2AA (wiring harness-side)-Body ground Is there continuity?	Yes	Go to the next step.
8		No	Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals: PCM terminal 1BZ (wiring harness-side)-Body ground PCM terminal 2AA (wiring harness-side)-Body ground If there is a common connector: Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for an open circuit. Repair or replace the malfunctioning part. If there is no common connector: Inspect for the following: Open circuit between PCM and body ground Loose or lifting ground point Repair or replace the malfunctioning part. Go to Step 10.
9	INSPECT PCM POWER SUPPLY CIRCUIT FOR OPEN CIRCUIT Main relay is removed. Verify that the PCM connector is disconnected. Inspect for continuity between the following terminals (wiring harness-side): Main relay terminal D-PCM terminal 2S Main relay terminal D-PCM terminal 2T Is there continuity?	Yes	Go to the next step.
9		No	Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals: Main relay terminal D-PCM terminal 2S Main relay terminal D-PCM terminal 2T If there is a common connector: Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for an open circuit. Repair or replace the malfunctioning part. If there is no common connector: Repair or replace the wiring harness which has an open circuit. Go to the next step.
10	VERIFY DTC TROUBLESHOOTING COMPLETED Always reconnect all disconnected connectors. Clear the DTC from the PCM memory using the M-MDS. (See AFTER REPAIR PROCEDURE [PCM (SKYACTIV-G 2.0, SKYACTIV-G 2.5)] .) Start the engine and warm it up completely. Perform the Pending Trouble Code Access Procedure. (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.0, SKYACTIV-G 2.5)] .) Is the PENDING CODE for this DTC present?	Yes	Repeat the inspection from Step 1. If the malfunction recurs, replace the PCM. (See PCM REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Go to the next step.
10		No	Go to the next step.
11	VERIFY AFTER REPAIR PROCEDURE Perform the "AFTER REPAIR PROCEDURE". (See AFTER REPAIR PROCEDURE [PCM (SKYACTIV-G 2.0, SKYACTIV-G 2.5)] .) Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [PCM (SKYACTIV-G 2.0, SKYACTIV-G 2.5)] .)
11		No	DTC troubleshooting completed.