Diagnostic Procedure

WARNING: This page is about a different car, the 2016 Mazda CX-5. However, it is still accessible from the selected car via links, so may be relevant.

Step	Inspection		Action
1	INSPECT BRAKE SWITCH CONNECTOR CONDITION Switch the ignition to off. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Disconnect the brake switch connector. Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection. Is the connector normal?	Yes	Go to the next step.
1		No	Repair or replace the connector, then go to Step 7.
2	INSPECT BRAKE SWITCH (NO. 1 SIGNAL) Inspect the brake switch (No. 1 signal). (See BRAKE SWITCH INSPECTION .) Is the brake switch (No. 1 signal) normal?	Yes	Go to the next step.
2		No	Replace the brake switch, then go to Step 7. (See BRAKE PEDAL REMOVAL/INSTALLATION .)
3	INSPECT BRAKE SWITCH (NO. 1 SIGNAL) POWER SUPPLY CIRCUIT FOR OPEN CIRCUIT OR SHORT TO GROUND Verify that the brake switch connector is disconnected. Connect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Switch the ignition ON (engine off or on). Measure the voltage at brake switch terminal A (vehicle wiring harness side). Is the voltage B+?	Yes	Go to the next step.
3		No	Inspect the STOP 10 A fuse. If a fuse is burnt out: Repair or replace the wiring harness which is shorted to ground. Replace the burnt out fuse. If a fuse is damaged: Replace the damaged fuse. If the fuse is normal: Repair or replace the wiring harness which has an open circuit. Go to Step 7.
4	INSPECT START STOP UNIT CONNECTOR CONDITION Disconnect the start stop unit connector. Switch the ignition to off. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection. Is the connector normal?	Yes	Go to the next step.
4		No	Repair or replace the connector, then go to Step 7.
5	INSPECT BRAKE SWITCH (NO. 1 SIGNAL) CIRCUIT FOR SHORT TO GROUND Verify that the brake switch and start stop unit connectors are disconnected. Inspect for continuity between brake switch terminal D (vehicle wiring harness side) and body ground. Is there continuity?	Yes	Repair or replace the wiring harness which is shorted to ground, then go to Step 7.
5		No	Go to the next step.
6	INSPECT BRAKE SWITCH (NO. 1 SIGNAL) CIRCUIT FOR OPEN CIRCUIT Verify that the brake switch and start stop unit connectors are disconnected. Inspect the wiring harness for an open circuit between brake switch terminal D (vehicle wiring harness side) and start stop unit terminal 1C (vehicle wiring harness side). Is there continuity?	Yes	Go to the next step.
6		No	Repair or replace the wiring harness which has an open circuit, then go to the next step.
7	VERIFY THAT REPAIRS HAVE BEEN COMPLETED Reconnect all the disconnected connectors. Reconnect the disconnected negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Clear DTC for the start stop unit using the M-MDS. (See CLEARING DTC [START STOP UNIT] .) With the ignition switched ON (engine off or on), perform the work of depressing the brake pedal for 3 s or more and then releasing it for 5 or more times. Perform the DTC inspection for the start stop unit using the M-MDS. (See DTC INSPECTION [START STOP UNIT] .) Is DTC C0040:23 displayed?	Yes	Repeat the inspection from Step 1. If the malfunction recurs, replace the start stop unit, then go to the next step. (See START STOP UNIT REMOVAL/INSTALLATION .)
7		No	Go to the next step.
8	VERIFY IF OTHER DTCs DISPLAYED Are any other DTCs displayed?	Yes	Repair the malfunctioning part according to the applicable DTC troubleshooting. (See DTC TABLE [START STOP UNIT] .)
8		No	DTC troubleshooting completed.