DTC C0040:24 [START STOP UNIT]

id0902p6021200

Description	Brake switch (No.1 signal) circuit malfunction
Detection condition	• The start stop unit detected the following condition 5 times continuously with the ignition switched ON (engine off or on). ? The brake switch (No.1 signal) is ON for a continuous 3 s or more even though the brake switch (No.2 signal) changes.
Fail-safe	• Determined by brake switch (No.2 signal) with the brake pedal depressed.
Possible cause	• Brake switch connector or terminal malfunction • Brake switch (No.1 signal) malfunction • Start stop unit connector or terminal malfunction • Short to power supply in wiring harness between brake switch terminal D and start stop unit terminal 1C • Start stop unit malfunction

Diagnostic Procedure

Step	Inspection		Action
1	INSPECT BRAKE SWITCH CONNECTOR CONDITION • Switch the ignition off. • Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION.) • 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 5.
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 5. (See BRAKE PEDAL REMOVAL/INSTALLATION [L.H.D.].) (See BRAKE PEDAL REMOVAL/INSTALLATION [R.H.D.].)
3	INSPECT START STOP UNIT CONNECTOR CONDITION • Disconnect the start stop unit 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.
3		No	Repair or replace the connector, then go to Step 5.
4	INSPECT BRAKE SWITCH (No.1 SIGNAL) CIRCUIT FOR SHORT TO POWER SUPPLY • Verify that the brake switch and start stop unit connectors are disconnected. • Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION.) • Switch the ignition ON (engine off or on). • Measure the voltages at brake switch terminal D (wiring harness-side). • Is the voltage 0 V?	Yes	Go to the next step.
4		No	Refer to the wiring diagram and verify whether or not there is a common connector between brake switch terminal D and start stop unit terminal 1C. 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 power supply. • Repair or replace the malfunctioning part. If there is no common connector: • Repair or replace the wiring harness which has a short to power supply. Go to the next step.
5	VERIFY THAT REPAIRS HAVE BEEN COMPLETED • Always reconnect all disconnected connectors. • Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION.) • Clear the DTC for the start stop unit using the M-MDS. (See CLEARING DTC [START STOP UNIT].) • Perform the work of depressing the brake pedal for 3 s or more and then releasing it for 5 times or more with the ignition switched ON (engine off or on). • Retrieve the start stop unit DTCs using the M-MDS. (See DTC INSPECTION [START STOP UNIT].) • Is the same DTC displayed?	Yes	Repeat the inspection from Step 1. • If the malfunction recurs, replace the start stop unit. (See START STOP UNIT REMOVAL/INSTALLATION.) Go to the next step.
5		No	Go to the next step.
6	VERIFY IF OTHER DTCs DISPLAYED • Are any other DTCs displayed?	Yes	Repair or replace the malfunctioning part according to the applicable DTC troubleshooting. (See DTC TABLE [START STOP UNIT].)
6		No	DTC troubleshooting completed.