Supplemental Restraint System (Diagnostics - Introduction): Other Toyota 4Runner V

PRECAUTION

Note. Malfunction symptoms of SRS parts are difficult to confirm. DTCs are the most important source of information when troubleshooting. During troubleshooting, always confirm DTCs before disconnecting the cable from the negative (-) battery terminal. For minor collisions where SRS parts do not deploy, always inspect the SRS parts. Before performing repairs, remove the airbag sensors if any kind of impact is likely to occur to an airbag sensor during repairs. Never use SRS parts from another vehicle. When replacing SRS parts, replace them with new ones. Never disassemble or attempt to repair SRS parts. If an SRS part has been dropped, or if there are any cracks, dents or other defects in the case, bracket or connector, replace the SRS part with a new one. Use an ohmmeter/voltmeter with high impedance (10 kohms/V minimum) for troubleshooting the electrical circuits. Information labels are attached to the periphery of SRS parts. Follow the cautions and instructions on the labels. After work on the SRS is completed, perform the SRS warning light check. Refer to DIAGNOSIS SYSTEM . When the cable is disconnected from the negative (-) battery terminal, the memory settings of each system are cleared. Because of this, be sure to write down the settings of each system before starting work. When work is finished, reset the settings of each system as before. Never use a backup power supply from outside the vehicle to avoid clearing the memory in a system. If the vehicle is equipped with a mobile communication system, refer to the Precaution in the Introduction information.

HINT

In the airbag system, the center airbag sensor, front airbag sensor LH and RH, side airbag sensor LH and RH, rear airbag sensor LH and RH, and rear floor side airbag sensor are collectively referred to as the airbag sensors.

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1. HANDLING PRECAUTIONS FOR AIRBAG SENSORS Before starting the following operations, wait for at least 90 seconds after disconnecting the cable from the negative (-) battery terminal: Replacement of the airbag sensors. Adjustment of the front/rear doors of the vehicle equipped with side airbags and curtain shield airbags (fitting adjustment). When connecting or disconnecting the airbag sensor connectors, make sure that each sensor is installed in the vehicle. Do not use airbag sensors which have been dropped during operation or transportation. Do not disassemble the airbag sensors.
2. INSPECTION PROCEDURE FOR VEHICLE INVOLVED IN ACCIDENT When the airbag has not deployed, confirm the DTCs by checking the SRS warning light. If there is any malfunction in the SRS airbag system, perform troubleshooting. When any of the airbags have deployed, replace the airbag sensors and check the installation condition.
3. SRS CONNECTORS SRS connectors are located as shown in the following illustration. Item Application Terminal Twin-lock Mechanism Connectors 8, 11, 12, 13, 14, 23, 24, 35, 36 Activation Prevention Mechanism Connectors 2, 4, 7, 13, 19, 21 Half Connection Prevention Mechanism Connectors 8, 12, 13, 19, 21, 23, 36 Connector Position Assurance Mechanism Connectors 10, 16, 18, 38 Connector Lock Mechanism (1) Connectors 6 Connector Lock Mechanism (2) Connectors 2, 4 Improper Connection Prevention Lock Mechanism Connectors 1, 3 All connectors in the SRS, except the seat position sensor connector, are colored yellow to distinguish them from other connectors. These connectors have special functions and are specially designed for the SRS. All SRS connectors use durable gold-plated terminals which are placed in the locations shown below to ensure high reliability. Terminal twin-lock mechanism: All connectors with a terminal twin-lock mechanism have a two-piece component consisting of a housing and spacer. This design enables the terminal to be locked securely by two locking devices (the retainer and the lance) to prevent terminals from coming out. Activation prevention mechanism: All connectors with an activation prevention mechanism contain a short spring plate. When these connectors are disconnected, the short spring plate creates a short circuit by automatically connecting the positive (+) and negative (-) terminals of the squib. Half connection prevention mechanism: If the connector is not completely connected, the connector is disconnected by the force of the spring so that no continuity exists. Connector position assurance mechanism: The CPA (yellow part) slides only when the housing lock (white part) is completely engaged, which completes the connector engagement. Connector lock mechanism (1): Locking the connector lock button connects the connector securely. Connector lock mechanism (2): Both the primary lock with holder lances and the secondary lock with retainer prevent the connectors from becoming disconnected. Improper connection prevention lock mechanism: When connecting the holder, the lever is pushed into the lock position by rotating around the A axis to lock the holder securely.

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1. GENERAL In conjunction with the impact absorbing structure for a front collision, the SRS (Supplemental Restraint System) steering pad, instrument panel passenger airbag, lower No. 1 instrument panel airbag and lower No. 2 instrument panel airbag are designed to supplement seat belts in the event of a front collision in order to help reduce shock to the head, chest and knees of the driver and front passenger. This system is a 3-sensor type airbag system which detects the impact during a front collision using the center airbag sensor and front airbag sensors. It also operates the airbag system and seat belt pretensioners. This vehicle is equipped with electrical-type deceleration sensors for the front airbags in order to detect details about the extent of a collision during the initial stages of the collision. Therefore, the deployment of the driver airbag and instrument panel passenger airbag is controlled in two stages according to the severity of the impact. In conjunction with the impact absorbing structure for a side collision, the front seat side airbag and curtain shield airbag are designed to help reduce shock to the driver, front passenger and rear outer passengers in the event of a side collision. The curtain shield airbag helps reduce shock to the front and rear seat occupants. In conjunction with the curtain shield airbag, side airbag sensors are installed at the bottom of the front doors and rear airbag sensors are installed at the bottom of the rear pillars. In this system, a front side collision is detected by the side airbag sensor in order to simultaneously deploy the front seat side and curtain shield airbags. A rear side collision is detected by the rear airbag sensor and the center airbag sensor in order to deploy the curtain shield airbag. The center airbag sensor sends the airbag deployment signal to the ECM through the CAN (Controller Area Network) to operate the fuel pump control. The center airbag sensor sends the airbag deployment signal to the main body ECU via the discrete line to operate collision door lock release control.
2. CONSTRUCTION AND OPERATION FRONT AIRBAG SENSOR The front airbag sensors are installed on the right and left radiator supports respectively. The front airbag sensor consists of a deceleration sensor. The deceleration sensor is built into the front airbag sensor and the distortion that is created in the sensor is converted into an electric signal based on the vehicle deceleration rate during a front collision. Accordingly, the extent of the initial collision can be detected in detail. SIDE AIRBAG SENSOR The side airbag sensors are installed on the bottom of the right and left front doors respectively. The side airbag sensor consists of a deceleration sensor. The deceleration sensor is built into the side airbag sensor and the distortion that is created in the sensor is converted into an electric signal based on the vehicle deceleration rate during a front side collision. Accordingly, the extent of the initial collision can be detected in detail. REAR AIRBAG SENSOR The rear airbag sensors are installed on the right and left rear pillars respectively. The rear airbag sensor consists of a deceleration sensor. The deceleration sensor is built into the rear airbag sensor, and the distortion that is created in the sensor is converted into an electric signal based on the vehicle deceleration rate during a rear side collision. Accordingly, the extent of the initial collision can be detected in detail. REAR FLOOR SIDE AIRBAG SENSOR The rear floor side airbag sensor is installed in the center of the floor between the rear pillars. The rear floor side airbag sensor consists of a deceleration sensor. The deceleration sensor is built into the rear floor side airbag sensor and the distortion that is created in the sensor is converted into an electric signal based on the vehicle deceleration rate during a side collision. Accordingly, the extent of the initial collision can be detected in detail. CENTER AIRBAG SENSOR General The center airbag sensor is installed in the center floor under the instrument panel. The center airbag sensor consists of a deceleration sensor, safing sensor, electronic safing sensor, ignition control circuit and diagnostic circuit. The center airbag sensor receives signals from the deceleration sensor and safing sensor built into the center airbag sensor and front airbag sensor. Then, the center airbag sensor determines whether the steering pad, instrument panel passenger airbag, lower No. 1 instrument panel airbag, lower No. 2 instrument panel airbag and front seat belt pretensioners should be activated, and diagnoses system malfunctions. The center airbag sensor causes the front seat side airbags and curtain shield airbags to deploy when receiving signals from the side airbag sensors. The center airbag sensor receives signals from the deceleration sensor and the electronic safing sensor built into the center airbag sensor and the rear airbag sensor, determines whether the curtain shield airbag should be activated and diagnoses system malfunctions. The center airbag sensor sends the airbag deployment signal to the ECM through the CAN to operate the fuel pump control. The center airbag sensor sends the airbag deployment signal to the main body ECU through the discrete line to operate collision door lock release control. Deceleration sensor and ignition control circuit The deceleration sensor is built into the center airbag sensor. The ignition control circuit performs calculations based on the signal output from the deceleration sensors of the center airbag sensor and front airbag sensor. If the calculated values are more than the specified values, it activates an ignition operation. Safing sensor The safing sensor is built into the center airbag sensor. During a front collision, the sensor turns on and outputs an on signal to the center airbag sensor if a deceleration rate sent to the safing sensor is more than the specified value. Electronic safing sensor The electronic safing sensor is built into the center airbag sensor. During a side collision, the sensor turns on and outputs an on signal to the center airbag sensor if a deceleration rate sent to the electronic safing sensor is more than the specified value. Backup power source The backup power source consists of a power supply capacitor and DC-DC converter. When the power system does not function during a collision, the power supply capacitor discharges and supplies electric power to the system. The DC-DC converter operates as a boosting transformer when the battery voltage falls below a predetermined level. Diagnostic circuit This circuit constantly diagnoses system malfunctions. When a malfunction is detected, it turns on the SRS warning light in the combination meter to inform the driver. Memory circuit When a malfunction is detected in the diagnostic circuit, it is coded and stored in the memory circuit. SRS WARNING LIGHT The SRS warning light is located in the combination meter. It comes on to inform the driver of system trouble when a malfunction is detected in the self-diagnosis of the center airbag sensor. Under normal operating conditions when the ignition switch is turned to ON, it comes on for approximately 6 seconds and then goes off.
3. DEPLOYMENT CONDITION If the vehicle is in a collision and the shock is more than the specified value, the SRS is activated automatically. The center airbag sensor includes the safing sensor and deceleration sensor. The safing sensor is designed to turn on at a lower deceleration rate than the deceleration sensor. The center airbag sensor determines whether ignition is necessary based on signals from the deceleration sensor and the front airbag sensor. If the safing sensor turns on simultaneously, current flows to the squibs to deploy the SRS as shown in the illustration below. HINT: In case of a front collision, the ignition signal may be output with the deceleration sensor on signal even without a signal from the front airbag sensor. The center airbag sensor determines whether ignition is necessary based on signals from the side airbag sensor. If the safing sensor turns on simultaneously, current flows to the squib to deploy the SRS as shown in the illustration below. The center airbag sensor determines whether ignition is necessary based on signals from the side airbag sensor and rear airbag sensor. If the safing sensor turns on simultaneously, current flows to the squib to deploy the SRS as shown in the illustration below. The center airbag sensor determines whether ignition is necessary based on signals from the rear airbag sensor. If the safing sensor turns on simultaneously, current flows to the squib to deploy the SRS as shown in the illustration below. HINT: If the front seat side airbag deploys, the curtain shield airbag will also deploy, regardless of whether the signal is output from the rear airbag sensor.

CHECK MODE PROCEDURE

Note. Enter "Signal Check" from the "DTC Check" screen displayed on the Techstream to clear the output DTCs (both present and past).

HINT

1. DTCs can be stored more sensitively in check mode than in normal diagnosis mode.
2. Perform the check mode inspection when a malfunction in each squib circuit is suspected even after the normal system code is output through normal diagnosis mode inspection.

1. CHECK MODE PROCEDURE (Using the Techstream) Turn the ignition switch off. Connect the Techstream to the DLC3. Turn the ignition switch to ON. Turn the Techstream on. Select "Signal Check" and proceed with checking using the Techstream.