Lexus IS250 IS220d GSE20 ALE20 - SUPPLEMENTAL RESTRAINT SYSTEM
AIRBAG SYSTEM - DIAGNOSIS SYSTEM
| CHECK DLC3 |
The vehicle's ECM uses CAN and conforms to ISO 14230 and ISO 9141-2 for communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and meets the ISO 14230 and ISO 9141-2 format.
| Symbols (Terminal No.) | Terminal Description | Condition | Specified condition |
| SIL (7) - SG (5) | Bus "+" line | During transmission | Pulse generation |
| CG (4) - Body ground | Chassis ground | Always | Below 1 Ω |
| SG (5) - Body ground | Signal ground | Always | Below 1 Ω |
| BAT (16) - Body ground | Battery positive | Always | 11 to 14 V |
| CANH (6) - CANL (14) | HIGH-level CAN bus line | Engine switch off | 54 to 67 Ω |
| CANH (6) - Battery positive | HIGH-level CAN bus line | Engine switch off | 1 MΩ or higher |
| CANH (6) - CG (4) | HIGH-level CAN bus line | Engine switch off | 3 MΩ or higher |
| CANL (14) - Battery positive | LOW-level CAN bus line | Engine switch off | 1 MΩ or higher |
| CANL (14) - CG (4) | LOW-level CAN bus line | Engine switch off | 3 MΩ or higher |
- HINT:
- If the display shows a communication error message when connecting the cable of the intelligent tester to the DLC3, turning the engine switch on (IG) and operating the intelligent tester, there is a problem on the vehicle side or tester side.
| SYMPTOM SIMULATION |
- HINT:
- The most difficult case in troubleshooting is when no symptoms occur. In such cases, a thorough customer problem analysis must be carried out. Then the same or similar conditions and environment in which the problem occurred in the customer's vehicle should be reproduced. No matter how experienced or skilled a technician may be, if he proceeds to troubleshoot without confirming the problem symptoms, he will likely overlook something important and make a wrong guess at some points in the repair operation.
- This leads to a standstill in troubleshooting.
Vibration method: When vibration seems to be the major cause.
- HINT:
- Perform the simulation method only during the primary check period (for approximately 6 seconds after the engine switch is turned on (IG)).
Slightly vibrate the part of the sensor considered to be the problem cause with your fingers and check whether the malfunction occurs.
- HINT:
- Shaking the relays too strongly may result in open relays.
Slightly shake the connector vertically and horizontally.
Slightly shake the wire harness vertically and horizontally.
The connector joint and fulcrum of the vibration are the major areas to be checked thoroughly.
| FUNCTION OF SRS WARNING LIGHT |
Primary check.
Turn the engine switch off. Wait for at least 2 seconds, then turn the engine switch on (IG). The SRS warning light comes on for approximately 6 seconds and the diagnosis of the airbag system (including the seat belt pretensioners) is performed.
- HINT:
- If trouble is detected during the primary check, the SRS warning light remains on even after the primary check period (for approximately 6 seconds) has elapsed.
Constant check.
After the primary check, the center airbag sensor assembly constantly monitors the airbag system for trouble.
- HINT:
- If trouble is detected during the constant check, the center airbag sensor assembly functions as follows:
Review.
When the airbag system is normal:
The SRS warning light comes on only during the primary check period (for approximately 6 seconds after the engine switch is turned on (IG)).
When the airbag system has trouble:
- HINT:
- The center airbag sensor assembly keeps the SRS warning light on if the airbag has been deployed.
| SRS WARNING LIGHT CHECK |
Turn the engine switch on (IG), and check that the SRS warning light comes on for approximately 6 seconds (primary check).
Check that the SRS warning light goes off approximately 6 seconds after the engine switch is turned on (IG) (constant check).
- HINT:
- When any of the following symptoms occur, refer to the "Problem Symptoms Table" .
| FUNCTION OF PASSENGER AIRBAG ON/OFF INDICATOR |
Turn the engine switch on (IG).
The passenger airbag ON/OFF indicator ("ON and OFF") comes on for approximately 4 seconds, then goes off for approximately 2 seconds.
Approximately 6 seconds after the engine switch is turned on (IG), the passenger airbag ON/OFF indicator will be ON/OFF depending on the conditions listed below.
- HINT:
- If the passenger airbag ON/OFF indicator do not operate as specified in the following tables according to the manual cut off switch status, and the SRS warning light is off, no DTC will be output. Therefore, perform troubleshooting for "Trouble in passenger airbag ON/OFF indicator" .
| Manual Cut OFF Switch | Passenger Airbag ON/OFF Indicator | SRS Warning Light | |
| ON Indicator | OFF Indicator | ||
| ON | ON | OFF | OFF |
| OFF | OFF | ON | OFF |
| Switch failure | OFF | ON | ON |
| PASSENGER AIRBAG ON/OFF INDICATOR CHECK |
Turn the engine switch on (IG).
Check that the passenger airbag ON/OFF indicator ("ON" and "OFF") comes on for approximately 4 seconds, then goes off for approximately 2 seconds.
- HINT:
- Refer to the table in step 5regarding the passenger airbag ON/OFF indicator when the engine switch is turned on (IG) and approximately 6 seconds pass.
| ACTIVATION PREVENTION MECHANISM |
FUNCTION OF ACTIVATION PREVENTION MECHANISM
An activation prevention mechanism is built into the connector (on the center airbag sensor assembly side) of the airbag system squib circuit to prevent accidental airbag activation.
This mechanism closes the circuit when the connector is disconnected by bringing the short spring into contact with the terminals and shutting off external electricity to prevent accidental airbag activation.
RELEASE METHOD OF ACTIVATION PREVENTION MECHANISM
To release the activation prevention mechanism, insert a piece of paper with the same thickness as the male terminal (approximately 0.5 mm (0.020 in.)) between the terminals and the short spring to break the connection.
Refer to the following illustrations concerning connectors utilizing the activation prevention mechanism and its release method.
- CAUTION:
- Never release the activation prevention mechanism on the squib connector even when inspecting with the squib disconnected.
- NOTICE:
