Diagnosis System

WARNING: This page is about a different car, the 2010 Lexus GS 450h. However, it is still accessible from the selected car via links, so may be relevant.

CHECK DLC3

The ECU uses ISO 15765-4 for communication. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 15765-4 format.

Fig 1: Identifying DLC3 Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Symbols (Terminal No.)	Terminal Description	Condition	Pulse 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	10 to 14 V
CANH (6) - CANL (14)	CAN bus line	Power switch OFF*	54 to 69 Ω
CANH (6) - BAT (16)	HIGH-level CAN bus line	Power switch OFF*	6 kΩ or higher
CANH (6) - CG (4)	HIGH-level CAN bus line	Power switch OFF*	200 Ω or higher
CANL (14) - BAT (16)	LOW-level CAN bus line	Power switch OFF*	6 kΩ or higher
CANL (14) - CG (4)	LOW-level CAN bus line	Power switch OFF*	200 Ω or higher

NOTE:

*: Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the power switch, any other switches, or the doors.

If the result is not as specified, the DLC3 may have a malfunction. Repair or replace the harness and connector.

HINT:

Connect the cable of the Techstream to the DLC3, turn the power switch ON (IG) and attempt to use the Techstream. If the display indicates that a communication error has occurred, there is a problem either with the vehicle or with the Techstream.

If communication is normal when the Techstream is connected to another vehicle, inspect the DLC3 of the original vehicle.
If communication is still not possible when the Techstream is connected to another vehicle, the problem is probably in the Techstream itself. Consult the Service Department listed in the Techstream's instruction manual.

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 the environment in which the problem occurred in the customer's vehicle should be simulated. No matter how experienced or skilled a technician may be, if he proceeds to troubleshooting 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.
1. Vibration method: When vibration seems to be the major cause.
  
  Fig 2: Identifying Vibration Method
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  HINT:
  
  Perform the simulation method only during the primary check period (for approximately 6 seconds after the power switch is turned ON (IG)).
  1. 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.
  2. Slightly shake the connector vertically and horizontally.
  3. 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 PASSENGER AIRBAG ON/OFF INDICATOR

Initial check:

Turn the power 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 power switch is turned on (IG), the passenger airbag ON/OFF indicator will show ON or OFF depending on the conditions listed below.

Condition	ON Indicator	OFF Indicator
Vacant	OFF	OFF
Adult is seated	ON	OFF
Child is seated	OFF	ON
Child restraint system is set	OFF	ON
Occupant classification system failure	OFF	ON

HINT:

The passenger airbag ON/OFF indicator is based on the timing chart below in order to check the indicator light circuit.
When the occupant classification system has trouble, both the SRS warning light and the passenger airbag ON/OFF indicator ("OFF") come on. In this case, check the DTCs in "AIRBAG SYSTEM" first.

Fig 3: Identifying Passenger Airbag On/Off Indicator - Timing Chart

CHECK PASSENGER AIRBAG ON/OFF INDICATOR
1. Turn the power switch ON (IG).
  
  Fig 4: Identifying Passenger Airbag On/Off Indicator
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. 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 the previous step regarding the passenger airbag ON/OFF indicator when the power switch is turned ON (IG) and approximately 6 seconds pass.