Section 292 (Body Control System - Diagnosis): Pre-Check

WARNING: This page is about a different car, the 2004 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.

DIAGNOSIS SYSTEM
1. Description
  ECU data of this system can be read from DLC3 of the vehicle.
  
  Therefore when there seems to be a trouble on this system, use hand-held tester to check and troubleshoot it.
  
  Fig 1: Connecting Hand-Held Tester To DLC3
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Check the DLC3.
The vehicle's ECM uses ISO 9141-2 for communication. The terminal arrangement of DLC3 complies with SAE J1962 and matches the ISO 9141-2 format.

Fig 2: Identifying DLC3 Terminals
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 3: DLC3 Terminals Reference Table
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

If the display shows "UNABLE TO CONNECT TO VEHICLE" when the cable of the hand- held tester is connected to DLC3, the ignition switch is turned ON and the hand- held tester is operated, there is a problem either on the vehicle side or the tool side.
- If communication is normal when the tool is connected to another vehicle, inspect DLC3 on the original vehicle.
- If communication does not function when the tool is connected to another vehicle, the problem is probably in the tool itself, so consult the Service Department listed in the tool's instruction manual.
USING HAND-HELD TESTER
1. Hook up the hand-held tester to the DLC3.
2. Monitor the ECU data by following the prompts on the tester screen.
HINT:

Hand-held tester has a "Snapshot" function which records the monitored data. Please refer to the hand-held tester operator manual for further details.
DTC CLEAR
DTC and the freeze frame data can be erased by operating the hand-held tester.
DATA LIST
HINT:

By the DATA LIST displayed on the hand-held tester, you can read the value of the switch, sensor, actuator and so on without removing any parts. Reading the DATA LIST as a first step of troubleshooting is one of the method to shorten the labor time.
1. Connect the hand-held tester to DLC3.
2. Turn the ignition switch ON.
3. According to the display on tester, read the "DATA LIST".
1. Body ECU (Main)
  Power source & ignition switch:
  
  Fig 4: Data List (Power Source & Ignition Switch)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Key unlock warning switch:
  
  Fig 5: Data List (Key Unlock Warning Switch)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Door courtesy switch:
  
  Fig 6: Data List (Door Courtesy Switch)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Headlight dimmer switch:
  
  Fig 7: Data List (Headlight Dimmer Switch)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Light control switch:
  
  Fig 8: Data List (Light Control Switch)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Door key lock and unlock switch:
  
  Fig 9: Data List (Door Key Lock And Unlock Switch)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Parking brake switch:
  
  Fig 10: Data List (Parking Brake Switch)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Driver seat buckle switch:
  
  Fig 11: Data List (Driver Seat Buckle Switch)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Seat memory switch:
  
  Fig 12: Data List (Seat Memory Switch)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  DRL relay circuit:
  
  Fig 13: Data List (DRL Relay Circuit)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Door lock control:
  
  Fig 14: Data List (Door Lock Control)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Wireless door lock control:
  
  Fig 15: Data List (Wireless Door Lock Control)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Wireless door lock buzzer:
  
  Fig 16: Data List (Wireless Door Lock Buzzer)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Light control sensor:
  
  Fig 17: Data List (Light Control Sensor)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Illumination:
  
  Fig 18: Data List (Illumination)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Park / Neutral position switch:
  
  Fig 19: Data List (Park / Neutral Position Switch)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Alternator signal:
  
  Fig 20: Data List (Alternator Signal)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Others:
  
  Fig 21: Data List (Others)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Body ECU (Sub)
Power source & ignition switch:

Fig 22: Data List (Power Source & Ignition Switch)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Park / Neutral position switch:

Fig 23: Data List (Park / Neutral Position Switch)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Wiper switch:

Fig 24: Data List (Wiper Switch)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
ACTIVE TEST
HINT:

Performing the ACTIVE TEST using the hand-held tester allows the relay, VSV, actuator and so on to operate without parts removal. Performing the ACTIVE TEST as a first step of troubleshooting is one of the method to shorten the labor time.

It is possible to display the DATA LIST during the ACTIVE TEST.
1. Connect the hand-held tester to the DLC3.
2. Turn the ignition switch ON.
3. According to the display on tester, perform the "ACTIVE TEST".
  1. Body ECU (Main)
    
    Fig 25: Active Test Chart - Body ECU (Main)
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. Body ECU (Sub)
Fig 26: Active Test Chart - Body ECU (Sub)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002