Section 249 (Air Conditioning System (Diagnosis)): Pre-Check

WARNING: This page is about a different car, the 2003 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.

DTC CHECK USING LEXUS HAND-HELD TESTER
1. Hook up the LEXUS hand-held tester to the DLC3.
2. Read the diagnostic trouble codes by following the prompts on the tester screen.
  Please refer to the LEXUS hand-held tester operator's manual for further details.
  
  Fig 1: Checking DTC Using Lexus Hand-Held Tester
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
CLEARING DTC
1. Pull out the ECU-B1 fuse in engine room J/B for 10 sec. or longer to clear diagnostic the DTC's memory.
2. After reinserting the fuse, check that the normal code is output.
  
  Fig 2: Identifying ECU-B1 Fuse
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
ACTUATOR CHECK
1. Connect the LEXUS hand-held tester to the DLC 3.
2. Turn the ignition switch to ON and LEXUS hand-held tester main switch ON.
3. Select the ACTIVE TEST mode on the LEXUS hand-held tester.
4. Check the temperature and air flow visually and manually.
  
  Fig 3: Temperature And Air Flow Conditions Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

CHECK DLC3

The vehicle's ECM uses the ISO 9141 -2 communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 9141 -2 format.

Fig 4: Locating DLC3 Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

DLC3 CONNECTOR TERMINALS REFERENCE

Terminal No.	Connection/Voltage or Resistance	Condition
7	Bus + Line/Pulse generation	During transmission
4	Chassis Ground <=> Body Ground/1 Ω or less	Always
5	Signal Ground <=> Body Ground/1 Ω or less	Always
16	Battery Positive <=> Body Ground/9 - 14 V	Always

DATA LIST

HINT:

According to the DATA LIST displayed by LEXUS hand-held tester, you can read the value of the switch, sensor, actuator and so on without parts removal. Reading the DATA LIST as a first step of troubleshooting is one of the method to shorten the labor time.

Connect the LEXUS hand-held tester to the DLC3.
Turn the ignition switch ON.

According to the display on tester, read the "DATA LIST".

DATA LIST REFERENCE

Item	Measurement Item/ Display (Range)	Normal Condition	Diagnostic Note
A/C MAG CLUTCH	A/C magnet clutch status/ ON or OFF	A/C SW Push: ON A/C SW Release: OFF	<=>

ACTIVE TEST

HINT:

Performing the ACTIVE TEST using LEXUS 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.

Connect the LEXUS hand-held tester to the DLC3.
Turn the ignition switch ON.

According to the display on tester, read the "ACTIVE TEST".

ACTIVE TEST REFERENCE

Item	Test Details	Diagnostic Note
A/C MAG CLUTCH	Control the A/C magnet clutch ON/OFF	-