Inspection Procedure

WARNING: This page is about a different car, the 2004 Lexus ES 330. However, it is still accessible from the selected car via links, so may be relevant.

READ VALUE OF HAND-HELD TESTER (TRANSPONDER KEY ECU (SWITCH CONDITION))
1. Connect the hand-held tester to the DLC3.
2. Turn the ignition switch to the ON position, and turn the hand-held tester main switch ON.
3. Select the item "KEY SW" in the DATA LIST, and read its value displayed on the hand-held tester.
  Standard:
  - ON: Key is in ignition key cylinder
  - OFF: No key is in ignition key cylinder
  Result:
  
  Fig 1: Transponder Key ECU (Switch Condition) Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
A: REPLACE TRANSPONDER KEY ECU ASSY

B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE (See PROBLEM SYMPTOMS TABLE )

C: Go to next step.
INSPECT UN-LOCK WARNING SWITCH ASSY
1. Remove the unlock warning switch.
  
  Fig 2: Removing Unlock Warning Switch
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the unlock warning switch resistance.
  Standard
  
  Fig 3: Unlock Warning Switch Assy Condition Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NG: REPLACE UN-LOCK WARNING SWITCH ASSY

OK: Go to next step.
CHECK HARNESS AND CONNECTOR (TRANSPONDER KEY ECU - UN-LOCK WARNING SWITCH)
1. Disconnect the T20 ECU and U1 switch connectors.
  
  Fig 4: Disconnecting T20 ECU & U1 Switch Connectors
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance between the wire harness side connectors.
  Standard
  
  Fig 5: Transponder Key ECU Unlock Warning Switch Condition Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step.
CHECK HARNESS AND CONNECTOR (UN-LOCK WARNING SWITCH - BODY GROUND)
1. Disconnect the U1 switch connector.
  
  Fig 6: Disconnecting U1 Switch Connector
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Check the resistance between the wire harness side connector and the body ground.
  Standard
  
  Fig 7: Checking Resistance Between Terminal U1 & Body Ground Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: REPLACE TRANSPONDER KEY ECU ASSY