Inspection Procedure

WARNING: This page is about a different car, the 2004 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.

HINT:

If different DTCs related to different systems are output simultaneously, while terminal E2 is used as a ground terminal, terminal E2 may be open.
Read freeze frame data using the hand-held tester or the OBD II scan tool. Because freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time the malfunction.

Connect OBD II scan tool or hand-held tester, and read value of engine coolant temperature.
PREPARATION:
1. Connect the OBD II scan tool or hand-held tester to the DLC3
2. Turn the ignition switch ON and push the OBD II scan tool or hand-held tester main switch ON.
3. When using hand-held tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II/DATA LIST/ALL DATA/COOLANT TEMP.
CHECK:

Read the temperature on the OBD II scan tool or the hand-held tester.

OK:

Same as the actual intake air temperature.

RESULT:

Fig 1: Temperature Display Chart
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:
- If there is open circuit, the OBD II scan tool or the hand-held tester indicates -40°C (-40°F).
- If there is short circuit, the OBD II scan tool or the hand-held tester indicates 140°C (284°F) or more.
1. B: Go to step 4 .
2. C: Check for intermittent problems (See PRE-CHECK ).
3. A: Go to next step.
Check for open in harness or ECM.
PREPARATION:
1. Disconnect the engine coolant temperature sensor connector.
2. Connect the sensor and wire harness terminals together.
3. Turn the ignition switch ON.
  
  Fig 2: Turning Ignition Switch To ON
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
4. When using hand-held tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II/DATA LIST/ALL/COOLANT TEMP.
CHECK:

Read the temperature on the OBD II scan tool or the hand-held tester.

OK:

Temperature value: 140°C (284°F) or more
1. OK: Confirm good connection at sensor, If OK, replace engine coolant temperature sensor.
2. NG: Go to next step.
Check for open in harness or ECM.
PREPARATION:
1. Remove the ECM hood (See ENGINE CONTROL MODULE (ECM) ).
2. Connect terminals THA and E2 of the ECM connector.
  
  Fig 3: Connecting Terminals THA & E2 Of ECM Connector
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  HINT:
  
  The engine coolant temperature sensor connector is disconnected. Before checking, do visual and contact pressure check for the ECM connector (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).
3. Turn the ignition switch ON.
4. When using hand-held tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II/DATA LIST/ALL/COOLANT TEMP.
CHECK:

Read the temperature on the OBD II scan tool or the hand-held tester.

OK:

Temperature value: 140°C (284°F) or more
1. OK: Open in harness between terminal E2 or THW, repair or replace harness.
2. NG: Confirm good connection at ECM. If OK, replace ECM (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).
Check for short in harness and ECM.
PREPARATION:
1. Disconnect the mass air flow meter connector.
2. Turn the ignition switch ON.
  
  Fig 4: Turning Ignition Switch To ON
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. When using hand-held tester, enter the following menus: DIAGNOSIS/ENHANCED OBD II/DATA LIST/ALL/COOLANT TEMP.
CHECK:

Read the temperature on the OBD II scan tool or the hand-held tester.

OK:

Temperature value: -40°C (-40°F)
1. OK: Repair or replace harness or connector.
2. NG: Go to next step.
Check for short in harness or ECM.
PREPARATION:
1. Remove the ECM hood (See ENGINE CONTROL MODULE (ECM) ).
2. Disconnect the E4 and E5 connectors from the ECM.
  
  Fig 5: Disconnecting E4 & E5 Connectors From ECM
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  HINT:
  
  The engine coolant temperature sensor connector is disconnected.
3. Turn the ignition switch ON.
4. When using hand-held tester, enter the following menus: DIAGNOSIS/ENHANCED OBD II/DATA LIST/ALL/COOLANT TEMP.
CHECK:

Read the temperature on the OBD II scan tool or the hand-held tester.

OK:

Temperature value: -40°C (-40°F)
1. OK: Repair or replace harness or connector
2. NG: Replace ECM (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).