Displaying & Reading Trouble Codes

NOTE: This is the only information provided by the manufacturer for reading diagnostic trouble codes for this system.

PRE-CHECK

1. DIAGNOSIS SYSTEM
a. Description
- When troubleshooting OBD II vehicles, the only difference from the usual troubleshooting procedure is that you need to connect to the vehicle an OBD II scan tool complying with SAE J1987 or LEXUS hand-held tester, and read off various data output from the vehicle's ECM.




- OBD II regulations require that the vehicle's on- board computer lights up the Malfunction Indicator Lamp (MIL) on the instrument panel when the computer detects a malfunction in the computer itself or in the drive system components which affect the vehicle emissions. In addition to the MIL lighting up when a malfunction is detected, the applicable DTCs prescribed by SAE J201 2 are recorded in the ECM memory.
If the malfunction only occurs in 3 consecutive trips, the MIL goes off but the DTCs remain in the ECM memory.
- To check the DTCs, connect the OBD II scan tool or the LEXUS hand-held tester to DLC3 of the vehicle. The OBD II scan tool or LEXUS hand-held tester also enables you to erase the DTCs and check freeze frame data and various forms of engine data (For instruction book).




- The DTCs include SAE controlled codes and Manufacturer controlled codes. SAE controlled codes must be set as the codes prescribed by the SAE, while Manufacturer controlled codes can be set freely by a manufacturer within the prescribed limits (See the DTC chart).
- The diagnosis system operates in the normal mode during the normal vehicle use, and also has a check mode for technicians to simulate malfunction symptoms and perform troubleshooting. Most DTCs use 2-trip detection logic (*) to prevent erroneous detection. By switching the ECM to the check mode when troubleshooting, the technician can cause the MIL to light up for a malfunction that is only detected once or momentarily (LEXUS hand-held tester).
- *2 trip detection logic:
When a malfunction is first detected, the malfunction is temporarily stored in the ECM memory.
If the same malfunction is detected again during the second test drive, this second detection causes the MIL to light up.







b. Inspect 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.

HINT: If your display shows UNABLE TO CONNECT TO VEHICLE when you have connected the cable of OBD II scan tool or LEXUS hand-held tester to DLC3, turned the ignition switch ON and operated the scan tool, there is a problem on the vehicle side or tool side.

- If the communication is normal when the tool is connected to another vehicle, inspect DLC3 on the original vehicle.
- If the communication is still impossible when the tool is connected connected to another vehicle, the problem is probably in the tool itself, so consult the Service Department listed in the tool's instruction manual.




2. Normal Mode:
INSPECT DIAGNOSIS
a. Check the MIL.
1. The MIL comes on when the ignition switch is turned ON and the engine is not running.

HINT: If the MIL does not light up, troubleshoot the combination meter.

2. When the engine is started, the MIL should go off. If the lamp remains on, it means that the diagnosis system has detected a malfunction or abnormality in the system.

b. Check the DTC.

NOTE:
LEXUS hand-held tester only:
When the diagnostic system is switched from normal mode to check mode, all the DTCs and freeze frame data recorded in the normal mode will be erased. So before switching modes, always check the DTCs and freeze frame data, and note them down.
1. Prepare an OBD II scan tool (complying with SAE J1978) or LEXUS hand-held tester.




2. Connect the OBD II scan tool or LEXUS hand-held tester to the DLC3 at the lower of the instrument panel.
3. Turn the ignition switch ON and push the OBD II scan tool or LEXUS hand-held tester switch ON.
4. Use the OBD II scan tool or LEXUS hand-held tester to check the DTCs and freeze frame data and note them down (For operating instructions, see the OBD II scan tool's instruction book).
5. See to confirm the details of the DTCs.

NOTE: When simulating symptoms with an OBD II scan tool (excluding LEXUS hand-held tester) to check the DTCs, use the normal mode. For codes on the DTCs chart subject to "2-trip detection logic", turn the ignition switch OFF after the symptoms is simulated once. Then repeat the simulation process again. When the program has been simulated twice, the MIL is indicated on the instrument panel and the DTCs are recorded in the ECM.

3. Check Mode:
INSPECT DIAGNOSIS

HINT: LEXUS hand-held tester only:
Compared to the normal mode, the check mode has more sensitive ability to detect malfunctions. Furthermore, the same diagnostic items which are detected in the normal mode can also be detected in the check mode.

a. Check the DTC.
1. Check the initial conditions.
- Battery positive voltage 11 V or more.
- Throttle valve fully closed.
- Transaxle in P position.
- Air conditioning switched OFF.

2. Turn the ignition switch OFF.
3. Prepare a LEXUS hand-held tester.




4. Connect the LEXUS hand-held tester to the DLC3 at the lower of the instrument panel.
5. Turn the ignition switch ON and push the LEXUS hand-held tester switch ON.




6. Switch the LEXUS hand-held tester from the normal mode to the check mode (Check that the MIL flashes).
7. Start the engine (MIL goes off after the engine starts).
8. Simulate the conditions of the malfunction described by the customer.

NOTE: Leave the ignition switch ON until you have checked the DTCs, etc.

9. After simulating the malfunction conditions, use the LEXUS hand-held tester diagnosis selector to check the DTCs and freeze frame data, etc.

HINT: Take care not to turn the ignition switch OFF, as turning it OFF the diagnosis system from the check mode to the normal mode, which erases all the DTCs, etc.

10. After checking the DTC, inspect the applicable circuit.

b. Clear the DTC.
When operating an OBD II scan tool (complying with SAE J1978) or TOYOTA hand-held tester to erase the codes, the DTCs and freeze frame date will be erased (See the OBD II scan tool's instruction book for operating instructions.).

NOTE: If the LEXUS hand-held tester switches the ECM from the normal mode to the check mode or vice-versa, of if the ignition switch is turned from ON to ACC or OFF during check mode, the DTCs and freeze frame data will be erased.

4. PROBLEM SYMPTOM CONFIRMATION
Taking into consideration the results of the customer problem analysis, try to reproduce the symptoms of the trouble. If the problem is that the transaxle does not up-shift, down-shift, or the shift point is too high or too low, conduct the road test to confirm the automatic shift schedule and simulate the problem symptoms.