Displaying & Reading Trouble Codes
NOTE: This is the only information provided by the manufacturer for reading Diagnostic Trouble Codes for this system. TOYOTA does not provide a procedure for reading diagnostic trouble codes without a scan tool.PRE-CHECK
1. DIAGNOSIS SYSTEM
a. Description
- When troubleshooting OBD II vehicles, the only difference from the usual troubleshooting procedure is that you connect the OBD II scan tool complying with SAE J1978 or TOYOTA hand-held tester to the vehicle, 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 MIL on the instrument panel when the computer detects a malfunction in the computer itself or in 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 J2021 are re corded in the ECM memory.
If the malfunction does not reoccur in 3-trips, the MIL goes off but the DTCs remain recorded in the ECM memory.
- To check the DTCs, connect the OBD II scan tool or TOYOTA hand-held tester to DLC3 on the vehicle.
The OBD II scan tool or the TOYOTA hand-held tester also enables you to erase the DTCs and check freezed frame data and various forms of engine data. (For operation instructions, see the OBD II scan tool's instruction book.)
- DTCs include SAE controlled codes and Manufacturer controlled codes. SAE controlled codes must be set as prescribed by the SAE, while Manufacturer controlled codes can be set freely by the Manufacturer within the prescribed limits.
- The diagnosis system operates in normal mode during 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 check mode when troubleshooting, the technician can cause the MIL to light up for a malfunction that is only detected once or momentarily. (TOYOTA hand-held tester) (See step 3.)
- *2-Trip detection logic:
When a logic 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 V.P.W. (Variable Pulse Width) for communication to comply with SAE J1850. The terminal arrangement of DLC3 complies with SAE J1962 and matches the V.P.W. format.
HINT: If your display shows "UNABLE TO CONNECT TO VEHICLE" when you have connected the cable of the OBD II scan tool or the TOYOTA 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 communication is normal when the tool is connected to another vehicle, inspect DLC3 on the original vehicle.
- If communication is still not possible 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.
2. INSPECT DIAGNOSES (NORMAL MODE)
a. Check the MIL.
1. The MIL lights up when the ignition switch is turned ON and the engine dose not run.
HINT: If the MIL does not light up, troubleshoot the combination meter.
2. When the engine starts, the MIL should go off.
HINT: If the lamp remains on, the diagnosis system has detected a malfunction or abnormality in the system.
b. Check the DTC.
NOTE: (TOYOTA hand-held tester only):
When the diagnostic system Is switched from normal mode to check mode, it erases all DTCs and freezed frame data recorded in normal mode. So before switching modes, always check the DTCs and freezed frame data, and note them down.
1. Prepare the OBD II scan tool (complying with SAE J1978) or the TOYOTA hand-held tester.
2. Connect the OBD II scan tool or the TOYOTA hand- held tester to DLC3 at the lower portion of the instrument panel
3. Turn the ignition switch ON and turn the OBD II scan tool or the TOYOTA hand-held tester switch ON.
4. Use the OBD II scan tool or the TOYOTA hand-held tester to check the DTCs and freezed frame data. Note them down. (For operating instructions, see the OBD II scan tool's instruction book.)
5. See Trouble Code Descriptions to confirm the details of the DTCs.
NOTE: When the simulating symptoms with an OBD II scan tool (excluding the TOYOTA hand-held tester) to check the DTCs, use normal mode. For codes on the DTC chart subject to "2-trip detection logic", turn the ignition switch off after the symptoms have been in simulation process again. When the program has been simulated twice, the MIL lights up and the DTCs are recorded in the ECM.
3. INSPECT DIAGNOSIS (CHECK MODE)
HINT: TOYOTA hand-held tester:
Compared to the normal mode, the check mode has high sensing 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. Initial conditions
- Battery positive voltage 11 V or more
- Throttle valve fully closed
- Transaxle in the PARK position
- Air conditioning switched off
2. Turn the ignition switch OFF.
3. Prepare the TOYOTA hand-held tester.
4. Connect the TOYOTA hand-held tester to DLC3 at the lower portion of the instrument panel.
5. Turn the ignition switch ON and switch the TOYOTA hand-held tester ON.
6. Switch the TOYOTA hand-held tester from normal mode to check mode. (Check that the MIL flashes.)
7. Start the engine. (The MIL goes off after the engine start.)
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 TOYOTA hand-held tester diagnosis selector to check the DTCs and freezed frame data, etc.
HINT: Take care not to turn the ignition switch OFF, turning the ignition switch off switches the diagnosis system from check mode to normal mode, so all DTCs, etc. are erased.
10. After checking the DTC, inspect the applicable circuit.
b. Clearing the DTC.
The following action will erase the DTCs and freezed frame data.
Operating the OBD II scan tool (complying with SAE J1978) or the TOYOTA hand-held tester to erase the codes. (See the OBD II scan tool's instruction book for operating instructions.)
NOTE: If the TOYOTA hand-held tester switches the ECM from normal mode to check mode or vise-versa, or if the ignition switch is turned from ON to ACC or OFF during check mode, the DTCs and freezed frame data will be erased.