Diagnosis System [10/2018 - 07/2022]

1. When troubleshooting On-Board Diagnostic (OBD II) vehicles, an OBD II scan tool (complying with SAE J1978) must be connected to the vehicle. Various data output from the vehicle TCM can then be read.
2. OBD II regulations require that the vehicle on-board computer illuminate the Malfunction Indicator Lamp (MIL) on the instrument panel when the computer detects a malfunction in any of the following:
   Fig 1: Identifying Malfunction Indicator Lamp

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   • The emission control system/components
   • The powertrain control components which affect vehicle emissions
   • The computer

   In addition, the applicable Diagnostic Trouble Codes (DTCs) prescribed by SAE J2012 are stored in the TCM memory.

   If a malfunction does not recur, the MIL remains illuminated until the engine switch is turned off, and the MIL turns off when the engine is started. However, the DTCs will remain recorded in the TCM memory.

3. To check for DTCs, connect the Techstream to the Data Link Connector 3 (DLC3) of the vehicle. The Techstream displays DTCs, freeze frame data and a variety of engine data.

   The DTCs and freeze frame data can be cleared with the Techstream.

   Refer to DTC CHECK / CLEAR [10/2018 - 07/2022] 

1. The diagnosis system operates in normal mode during normal vehicle use. In normal mode, 2-trip detection logic is used to ensure accurate detection of malfunctions. Check mode is also available to technicians as an option. In check mode, 1-trip detection logic is used when reproducing malfunction symptoms for increasing the ability of the system to detect malfunctions, including intermittent malfunctions.

1. When a malfunction is first detected, the malfunction is temporarily stored in the TCM memory (1st trip). If the same malfunction is detected during the subsequent driving cycle, the MIL is illuminated (2nd trip).

1. The TCM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was moving or stationary, whether the engine was warmed up or not and whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
2. The Techstream displays freeze frame data recorded at five different points: 1) 3 times before the DTC is stored, 2) once when the DTC is stored, and 3) once after the DTC is stored. The data can be used to reproduce the vehicle condition around the time of the malfunction. The data may be helpful in determining the cause of a malfunction. It may also be helpful in determining whether a DTC is being caused by a temporary malfunction.
   Fig 2: Identifying Freeze Frame Data Graph

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Powertrain > Transmission 

1. Check the DLC3.

   Refer to GENERAL INFORMATION [10/2018 - ]

Standard Voltage

11 to 14 V

If the voltage is below 11 V, recharge or replace the auxiliary battery.

1. The MIL is illuminated when the engine switch is turned on (IG) (with the engine not running).

   If the MIL does not illuminate, check the MIL circuit.

   Refer to MIL Circuit [10/2018 - 07/2022]

2. The MIL will turn off when the engine is started. If the MIL remains illuminated, the diagnosis system has detected a malfunction or abnormality in the system.