How To Retrieve Toyota OBD I Diagnostic Trouble Codes

Retrieving the trouble codes on your OBD I Toyota Corolla isn't difficult. In this tutorial I'll explain how you can do it in a step-by-step way.

Checking to see what trouble code is lighting up the check engine light (malfunction indicator light -MIL) is done by jumpering together the TE1 and E1 terminals of the Data Link Connector (DLC) with a jumper wire (with the Key On Engine Off).

Once the jumper wire is installed, the malfunction indicator light (MIL) will start flashing the trouble codes stored in the fuel injection computer's memory.

Contents of this tutorial at a quick glance:

  1. Reading The On/Off Flashes Of The Check Engine Light.
  2. Location Of The Diagnostic Link Connector (DLC).
  3. Toyota OBD I Diagnostic Trouble Code Definitions.

En Español You can find this tutorial in Spanish here: Cómo Leer Los Códigos OBD I (1990-1995 1.6L Toyota Corolla) (at: autotecnico-online.com).

Reading The On/Off Flashes Of The Check Engine Light

Reading the On/Off Flashes of the Check Engine Light (How to Retrieve Toyota OBD I Diagnostic Trouble Codes)

As mentioned at the beginning, your OBD I Toyota Corolla flashes the malfunction indicator light (MIL -also known as the check engine light CEL) once you have jumpered terminals TE1 and E1 in the diagnostic link connector (DLC).

The DLC is located on the left strut tower in the engine compartment. To see a photo of the DLC, go to:

  1. Location Of The Diagnostic Link Connector (DLC)).

These are the steps to retrieve the trouble codes:

  1. Make sure your battery is fully charged before starting (its customary to place a charger on the battery while retrieving trouble codes to keep the battery from discharging).
  2. Turn the key to the On position but don't start the vehicle.
  3. Jumper terminals TE1 and E1 of the diagnostic link connector in the engine compartment.
  4. Count the number of flashes of the malfunction indicator light (MIL).
  5. If no trouble codes are present:
    1. The MIL will flash continuously and evenly (see illustration below).
  6. If trouble codes are present:
    1. The MIL will flash the trouble codes in a specific pattern.
    2. The digits of the trouble code will be flashed at about 1/2 (.5) second intervals. A 1 1/2 (1.5) second pause will separate first and second digits of the code (see illustration above).
    3. If more than one trouble code is stored, a 2 1/2 (2.5) second pause will separate the next flashed trouble code.
    4. Once all trouble codes are flashed. a 4 1/2 (4.5) second pause will occur. After this 4.5 second pause, the trouble codes will be repeated.
    5. Trouble codes are flashed in order of smallest to largest number.

Once you've confirmed and written down the trouble codes, remove the jumper wire from the diagnostic link connector (DLC) and turn the key to the Off position.


Reading the On/Off Flashes of the Check Engine Light (How to Retrieve Toyota OBD I Diagnostic Trouble Codes)

Location Of The Diagnostic Link Connector (DLC)

Reading the On/Off Flashes of the Check Engine Light (How to Retrieve Toyota OBD I Diagnostic Trouble Codes)

The diagnostic link connector (DLC) on your Toyota Corolla is located in the engine compartment. More specifically, it's attached to the left-side strut tower (see image above).