Step by step guide on how to retrieve and decode Isuzu OBD1 trouble codes for vehicles older than 1995.
Difficulty Scale: 2 of 10
Begin with the vehicle on level ground with the engine "OFF" and the parking brake set..
Step 1 - To retrieve codes locate the data port connector which is under the dash or the drivers or passengers side or under the hood near the battery or firewall. Once the connector is located use a jumper wire to connect the "A' and "B" terminals.
Step 2 - Next, turn the ignition key to the "ON" position (do not start the engine). The check engine light will start blinking; the first set of blinks will be the first number of the trouble code. Then a short pause will occur and the second code number will follow. For an example if the check engine light blinks three times and then a short break and then blinks two time the code number will be 32.
Step 3 - To restart the code gathering process turn the ignition key to the "OFF" position and then back "ON" again. To clear diagnostic trouble codes once the repair has been made remove the negative battery cable for thirty seconds and reconnect.
Trouble Code Table
Code 12 System normal
Code 13 Oxygen sensor fault
Code 14 Coolant temperature fault
Code 21 TPS signal fault
Code 23 MAT circuit fault
Code 24 Vehicle speed signal sensor fault
Code 32 EGR sensor fault
Code 23 MAP sensor fault
Code 42 Electronic spark timing fault
Code 43 Electronic spark control fault
Code 44 Oxygen sensor fault
Code 51 Prom error
Code 55 ECM fault
All Isuzu cars and light truck are equipped with the OBD1 computer system (before 1996). The system triggers trouble codes once the computer system has malfunctioned. These codes will present themselves as two digit codes and can be read at the check engine light which is similar the the GM style of OBD1 code gathering.