Isuzu vehicles 1985-1994 obd1 codes retrieval

You can get the check engine light codes yourself on 1985-94 Isuzu vehicles by using a jumper wire between terminal pins 1 and 3 or A and B in the diagnostic connector. This diagnostic connector can be located anywhere from the driver side kick panel, passenger kick panel and sometimes at the center console. When using A and B terminal pins, getting the codes is similar to GM vehicles. Once the jumper wire is connected, turn your key on and read the codes being flashed in the dash panel.

Reading the lights being flashed is simple, like code 12 is a long flash, a pause followed by 2 short flashes. Code 12 is also the first code to appear which verifies that the diagnostic system is working. If there are any codes that are present, it will be flashed in the same way with each codes being flashed 3 times before going to a next higher code.

Clearing the codes is done mostly by removing the battery negative terminal but removing the ecm (computer) fuse for 10 seconds is the best method. This way, you don’t need to re-program your radio or clock in case you use the battery connection.
Don't forget to remove the jumper wire with key off before clearing the codes.

Here are some popular obd1 codes for 1985-94 Isuzu vehicles:

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

Notes:

Codes being displayed will differ from model to model. Sometimes, there are more codes than shown above. If not on the list, please check your service manual or contact ATS.

To prevent replacing unnecessary parts, do not replace any part until you verify the circuit or sensor or contact ATS for assistance.