This article relates to 1993 till 1995 J30/J30t's with OBD1.
The ECU is located behind the front passenger kick panel, located in the passenger footwell.
Here are the instructions for reading the LED light located on the ECU. The number of blinks correspond to the trouble codes below.
If a malfunction occurs within the ECU/fuel injection system, a diagnostic trouble code may be stored in the ECU and the ‘‘Check Engine’’ lamp will blink. There is also a lamp built into the ECU which will concurrently blink. To read Code output, proceed as follows:
1. Turn ignition On, but do not start engine.2. Using a small screwdriver, turn diagnostic mode selector switch, located on side of ECU, fully clockwise.3. Wait two seconds, then rotate switch to full counterclockwise position.4. A malfunction code can be read as the long (0.6 second) blink, indicating the first digit of a two digit number and the short (0.3 second) blink, indicating the second digit.
Ensure that the diagnostic switch is to the full counterclockwise position whenever the vehicle is in use.
Once you have the numeric code, here is what they mean:
11 Crank Angle Sensor12 Mass Air Flow Sensor13 ECT Sensor14 Vehicle Speed Sensor16 TCS Signal21 Ignition Signal Circuit25 Idle Air Control Valve22 Fuel Pump Control31 ECM32 EGR Function33 Heated Oxygen Sensor34 Knock Sensor35 EGR Temperature Sensor (RH)41 Intake Air Temperature Sensor42 Fuel Temp Sensor43 Throttle Position Sensor45 Injector Leak46 Secondary Throttle Sensor51 Injector Analysis53 EGR Temperature Sensor (LH)54 Signal Circuit From A/T Control Unit To ECM65-71 Single Cylinder Or Multiple Cylinder Misfire72 Three Way catalyst Function76 Fuel Injection System Function77 Rear Heated Oxygen Sensor82 Crankshaft Position Sensor84 A/T Diagnosis Communication Line91 Front Heated Oxygen Sensor Heater103 Park/Neutral Position Switch105 EGR & Canister Control Solenoid