Checking Error Codes

FOR 87-89....


The easiest and cheapest way to check for ECU error codes is to go to Radio Shack and buy a 12v LED for about $2.50.

Once you have your LED, it's best to solder aligator clips onto each wire. I've heard you can go without them, but I've never got it to work without them.

Once you have your LED ready to roll, it's time to test for codes. I was surprised as to how easy it was to check for these.

Open the glove box, and squeeze the sides to drop it all the way down. Get down and look up and you will see a white/yellowish colored plug with nothing plugged into it. Take the LED and hook the red lead up to the most upper right terminal, and the black lead to the most lower left terminal. Once you have done this, you're just about done. Just start the car, or turn the key to the "On" position.

If there are any errors, the LED will blink a certain amount of times. The amount of blinks determines the error. For example, 1 blink then a pause, then one blink again, is code #1. 3 blinks, then a pause, then 3 blinks, again, and so on and so forth, is code #3. Note - It will always give you a code 1 (o2 sensor) until the car warms up, and the car must be started to test this.

Here are the codes:
1 - o2 Sensor
2 - Ignition pulse
3 - MAS
4 - n/a
5 - TPS
6 - ISC
7 - Engine coolant temp sensor (two prongs, not one)

After you've checked the codes, and fixed whatever was wrong, unplug the battery for a minute to reset your ECU. Hope this helps.

FOR 86 AND PRIOR...


Position the self-diagnosis 3 pin connector located by the air can near the fuel pump check connector (its is not the round ignition terminal like the 88-89 ones its actually a round 3 pin like it for checking ecu error codes), make it so the single pin is at the top and the double pins are at the bottom.
Connect voltmeter or the LED light!!! positive to upper single pin (signal, light blue+yellow wire). Connect negative to lower right pin (ground, black wire). FYI - lower left pin (white wire) is O2 sensor diagnosis connector.
*The rest is all the same as far as code numbers and the flashes*