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OBD-I: Reading Your Codes

JiFaire

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I have good news: Since your truck is a 1994 or 1995, that means it has an OBD-I computer. You don't need a fancy-dan code reader to check your codes, just a paper-clip or jumper wire.

Under your steering column, you have an ALDL plug that looks like the attached picture. With the key off, take a metal paper clip (or another suitable jumper wire) and place the ends in holes A and B. Get a piece of paper and pencil handy, watch the SES light on your dash (beside the speedometer), and turn the key to the ON position. The SES light should start flashing.

flash-(pause)-flash-flash-(long pause) ... that's a code 12.

All DTC codes will be repeated 3 times. Write them down as they come up. For instance, you could get:

17-18-35-36-71

That means you have codes 17, 18, 35, 36, and 71

When you're done, and the codes are all written down, clear them by pushing the brake and accelerator pedals to the floor, hold them for 15 seconds, let them up, push them down again, hold, and turn the key off.

Turning the key on again should get you only a repeating code 12 (all is well).

Shut the key off, remove the jumper.

NEVER put the jumper in or take it out with the key on!!
 

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