NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/rec/autos/tech/17760

Internet Message Format | 1993-01-12 | 1.6 KB

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Newsgroups: rec.autos.tech
Subject: Re: 88 Spectrum Turbo, CHECK ENGINE light occasionally ? How to.
Date: 12 Jan 1993 11:12:26 -0600
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    "How do I check the codes on this type of car?"

This really should be a FAQ.  GM cars, the codes read out via the check engine
light.  With the ignition off, jumper the diagnostic terminal to ground.  This
means connecting terminals A and B on the ALDL connector together.  The
connector is under the dash, usually near the fuse box.  A and B are the two
rightmost pins in the top row, if you're looking at it so the key molding is at
the top of the connector.  Turn the key to "ON".  The ECM will flash a code 12
three times, followed by any stored trouble codes (each also three times),
followed by 12 again.  This cycle repeats until you turn the ignition off or
start the car.  The codes are indicated by counting.  I.e., "12" is "flash,
pause, flash flash, long pause".

To erase the codes, disconnect the ECM memory power.  This is usually separate
from the ECM's Vcc, so you either need to find the right place (on my car it's
the inline fuel pump fuse under the hood) or disconnect the battery (which will
also kill your radio memory).  I.e., removing the "ECM" fuse at the fuse block
probably *won't* work.

Or just get a copy of Diacom, plug it in, and read the codes right off your PC
screen.

            - Michel

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