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W-Body Performance - Pushrod / DOHC
TTs - Computer Dignostics (OBDI)

"When you're sick of staring at that Service Engine Light!"


Ok, so we all hate our Service Engine Light going off and we hate when something goes wrong... but that doesn't mean we have to pay several hundred dollars to find out what's broken.  This tips benifits the most when the car is acting up; basically the comupter tell us what is not functioning correctly.  Many small time machanics, including myself and other do-it-yourselfers find this to be the easiest way to generally isolate a sensor problem on 1988 - 1994+ vehicles.

Looking the connection veritcally up towards the sky (if you were laying in the car) where the top of the picture is towards the firewall, the two ports that need to be connected are the bottom left.  For some other models they could be any other position, but they be always be side-by-side together.

1.)  Locate the dignostic connection under the driver side dash; it's a black plastic box that could be on either side of the steering column
2.)  Turn the ignition to the "on" position without the car running
3.)  Unfold a paper clip and complete the circuit with the two ports that are next to each other (see photo)
4.)  Once circuit is closed (paper clip is in both ports) you'll hear the radiator fans turn on and you will see the Service Engine Light begin to blink on the instrument panel; the SES light will blink once, pause, and then blink twice to start off.  The number of blinks equals the number corresponding to the digit  (example above in step 4 would be code #12, code #12 means ECM works properly)
5.)  To determine fault code, let the computer cycle through code #12 three times; afterwards the blinks will be indicating current fault code in the system
6.)  When all fault code are shown and continuously repeating, pull out paper clip to stop process; shut off ignition
7.)  Check service maunal for what code number coressponds with faulty circuit / sensor
8.)  To delete codes after repair work, pull negative battery cable for about 5 - 10 minutes

- Average Time:  5+ minutes
- Scheduled Maintenace:  whenever the Service Engine Light is on
- Written by Erik Melander