Just try a jumper wire and get your codes from the check engine light.
Jump from the single wire gray connector to the big test connector like below. The yellow wire is the jumper wire.
Turn your ignition to the on position and start counting flashes of the Check Engine light.
If you don't at least get an 11, there may be something wrong with your ECM or ECM relay.
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351W 89 Mustang GT Convertible
[This message has been edited by jimberg (edited 08-16-2001).]