Proper Tools and Testing Procedures

Never substitute a Transmission controller from a previous year, as they are not interchangeable.

Prior to disconnecting any control module, make sure the ignition is OFF. Failure to do so could damage the module.

When testing voltage or continuity at the EATX controller connector, use the terminal side (not the wire end).

Probing a wire through the insulation will damage it and eventually cause it to fail because of corrosion.

Be careful not to spread the terminals when probing connectors.


Use care to prevent accidental shorting of terminals during tests. Such mistakes can damage fuses or components. Also, a second fault message could be set, making diagnosis of the original problem more difficult.

Use scan tool internal voltmeter (when possible, unless otherwise instructed by procedure to use an "external" voltmeter.

CAUTION: Never use a test lamp in place of a voltmeter.