On 1991-93 vehicles equipped with an automatic transaxle, the Powertrain Control Module (PCM) stores a parameter called oil life left percent. This is used by the computer to illuminate the SERVICE ENGINE SOON light when the percent reaches a minimum level, and to inform a technician that the transmission fluid is in need of a change. If a suitable scan tool is available, connect it and reset the parameter to 100 percent by accessing the special test function. If you do not have access to a suitable scan tool as described in Emission Controls of this guide, the vehicle should be taken to a dealer or shop that has the appropriate tool. Simply tell them that the transmission oil has just been changed and the oil life PCM parameter needs to be reset.