Test M: Tachometer Reads Too High, Too Low Or Erratic

Turn ignition off. Remove instrument cluster. See REMOVAL & INSTALLATION  . Leave connectors connected. Set voltmeter on AC scale. Start engine and allow to idle. Connect voltmeter between ground and instrument cluster connector C272, pin No. 4 (Green/White wire). See Figure . Increase engine speed while observing voltmeter. See TACHOMETER VOLTAGE TABLE. If voltage readings are as specified, replace instrument cluster. If voltage readings are not as specified, problem is in Powertrain Control Module (PCM). See TESTS W/CODES article in ENGINE PERFORMANCE section.