Test G: Tachometer Inaccurate

Turn ignition switch to LOCK position. Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. On vehicles equipped with 4.0L engine, measure resistance between ground and instrument cluster White 10-pin harness connector C288 terminal No. 8 (Black/Yellow wire). See Figure . On vehicles equipped with 5.0L engine, measure resistance between ground and instrument cluster White 16-pin harness connector C286 terminal No. 16 (Black/White wire). See Figure . On all models, if resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Black/White or Black/Yellow wire between instrument cluster and ground. Recheck system operation.

Measure resistance of printed circuit between tachometer pins (in center of clips) and corresponding instrument cluster connector terminals. See TACHOMETER PRINTED CIRCUIT CHECK table. If all resistance measurements are less than 5 ohms, replace tachometer. See GAUGES under REMOVAL & INSTALLATION. Recheck system operation. If any measurement is more than 5 ohms, replace instrument cluster printed circuit. See PRINTED CIRCUIT under REMOVAL & INSTALLATION. Recheck system operation.

TACHOMETER PRINTED CIRCUIT CHECK

Tachometer Pin

⁽¹⁾ Instrument Cluster Connector (Terminal No.)

"B"

White 16-Pin Connector C286 (13)

Lower "G"

White 16-Pin Connector C287 (2)

Upper "G"

White 16-Pin Connector C286 (16)

4.0L

⁽²⁾

5.0L

White 16-Pin Connector C286 (12)

"S"

White 16-Pin Connector C286 (15)

⁽¹⁾	See Figure , Figure and Figure .

⁽²⁾	Resistance value measured between instrument cluster White 10-pin harness connector C288 terminal No. 8 and Upper "G" is 3900-4700 ohms.

Check Clean Tach Output (CTO) circuit for open or short. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If CTO circuit is okay, replace tachometer. Recheck system operation. If CTO circuit has open or short, replace PCM. Recheck system operation.