Test F: Tachometer Inaccurate

With ignition in OFF position, verify instrument cluster connectors are secure. Remove instrument cluster and leave cluster connected. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. With ignition ON and engine running, verify voltage on terminal No. 6 (Green/White wire) of instrument cluster connector C266B on back of instrument cluster at indicated engine speeds. See Figure. See TACHOMETER SIGNAL VOLTAGES table. If voltages are correct, go to next step. If voltage readings are not correct, refer to appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE, for further information on diagnosing possible VSS or PCM concern.

TACHOMETER SIGNAL VOLTAGES

Engine Speed (RPM)	Voltage
1000	1.69
1500	2.64
2000	3.44
2500	4.50
3000	5.22

Turn ignition off. Remove instrument cluster and disconnect all cluster connectors. Measure resistance between tachometer terminals on back of instrument cluster and instrument cluster harness connector C266B as specified. See PRINTED CIRCUIT TESTING table. If all resistance measurements are less than 5 ohms, replace tachometer. If all resistance measurements are not less than 5 ohms, replace instrument cluster printed circuit. See PRINTED CIRCUIT under REMOVAL & INSTALLATION.

PRINTED CIRCUIT TESTING

Tachometer Terminal	Cluster C266B Terminal No.
"B"	2
"G"	5
"S"	6