FixVault

Component Testing: Tachometer

Connect an external tachometer to engine. Start engine. Compare readings of external tachometer with tachometer gauge in instrument cluster. See TACHOMETER TEST  . If external tachometer RPM is not within cluster tachometer specification range, replace cluster tachometer.

CAUTION: When replacing tachometer, DO NOT  reverse wiring connections or damage to tachometer's transistors and diodes will result.
TACHOMETER TEST (1)

External Tachometer RPM Cluster Tachometer
750 650-850
2000 1900-2100
3000 2850-3150
4000 3800-4200
5000 4750-5250
6000 5700-6300
7000 6650-7350
(1) Tests performed at 77°F (25°C), with 13.5 volts at tachometer input power supply terminal.