Component Tests: Tachometer
CAUTION:
Tachometer is a solid-state device that will be damaged if resistance is checked. When replacing tachometer, DO NOT reverse wiring connections. Tachometer's transistors and diodes will damaged if wiring connections are reversed. Be careful not to drop tachometer or subject it to severe shock.
Ensure ambient temperature is at least 77°F (25°C) and there are 13.5 volts at tachometer input power supply terminal. Connect a scan tool to data link connector, or an external tachometer to engine. Start engine and allow to idle. Compare scan tool or external tachometer readings with instrument cluster tachometer readings. Replace tachometer if gauge readings are not within acceptable limits. See TACHOMETER TEST LIMITS table.
TACHOMETER TEST LIMITS
| Application & Engine RPM (1) | Acceptable Range (RPM) | ||
|---|---|---|---|
| 1000 | 900-1100 | ||
| 2000 | 1850-2150 | ||
| 3000 | 2800-3200 | ||
| 4000 | 3800-4200 | ||
| 5000 | 4800-5200 | ||
| 6000 | 5750-6250 | ||
| 7000 | 6700-7300 | ||
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