Tachometer Test
- Remove tachometer. Start engine. Using voltage meter, test voltage between Pins No. 3 and 4. See Fig 1. See TACHOMETER TERMINAL IDENTIFICATION . If battery voltage is OK, go to next step. If not OK, check wiring.
- With engine running check Pin No. 1 for a pulse signal. The engine speed produces 3 pulses per revolution. Example: 1,000 rpm is approximately 50 pulses per second. A voltage reading of 3 volts will show that a pulse is being sent to tachometer. If OK, replace tachometer. If not OK, check wire circuit from PCM.
TACHOMETER TERMINAL IDENTIFICATION
| Cavity | Terminal Identification |
|---|---|
| 1 | Tachometer Pulse Signal |
| 2 | Illumination Feed |
| 3 | Ground |
| 4 | Ignition Feed |