Tachometer: Description and Operation

How the Circuit Works
The gauge assembly receives battery voltage at all times through fuse 56 and through fuse 20 with the ignition switch in ON (II) or START (III). The gauge assembly also receives battery voltage through fuse 55 and the gauge relay with the ignition switch in ON (II) or START (III).

Tachometer
The tachometer drive circuit receives pulses at the rate of three pulses per engine revolution from the powertrain control module (PCM). The pulse frequency increases as the engine speed increases. This speed signal is converted and displayed by the tachometer.

WARNING: Do not smoke while working on the fuel system.
Keep open flame away from the work area. Drain fuel only into an approved container.