Tachometer: Testing and Inspection
INSPECT TACHOMETER ON-VEHICLEa. Connect a tune-up test tachometer, and start the engine.
NOTE: Reversing the connection of the tachometer will damage the transistors and diodes inside.
b. Compare the tester reading with tachometer reading.
RPM (DC 13.5 V, 25 °C (77 °F))
( ): Reference
If the indicated value is out of the allowable range, replace the combination meter.
INSPECT TACHOMETER RESISTANCE
Measure the resistance between terminals with an ohmmeter at the positions shown in the illustration.
If resistance value is not as specified, replace the combination meter.