Ammeter Diagnosis

Ammeter Diagnosis

The accuracy of an ammeter may be determine by comparing indications with those of a test ammeter of known accuracy.

1. Turn ignition switch off.
2. Disconnect battery positive cable from terminal on starter motor solenoid.

Caution: Test ammeter must be an actual ammeter, not a voltmeter with a calibrated ammeter scale. Connecting a voltmeter is services will destroy its internal circuitry.

3. Connect test ammeter is series between solenoid terminal and disconnected cable.
4. Turn ignition switch to On position. Do not start engine. Turn headlamps on. Turn heater blower motor to high speed.
5. Compare current flow (amps) indication of test ammeter with that of ammeter installed in vehicle.
6. Turn headlamps and heater blower motor off. Start engine and operate at high idle. Compare current flow (amps) indication of test ammeter with that of ammeter installed in vehicle.
7. Replace ammeter if current flow (amps) indications of vehicle ammeter and test ammeter vary more than calibration tolerance listed in Specifications.