Powertrain Management: Tools and Equipment

Analog Volt/Ohm Meter:

CAUTION: When connecting a voltmeter or ammeter to a circuit, make sure polarity is correct to avoid damaging the meter and/or circuit.

PURPOSE
Like digital meters, analog Volt/Ohm Meters (VOM's), can be used to measure actual circuit values for comparison with expected circuit values.

ADVANTAGES OF ANALOG METERS OVER DIGITAL METERS
Analog Meters are especially useful when checking the output voltage or resistance of potentiometers, (i.e. throttle positions sensors), because the output voltage or resistance can be observed as a smooth sweep of the needle.

- It is difficult or impossible to see a jump in resistance or voltage using a Digital Volt/Ohm Meter (DVOM).

VOLTMETER CONNECTION:
When measuring voltage always connect the voltmeter in parallel to the circuit or component.

CAUTION: Connecting a voltmeter in series with a circuit may damage the meter and/or circuit.

OHM METER CONNECTION:
Before attempting to measure the resistance of a circuit or component, always disconnect any voltage sources from the circuit or component.
Connect the ohmmeter across--in parallel with--the resistance to be measured.

CAUTION: Connecting an ohmmeter to a circuit while voltage is present may damage the meter and/or the circuit.

AMMETER CONNECTION:
Connect the ammeter in series with the circuit.

CAUTION: Make sure polarity is correct prior to energizing circuit.