How to Check the Alternator Opel Vectra A

Alternator, Check

The check can be carried out in assembled condition as well as on the test stand. The check here described is for vehicles in assembled condition, which can be applied analogously to the test stand.

A charged battery is required for this check.

Note the following safety measures:

1. Negative terminals of battery, alternator and regulator must match.

2. Never allow the alternator to run on an uncontrolled open circuit.

3. Never short the terminals to alternator and regulator.

4. Do not reverse polarity of alternator.

5. If an auxiliary battery (e.g. as a booster battery) is connected, always ensure that the same battery terminals are connected with each other.

6. When using a charger to charge the battery, connect charger connection leads with the correct battery terminals.

Disconnect the ground cable when charging.

Alternator output

Circuit diagram

1 Load resistor, set parallel to battery

2 Battery

3 Voltmeter

4 Ammeter

5 Ignition lock

6 Charge telltale

7 Alternator

8 Charge telltale relay

Disconnect battery.

Close off connecting cable from alternator terminal "B+".

Set ammeter (measuring range 100 A) in disconnected line.

Connect battery.

Connect controllable load resistor to battery terminal.

Set resistor to "0" before connecting; connect lead first to battery then to resistor.

Connect tachometer.

Connect oscilloscope according to manufacturer's instructions.

Start engine and read off resulting current at various engine speeds.

Alternator output

Adjust load resistor, if the required load currents are not attained.

Ensure that the voltage does not sink below 13.5 V.

The voltage lines on the oscilloscope should be regular.

Do not short-circuit battery with resistor.

Start engine.

Bosch alternator:

Adjust load resistor, until ammeter shows the prescribed value

Read off regulated voltage - test value, see Technical Data.

Only check alternator with parallel switching, charged battery, switch off load resistor and battery after alternator standstill.

Disconnection of load without parallel switching battery leads to voltage transients, which can lead to damage to the alternator diodes.