Vauxhall Workshop Service and Repair Manuals

Alternator, Check  

  Inspect   

This check can be made with the alternator installed or on the test stand.  

Preconditions for test when installed:  

Battery fully charged.  

V-belt and V-belt tension OK.  

Ground connections alternator-engine-body-battery OK.  

Battery terminals in good condition (not oxidised, not broken, not loose).  

  Important!   

Do not reverse polarity of alternator terminals. Do not short-circuit alternator terminals. Do not allow alternator to run with battery disconnected (may destroy the diodes). When checking the alternator on a test stand, remove vacuum pump (no lubrication)  

  Inspect   

Circuit diagram for checking alternator output     1  Load resistor (switched parallel to battery)   2  Battery   3  Voltmeter   4  Ammeter   5  Ignition lock   6  Charge telltale   7  Alternator   8  Relay, charge control       Disconnect ground cable from battery.   Disconnect connecting cable from alternator terminal "B+" and switch ammeter (4) (range 100 A) between alternator "B+" and disconnected lead.     Important!    Do not short-circuit battery with resistor (1).

  Inspect   

Set regulatable load resistor to "infinite" and connect in parallel to battery at positive and negative terminals.   Connect tachometer.   Connect oscilloscope according to manufacturer's instructions.   Connect ground cable to battery.   Start engine and read off current and voltage at different engine speeds.   Test Values   Increase engine speed to 4000 rpm. The battery voltage must adjust to 14.4 V to 15.0 V within one minute.   Engine speed   Min. alternator output.   2100 rpm   48 A   3500 rpm   65 A

 

If the required load currents are not attained, adjust load resistance.   The shape of the voltage curves on the oscilloscope should be uniform (see illus.).   If the required minimum current values are not attained, or if the oscilloscope shows peaks or troughs, the alternator should be overhauled or replaced.