Question about BMW 325
Start the car and then pull the pos battery cable if the car dies its your alternator...their test equipment is only right about 30 percent of the time
Posted on Aug 25, 2008
I don't know if your car has an integrated regulator or not; some house the regulator in a section of the alternator case, others mount it remote from it.
The regulator monitors the load and battery voltag,e primitively but effectively, and controls the current flowing through the field winding of the alternator to ground, changing the magnetic field intensity and consequently the voltage output of the alternator.
The 'hot' end of the field is internally connected to the + output, the 'cold' end is controlled by a transistor inside the regulator which, in turn, is controlled by circuitry monitoring the system voltage.
Some alternators can be tested by sticking a wire through a specified opening, actually shorting the controlled end of the field to ground briefly, while monitoring the voltage across the battery, doing this though for seconds only.
This essentially bypasses a suspected defective regulator; this causes the output voltage to rise instantly to its maximum of ~17 volts if the alternator is OK.
I don't recommend poking a wire at random into an available opening so having a service manual (Haynes-Chilton) would be nearly mandatory.
Posted on Oct 03, 2008
Hi, I can't tell you exactly what is wrong because there is too much involved at this point, what with 2 shops working with it, but I can give you some advise on what else to check. On the alternators and the wiring that supports them a small volt charge is taken off one of the slip rings, where the brushes ride, for the purpose of turning out the light. As I remember, this is a yellow wire that runs back to the dash.
To the alternator, it would be one of the wires that plug into the side of the alternator case.
Posted on Nov 27, 2008
To gain access to the alternator you have first disconnect your battery. After that you need to remove the passenger seat. Then remove the engine access cover and you will be able to remove the alternator and belt.
Posted on Jan 29, 2009
do a continuity test from the large red wire on your alt to the battery,could be a fusible link or broken wire,sometimes a wire will break within the sheathing so it won't be visible by eye,check all conections for corrosion and either clean or repair
Posted on Feb 21, 2009
Did you test the Alternator on or off the truck? It might be a problem with the control system to the Alternator. The regulator need a battery feed to work, It is usually ran through an alternator fuse.
Posted on Mar 11, 2009
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Posted on Jan 02, 2017
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