Re: Alternator is broken. Think it is the brushes. How do...
Not recomended for amatuers. You'll need a set or tamper-proof sockets and bits. Generally it's just easy to replace the entire alternator than to repair or service an older one. They tend to come apart a little more than you intended.
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Hi Charles
I haven't seen an Alternator with a Fuse.
They Generate 35-55 or more Amps and are usually connected directly to the Battery Positive. Check at Alt. Main Terminal with MultiMeter. Check for Good Ground.
The small wire on the back of the alternator often comes from Ignition Key + to control the charge rate.
The Modern Alt. also has an internal Regulator Circuit to control charge rate.
If trying to save money.... Alternators can be split open on the Bench and repaired. Just put a mark across joint before opening.
Use a brush hook (make one) to hold brushes back while re assembling.
Items to watch for:
Brushes Worn Out - no juice to Rotor to excite (generate)
Diodes Blown - (Multimeter Test on Diode Function for shorts / open. Simple Unsolder, Press out & replace
Regulator Blown - Buy replacement
Stator Coils Corroded or Shorted/Open or bad solder joints.
On motors/generators (starter, alternator, etc,) the brushes make the connection to the rotating armature. You can read up a little on motors and generators. Bottom line is, the brush terminals provide the access point for the outside world - to electrical leads. If you think of an electric drill for something simple...power is applied to the brush terminals, the brushes connect that power to the multiple rotor points as it spins. Slightly different system with DC power but the brushes serve same basic function - providing an electrical contact to something rotating. You may be dealing with a starter or alternator where faulty (worn) brushes or faulty brush terminal wiring is stopping power from getting to the starter, or from the alternator. Does that help at all?
Hi, the actual output voltage produced by the alternator will vary depending on temperature and load, but will typically be about 1-1/2 to 2 volts higher than battery voltage. At idle, most charging systems will produce 13.8 to 15.3 volts with no lights or accessories on. This can be measured by connecting the positive (+) and negative (-) test leads of a voltmeter to the battery posts while the engine is running.
Possible cause of the alternator not charging includes Slipping or broken alternator belt, Open diode, Open circuit in stator windings, Open charging circuit, Open field circuit, Worn brushes or slip ring and Defective voltage regulator..
There is a fusible link in the connection between the alternator and the positive battery cable connector.
On the 1997 it is a 175 Amp Mega Fuse mounted on the outside of the high voltage fuse box located on the drivers's side in the engine compartment. After replacing the battery and the Alternator, it turned out to be a $4.99 fuse that was keeping the alternator current from reaching the battery.
The alternator cable bolts on to one end of the fuse, and the positive battery cable bolts on to the other end. You can test it inline without removing it by checking for continuity across the two bolts. An open circuit indicates that the fuse is blown and needs to be replaced.
If the fuse is blown (which means you have an open circuit), the battery light in the dash should be on.
The car will start normally if the battery has enough of a charge, but it will eventually die when the battery is too depleted to keep the car running, because the alternator can't take over if the current doesn't make it across the blown fuse.
If the battery is dead, it will start with a jump start, but it will die shortly after you remove the jumper cables for the same reason.
This is one of those problems that you might not think of right away, and it will drive you out of your mind. ALWAYS check this fuse before replacing a battery or an alternator on a mid to late '90s Model Thunderbird. You will save time, money, and you won't pull out your hair.
OK I think you have two unrelated issues here. The first is the coolant sensor. Either the sensor is broken or, just as likely, there is a problem with the wires going to and from it, either broken or the insulation has broken causing a short. When the coolant sensor malfunctions it can send a signal to engine control unit (ECU) that the coolant, and therefore the engine, is cold. The ECU responds by injecting more fuel to compensate for a 'cold' engine and this causes the engine to race. Fix the coolant sensor/wiring and the engine racing will also be cured.
The charging voltage from the alternator is too high in my experience. It should be only be about 14.5 volts even when the battery is low. Most alternators have an integrated brushes and electronic module that can be unbolted and exchanged for a new one. Failing that, an alternator can be bought at a reasonable price on exchange for your old one. Some damage to other electrical systems my result of high voltage supply, my car actually has an over voltage protection relay and fuse to protect the ABS braking system and other circuits. A friendly consultation with an auto electrician now might save money on other things in future
Replace the Alternator.
Sounds like the internal brushes have worn out as you appear to have the correct feeds to it.
If you are tempted to open the alt to have a look at the brushes, be careful as incorrect assembly can cause serious damage as can incorrect re-assembly. You can simply replace the brushes but I would advise against it as the copper rings the brushes rub on (the slip rings) will also be worn and require replacement, this is difficult if you do not have the experience. Also, the bearings should also be replaced as they will no doubt be worn too. Altogether a specialist job, so grab yourself an new or exchange alternator. if you have to get a second hand unit, have it tested BEFORE you fit it..
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