What is the exciter terminal on an alternator?
The exciter wire is used to turn on the voltage regulator. This wire, when unplugged, should have approx. 12.5 volts with the key on. If it does not then the alternator will not work.
What causes an alternator to undercharge?
In most cases of undercharging, the alternator may have an incorrect diameter pulley installed, the drive belt may be slipping or the alternator itself might be undercapacity for the vehicle application.
Can an alternator cause a short?
As youngfarmer says, an alternator has a rectifier in it and they can short so the alternator becomes a high amperage dead short from the main output wire to ground. Take that wire off (watch out, it is hot all the time unless you disconnect the batteries!)
Do all alternators have exciter wires?
The alternators on most modern vehicles have internal voltage regulators; therefore, they don’t need an exciter wire to function properly.
What happens if alternator fails while driving?
A bad alternator will result in a discharged (dead) battery and cause a vehicle to not start or run. Alternators are designed to maintain a battery’s charge, not to recharge a dead battery. Your alternator’s job is to maintain a consistent charge on your battery. Draining your car’s battery is not advised.
How do you excite an alternator?
Take a small piece of wire and touch one end of it to the battery alternator terminal. Then touch the other end to the small “R” terminal. (Note: This may create a small spark, which is normal.) Remove the wire and start the vehicle.
Can a weak alternator cause poor engine performance?
When the alternator’s electrical power falls, it can cause a malfunction of these systems, leading to engine failure. Symptoms include a slow down, a failure, a hesitation, and a stalling.
How do you check for short alternator?
Disconnect the big main cable to the alternator and see if the short goes away. If it does, then use your meter to measure the ohms between the alternator post and the alternator case. You should have continuity in one direction and if you switch leads you’ll have no continuity.