I drive an 89 dodge dynasty and the electrical system has not been working. The battery has been tested and works fine and i have tried two different alternators. However when i go up to autozone the battery tester says that the alternator is not working(voltage not high enough). I have checked the connections to both the battery and alternator and both look normal. (side note: when i put a charged battery into the car and start it, it runs fine the only problem is the electrical system.)
I honestly don’t know what else to do to fix my car, if anyone can advise i would greatly appreciate it.
You can’t check the battery connections by looking at them. You need to remove the cables from the battery (negative first!) and physically clean them. There are inexpensive tools for this job. Remember that the cables have at least two ends each.
2 different OLD alternators or 2 brand new ones? Either way, you won’t fix this yourself unless you own your won volt-ohm meter and learn how to use it. (they are cheap!) Relying on the counter monkey at AdvancedAutoPepReilly to test and then recommend repairs will not fix the car but it will spend your money. Take it to a proper independent repair shop for diagnosis and expect to pay for the diagnosis.
If you are ready to step up, we are ready to help. Engine off voltage across the battery terminals should be about 12.4 V or more. If not, charge the battery and test again. Engine running voltage across the terminals should be 13.5 volts or more. If they are not, the alternator is bad or the wiring from the alternator is bad.
by checking the connections i meant that i looked over all of them and there were no breaks in the sheilding or the cables themselves. I will clean them thankyou
Measure the voltages of the field terminals (blue and green wires) of the alternator when the engine is running, also the voltage of the output terminal of the alternator and post the results.
i tried two different new alternators. I own a voltmeter and the voltage across the battery is normal around 12.8. i took it to autozone becouse they usually are able to give a bit of advice and there tests are free. I was not expecting a magic fix just a starting point.
the car runs fine once it is started except the voltage is constantly dropping as i drive. becouse the only problem i have with the car is the voltage draining as i drive i said that the only problem is with the electical system.
If the alternator tests OK when removed from the car and there’s no problem with the wiring yet the battery loses charge you might consider this as a solution
your car has the voltage regulator incorporated into the engine computer but a new computer will be expensive and possibly difficult to find but wiring in a conventional regulator as shown in the link is a very common repair. In fact there are numerous regulators made just for that situation.
First I would remove the battery cables (both ends) and clean up the mating surfaces.
It could also be that the drive belt is too loose to spin the alternator fast enough.
If the terminals are clean and tight and the belt is tight as it should be…with the engine running, check the voltage at the output lug on the alternator and the negative battery terminal.
You should see at least 13.5 volts at idle. No need to drive around the block for this test.
In order for the alternator to work correctly it requires the exciter circuit to have power getting to it. Most charging systems use the charge warning light circuit to supply power to the exciter inside the alternator. So for that to happen the warning light needs to work when the ignition is turned ON. Make sure that the light turns on when the ignition is ON and the engine isn’t running. If that is good then start the engine and turn on the headlights to high and the blower to full speed. Then measure the voltage between the output lead of the alternator and the positive side of the battery. If the wire connection is good the voltage drop across the wire connection should be less than 0.3 volts. You should also check the voltage between the case ground of the alternator and the negative post of the battery. There should be very little voltage across there if the grounding is good.