Alternator not charging the battery???

[Akrem]

Hey I am just reading and jump on board today, I have a 94 ford Taurus and I got into a accident a couple of weeks ago, but after my Battery went dead I bought a new one and it worked fine for a day and it went dead, then I didn't check the alternator I just bought a new one and it worked fine for a day. Then it went dead again,,then I went and turned my alternator for another one and got another one came to install it and bought a multimeter, it looks like my alternator is not putting out the ampage its supposed to be to charge the battery. Could they be selling me a messed up ALt. or is it a wireing problem. I am confused and sorry to be so short of words..but Its just draining my battery, well I traced down one of the wires that was going under my dash board. I am thinking that there is some kind of condensor sensor under the dash that its hookup to thats not good,,and its not relaying the alternator to turn on. Do you know of any such thing, cause I have tested everything and how many OAMs and so forth. My Question is there such a thing and if so could it have gone out when I crashed and the battery and alternator was fine....Lost in Engine World...

[TomV]

Measure the voltage of the battery when the engine is idling. You should have somewhere around 13.5 volts DC. This indicates that the connections are OK and that the alternator is putting out enough current to charge. The turn on the lights, accessories, AC, put the blower on HI, etc. Use as much electricity as you can muster. The voltage on the battery may dip a bit but should still be on the order of 13.5 volts or so. A reading closer to 12 volts indicates a bad alternator/voltage regulator or perhaps a loose/slipping belt. Check the quality of the cable connections to the battery, alternator and grounds.

If it appears that the alternator is working ok, turn off the engine and then restart it. Check the charging again. I had an alternator that worked when you first turned on the car but when the alternator's voltage regulator got hot it did not work any more on the next restart.

If the alternator is still working, then you have either a bad battery or a current drain in the car's circuitry. I replaced my Taurus' battery only 2 1/2 years after I bought the car. I have gotten into the habit of replacing them every 4 years even if there are no problem symptoms.

Remove the batter cable and let the car set overnight to see if it drains internally. If it does not then the problem is in wiring or an electronic component.

[Akrem]

Originally Posted by TomV

Measure the voltage of the battery when the engine is idling. You should have somewhere around 13.5 volts DC. This indicates that the connections are OK and that the alternator is putting out enough current to charge. The turn on the lights, accessories, AC, put the blower on HI, etc. Use as much electricity as you can muster. The voltage on the battery may dip a bit but should still be on the order of 13.5 volts or so. A reading closer to 12 volts indicates a bad alternator/voltage regulator or perhaps a loose/slipping belt. Check the quality of the cable connections to the battery, alternator and grounds.

If it appears that the alternator is working ok, turn off the engine and then restart it. Check the charging again. I had an alternator that worked when you first turned on the car but when the alternator's voltage regulator got hot it did not work any more on the next restart.

If the alternator is still working, then you have either a bad battery or a current drain in the car's circuitry. I replaced my Taurus' battery only 2 1/2 years after I bought the car. I have gotten into the habit of replacing them every 4 years even if there are no problem symptoms.

Remove the batter cable and let the car set overnight to see if it drains internally. If it does not then the problem is in wiring or an electronic component.

I did and checked all the currents with a multimeter, there are two square black boxes on top of the Radiator, what are those boxes and does Tauruses have Relay switches, if so were are they, this is my second Alternator and I had it tested twice and they say its fine...So I am wondering if I have a bad wireing problem...

[shorod]

Are the two black boxes you are referring to different in size? The larger of the two with a bunch of wires going to it is the Constant Control Relay Module (CCRM). It contains relays for the PCM, low and high speed cooling fans, fuel pump, and A/C clutch. The smaller sensor with just a few wires is probably the front airbag sensor.

You mention you checked all the currents with your multimeter. What was the current draw on the battery with the engine off, key off, and all accessories turned off (including the hood light -- might have to remove the bulb)? I would expect something around 100 mA. That would be reasonable (if not a bit high) for the current drain to the keep alive memory in the PCM and the radio and clock. That's nothing to worry about. If it's much higher than that, you have a drain somewhere. If it blows the fuse in your meter, you have a large drain somewhere (assuming it's fused at at least 10 A). If you have a sizeable current drain, one way to trace it is to remove fuses one at a time until the drain goes away, then start tracing circuits on that fuse.

-Rod

[Akrem]

Yes I am learning about this so bare with me if my messages are in different spots, I did check the battery with the car off, it was reading around 12 to 13 volts, but when we turned the car on it went down seems the distributer is not kicking in for some odd reason, but it works cause i had it checked at two different spots, and yes the black boxes are two different sizes, one bigger square one with all kinds of wires too it and a smaller one with just a few..I am thinking cause I traced one of the wires leading to under the dash is plugged in a relay thats not working to turn the Alternator regulator on to charge the battery could this be true.. Or maybe a falty, the battery is new and the alterator is new, well rebuilt but could two just be bad from the same place. I appreciate your response but for some reason the relay is not going back or something is not working besides the batt and alt...Sat I am going to pick a part and tearing out the dash boards of a Taurus to see what the wires going too..

[Akrem]

I am sorry I said Distributor I mean Alternator...

[TomV]

There is no relay to turn the alternator on or off. It is connected to the battery directly.

There are two connections to the alternator, one is the output to the battery for charging it (thick cable), the other is the input to the voltage regulator (also connected to the battery) to determine how much current should flow into the field coil (a pair of small wires to a 2 prong connector). This determines how much current comes out to charge the battery. The ground part of the circuit is routed through the alternator case.

With the car off, disconnect the plug to the voltage regulator of the alternator. Measure the voltage between the plug contacts. Since they should be connected to the battery anode (+) and cathode (-), you should read the battery voltage of about 12 volts DC. If not, you have a problem with the harness. Unless you have changed the harness recently you should have proper polarity since the car was working fine.

If itis OK connect it back to the alternator.

Measure the voltage between the alternator output (thick cable) and its case. You should read the battery voltage across these two points as well.

If this is OK then your cables are not opened up.

To check the quality of the connections you should have the car running. First,ensure the serpentine belt is sufficiently tight to keep the alternator spinning fast.
Next, probe the anode and cathode of the battery. You should have somewhere around 13.5 VDC. If not, then probe the output of the alternator by pulling back on the rubber boot over the thick cable and probing between the output bolt and the alternator case. If the alternator is not putting out any more than the battery measured voltage and is too low (should be at least 13.5 volts) then the alternator is probably bad. However, if the alternator voltage is fairly high compared to the battery voltage, then you have a poor connection between the alternator and battery.