charging problems: search function not helpful

[green94droptop]

Ok first off guys, I've already searched through the forum but I can't seem to find anyone with my particular situation.

This all started this morning on my way to work. The car just shuts off with no warning signs. I couldn't get the car to crank, so I figured the battery was dead. I had been noticing for the last couple of days that the car was becoming hard to start in the morning. I figured maybe the battery was going. Well, when I got it towed the to the repair shop, they hook up a test light and told me the alternator was bad. Now, this was suprising because it's a reman unit from Advanced Auto and less than 1.5 years old. But I figured it was still under warranty so no big deal. So he charges the battery up for me and I drive home on basically a charged battery. So I go swap the alt out for a new reman one and I figure everything is ok until I get it all put back together. On the test drive I noticed that the car all of a sudden just cut out for a split second then came back on (distributor/pip module? it's less than 2 months old). So I figure I better swap the battery out for a new one also, just in case. So the new battery is in and I'm driving it around. I notice the battery needle start to drop a tad at around 2k rpm. So I put a multi meter on the battery and it's only reading like 12.5 volts at idle with no change when I increase the rpm. I checked the post on the alt and it's the same thing; I know that the alt is getting power, just doesn't seem like it's charging the battery.

When the car is cold fine as far as the battery voltage. However, the car doesn't want to idle anymore; I have to keep my foot on the gas until it calms down. Also, when I drive it around, the revs seem to come down extra slow rather than how they used to come down.

Is there a fuseable link that I need to check? I know that the alt is getting power, just don't know if it's charging the battery. What about my reman'd distributor? How would I test the pip module to see if this one went bad?

Thanks guys.

 

[bjl95mustang]

Have you replaced the alternator plug on the wiring harness? it's the one that plugs into the alternator votage regulator. I think it costs about $10 from most auto parts stores. The bow will say new style ford plug.

 

[HISSIN50]

I like Brandon's idea. And there is/are a fusible link or two on the charge cable from the alternator to the distribution block. The links are a few inches from the distribution block connection. I would make sure that block connection is nice and clean and tight.

It well could be a cable issue. Resistance goes up with heat.

Good luck.

 

[BPA]

test lights are not good for deciding if an alternator is bad...well here is what i would do... check all of your grounds , remove any to the body or engine and clean them so there isnt any corrosion on them.these will weck havic on your charging system. then check battery voltage @ idle, then voltage @ alternator @idle. im not sure what the mustangs charge at but u should be seeing something like 13.5 v i would think. with a fresh battery fully charged there shouldnt be to much of a difrence from alt voltage and battery volts. if both are low like your 12.5v's you were seeing i would check alt. amperage. next.. @ idle u should be seeing something like 10 amps with the ac and accesorys off. and then test under load i.e. around 3k rpm. u should be seeing 100 amps or whatever your alt is rated for. if ur only seeing like 20 or so amps under load you have a bad alternator. its late and im sure im forgeting something but someone else will chim in. oh ya tools you will need.. fine grade sand paper or wire brush (cleaning your grounds) volt meter ie fluke or a sears digital meter and a clamp style amp meter. good luck with your repair Brian

 

[BPA]

the igniter wire unpluged from the alternator should have approx battery voltage as well. check out those things and rule out the alternator and then fault trace your problem further is it isnt fixed..

 

[green94droptop]

Ok when looking for the fuseable link, I find that there is one almost connected to the positive battery cable. When I unplug he connection, the car won't start. I guess that link links the starter? What about the alternator? If the link was dead for the alt, would the alt be getting any voltage?

 

[BPA]

see if u have voltage at the bk/o wire, that goes from the fusable links to the alternator. should be battery voltage.

 

[mo_dingo]

Yeah, the alternator should put out 14.4 at startup, and drop down to 13.6 after a few minutes. If you are seeing 12.6, that means you are running only on the batteries power (2.1V per cell = 12.6).

Back probe the alternator and see if you are getting anything. You should see at least 14V and the voltage regulator steps it down as necessary. Trace the alternator wiring. Check for continuity between each end of each wire.
Scott