1995 concord not charging battery

hi, i have a 1995 concord that is not charging its battery. the alternator nut reads 40vdc. i even tried a new alternator with the same results. it starts and runs fine so the ASD relay is most likely good. This leaves me the PCM..... how much are they? what a stupid place to put a regulator.... can it be anything else? i

Reply to
Joust
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Well, let's start from the start, here, before we go condemning the voltage regulator.

First, check for codes. There are diagnostic flash codes for the charging system.

To check the computer codes:

With the engine off, switch the ignition key on-off-on-off-on, leaving it "ON". Do not go to "start", just "on" during this procedure.

Watch the "Check Engine" or "Power Loss" light. It will turn on, then go off, then will begin to flash-out any trouble codes that have been stored. For instance, if it flashes:

flash flash flash

flash flash flash flash flash flash flash flash

flash flash flash flash flash flash flash flash flash flash

Then you have a 12 (one flash followed by two) a 35 (three and five) and a

55 (five and five). 55 means "end of codes" or, if by itself, "No codes stored. Check the codes and report what you find.

Are you quite sure you're seeing "40VDC" and not 40mVDC on your meter? If you truly had 40V at the alternator output, you'd be broasting batteries and popping bulbs and computer components all over the car.

What else could it be other than the SBEC (you said "PCM")? Could be a wiring fault, could be a faulty original alternator replaced by a typically garbageful "remanufactured" alternator.

And in the end, if you run through all the tests and find the voltage regulation function in the SBEC has failed, you have several options for a cost-reduced fix: You can get a used SBEC with a quick search on

formatting link
. Or, if you're reasonably electrically knowledgeable and have some basic electrical repair tools, you can install an external voltage regulator rather easily. On a '95 you must also install a resistor across the original field wires to fool the SBEC into not setting a charging system fault code and tripping the Check Engine light, but this is a minor additional effort.

Go do some diagnosis; if installing an external regulator becomes necessary, instructions will be forthcoming.

DS

Reply to
Daniel J. Stern

I had the same reaction to the 40VDC reading. Follow Daniel's advice, but I'd be interesteed to know what voltage you measure at the battery with the engine off (IOW, if it's not in the 12V range, then the meter is not reading what you think it is.

Do you maybe have a grounding problem?

Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")

Reply to
Bill Putney

HI,

Thanks for the detailed reply. I'm sure it will be very helpful and much appreciated.

So I double checked my voltage reading. It is indeed 40v DC but t is at the alternator lug. NOT the battery. This should be before the regulator and I expect it to be high. This would be consistent of a unregulated dc source with no load I'm sure. Could be wrong though, I'm not the expert.

I took it for a spin until the engine light came on.

Stopped and did your procedure.

The code that flashed is 124755

Any ideas?

Wiring looks good.

I put a second ground jumper on to be sure.

Thanks

Barry

Reply to
Joust

Code 47: Charging voltage low.

Measure the voltage -at- the battery with the engine running. Voltage drop the alternator output to battery wire.

Sounds like there's an open circuit between the alternator output and the battery.

Reply to
Neil Nelson

from the Shop manual:

12 - Battery Disconnect - Direct battery input to PCM was disconnected within the last 50 Key-on cycles.

47 - Charging System Voltage Too Low - Battery voltage sense input below target charging during engine operation. Also, no significant change detected in battery voltage during active test of generator output.

55 - End of codes

Looks like you are having an open circuit from the Alternator.

Reply to
Mr. Elbe

No, this leaves you with a broken connection between the alternator B+ terminal and the rest of the electrical system. The PCM is obviously telling the alternator "charge" or you wouldn't see 40 volts there. What is not happening is current flowing from the alternator to the battery.

Reply to
Steve

this alternator does NOT have an internal regulator. for some god awful reason of design ingenuity the designers decided to put the regulator circuit inside the Power train control module.

I'm off to trace the wires and connections to the PCM.

Reply to
Joust

Listen to what people who know are telling you: There is an open between alternator B+ and battery +!

DS

Reply to
Daniel J. Stern

WHY? That is NOT where the problem is!

You have sub-normal voltage at the battery. You have FORTY VOLTS at the alternator! You have a BROKEN WIRE between the alternator and the battery. The PCM is doing what God and its designers intended- telling the alternator to charge like mad because its sensing low voltage at the battery. And the alternator is complying, sending its output voltage WAY up there. But with a broken connection, current cannot get to where it needs to be.

Reply to
Steve

I realize that.

And it appears to be working... FWIW, inside the PCM is a much more forgiving environment than inside the alternator case.

Well, knock yourself out, but you should probably check to see if you also have 40 volts -at- the battery terminals, since you haven't mentioned an exploded battery, I can pretty much guarantee that there isn't.

IOWs, don't let the trees block your view of the forest.

Reply to
Neil Nelson

please excuse my ignorance guys. I'm into electronics but i cannot make a whole lot of sence out of automotive electrical drawings. there is too much information missing.

so a question. should the bolted lead comming from the alternator be a dierct short to the battery plus terminal? it is supposed to go to a fusible link (whatever that is) to the power distribution panel. then to the battery

Reply to
Joust

sorry Steve, I did not see your first reply. you sounds very much correct. I appologize for not paying attention to you in the first place.

now where would they hide that fisible l>

Reply to
Joust

That only happens on Japanese vehicles.

The term "short" implies that there is an unintended problem, (short to ground, short between feeds, etc.). The alternator output stud is almost always directly connected to the battery positive.

100% of the time, the correct test procedure would be to connect one of your VOM leads to the alternator output stud and the other to the battery positive terminal, start the engine, there should be NO MORE THAN .2 (two tenths) volts read on your VOM. Any reading higher than that indicates high resistance in the circuit that you've parralled with your VOM. Very simple, very basic.

A "fusible link" is a section of wire in series in the circuit that is usually a given wire gauge smaller (at least two, but can be more) than the circuit in question, this section of wire (fuse link) is covered in a Hypalon coating so that if it overheats and blows as a fuse would, there will be no flame or fire that can spread to the rest of the wiring harness (Hypalon doesn't burn). A fuse link is nothing more than a fuse that is not quite so easily replaced, and it's done that way for a very good reason (being, when they burn open, you have a serious problem that negates just plugging in another fuse).

Have you checked the underhood fuses?

Reply to
Neil Nelson

Perhaps because when its inside the PCM it usually lasts the entire life of the car? Failed regulators in the hot, dirty, vibrating environment of the alternator case are common, failures of the Chrysler PCM regulator are NOT common. In fact, more alternators are probably replaced because of failed internal regulators than because the alternators themselves have failed.

Reply to
Steve

Yes, the B+ terminal normally is a direct connection to the battery terminal through the wiring harness. I'm not actually sure if your car has a fusible link in that path, or if it has one of the oversized fuses (located in the under-hood fuse box as opposed to the in-cabin fuse box) in that path. Maybe Neil or someone who's fixed that problem before can point you the right way, but I'd pop the cover off the under-hood fuse/relay box and look there first.

You can also start tracing the wire back from the alternator toward the battery. Its a heavy-guage wire and should be relatively easy to follow in and out of various wire bundles.

Reply to
Steve

Agreed totally...

But you've attributed to me the words of another.

Reply to
Neil Nelson

OOps. I knew better, too. :-p

Reply to
Steve

I have to hand it to you guys. Daniel, Neil and Steve. you all had it pegged.

I found this morning with your help that the fusible link was indeed open. i jumpered it with a 30A fuse in series and the system worked perfectly for about 30 seconds, then it poped that 30A fuse. i took it to a Crysler dealership. I put on the work order that I suspected the fusable link was open. they worked on it (i saw three of their so-called experts working) for 3 hours at $85 dollars per hour. After that, they came to me with the news that they thought there was an partially open circuit between the alternator and the battery and it would take some time to find the problem............I lost confidence in the experts here. i explained that i knew that and that i told them and put that on the work order...they asked me if i would authorise them to continue working with the meter running at $85 per hour....ahhhhhh NO. easy answer. they put it on the charger so i could get home. after an hour i found out the hard way that they had run it out of gas while testing. Why they needed to run it that long i couldn't tell you. it had 1/4 tank when i brought it in. by this time the night shift had moved in. The experts were gone home. The night mechanic seemed to have a head on his shoulders. i had a chance to chat while waiting a bit. he was intrigued by the problem. he did a bit of poking and some huh-uh_ing he proclaimed that the computer was not doing things right. it was driving the alternator to full output all the time. He candidly recomended that i put on an external regulator and even recommended a place that would do it.

Daniel, you told me that "if installing an external regulator becomes necessary, instructions will be forthcoming" Is this offer still valid? Is there an off eth shelf regulator that i can get or do we resort to home brew. I can do the home brew type.

You guys have been very helpfull. I appologize for my ineptitude and your forbearance in this matter. I am getting it but am a bit thick. sincerely Barry

"Joust" wrote in message news:KNogb.2162$G snipped-for-privacy@news20.bellglobal.com...

Reply to
Joust

Surely.

NAPA Echlin VR38, it'll be in stock. Also get an Echlin VRC38 connector plug -- usually special order, so call tomorrow AM.

1) Remove your existing field wire assembly from the alternator. This will require some cleverness, as it's part of a moulded assembly that includes the two side-by-side flag terminals that are the field terminals, and the larger ring terminal that is the output terminal. The output terminal must stay, but the flag terminals must be removed from the two studs on the back of the alternator. Do not damage the flag terminals! 2) Using an ohmmeter, measure the resistance across the two studs on the back of the alternator. Write down the result. You will need to obtain a resistor of approximately this value and place it between the two flag terminals to fool the computer into thinking it's still in control of the alternator. Use a resistor robust enough to withstand 4A current. Insulate (wrap, etc.) the flag terminals and resistor assembly so that they do not short to anything else. Do this carefully -- neatness and thoroughness count. 3) Your VR38 needs to be mounted to a sturdy surface that won't get too hot. Try for a firewall or fender location. It also must have a good base ground, so if you are unsure, run a wire from one of the regulator mounting screws to the alternator's housing ground terminal. 4) Your VR38 has two electrical terminals, and your VRC38 connector has two wires.

The terminal/wire that's at the "top of the triangle" needs to go in TWO directions: To a source of ignition switched +12V, and to one (either) of the field studs on the back of the alternator. Wire carefully and neatly and make sure you don't overtax any existing circuits.

The terminal/wire that's on the right side of the triangle goes to the other field stud on the back of the alternator. Wire carefully and neatly.

And...that's it!

DS

Reply to
Daniel J. Stern

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