I can't seem to keep this car running for more than a month at a time!

For the past few days my dash lights have been glowing dimly some of the time.

Not all of the dash lights but lights that shouldn't be on.

I suspected something was up with the alternator or battery.

Then today the car dies going down the road.

I put a new battery in and drive home.

Check the voltage at the battery with the car running and I only get 12 volts.

Swap in a known good alternator and... still 12 volts.

But now the dash lights are bright as can be (the ones that shouldn't even be on).

New alternator = bright dash lights but still no charging?

I read that I need to get into the instrument cluster and fix something with the wire going from the idiot light to the alternator but I'm not sure I get it.

Can anyone explain it to me?

Thanks!

Well I decided to get a new alternator having temporarily forgot that I was planning on doing a laundry list of such items as preventative maintenance (so I can go on a nice road trip this summer).

I disconnected the ground wire, cleaned it up, gave it a few good tugs and reinstalled.

I also removed the instrument cluster and checked all the connections. One minor issue is that there is a wire behind the instrument cluster that does not seem to have a place to go. I don't know if it was already disconnected or if I pulled it off while removing the IC. It is a spade connection (I got the other spade connection in place) and the wire is red/white. There are two spades on the back of the IC that have a rubber band of sorts around them which made it impossible to install the wire on them. Any ideas where it goes?

I cleaned up D+ real good, reinstalled everything and viola! 14volts.

Now it's time for some new belts and a water pump.

Thanks for all of the help everyone!

So did you replace the alternator or did cleaning up all the wiring fix it?
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Post Back. That's whats makes this forum work.

I replaced the alternator and cleaned up the wiring.

My guess is that it was the alternator since the wiring looked good.

Red/white is for a tachometer, do not connect it to anything but a tach or you will let the smoke out!
Dan

Thanks Dan!

Wish I had a tach.

I don't know what year this is but the small red wire can be replaced at the large grey connector on the firewall and run to the alternator on the passenger side of the engine bay. This may fix the problem.
Dan

Thanks for the tip Dan. I'm hoping I don't have to tear into the instrument cluster.

If you have the large grey connector on the firewall in the engine compartment you don't need to go to the cluster. What year is the car?
Dan

Dear LM240V

Is this the same Volvo...

when I suggested the 357mag revolver?

For More Fun and Satisfaction.

choose from these Rifleman Classics and then send the pictures/video. :) Prob will be worth more than the car with proper marketing on YouTube KillMY240.com

Considering, I'd go for the BigBoy. You'll feel great about it ...

http://www.henryrepeating.com/henry-rifles.cfm

I might as well, I can't take the damn thing on a vacation now or I'll be a nervous wreck the whole time.

Probably would need to take along $500 in spare parts and a full toolbox just to feel comfortable.

Ah well, I'll never learn. This fix, yeah, this'll be the one!

I might as well, I can't take the damn thing on a vacation now or I'll be a nervous wreck the whole time.

Probably would need to take along $500 in spare parts and a full toolbox just to feel comfortable
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

for that much 500 you can rent a New Volvo(if you have loyalty to the brand) or whatever for the vacation and then come back and re-think the one you have.

RENT

I found a break in the wire from alt to light, but the sheath of the wire is still intact.
Found it by probing from alt connection back down the wire an inch at a time. Found the break about 3-4 inches from the alt connection!
You will need a meter with sharp probe to penetrate the sheath.
I reworked it all the way back to the light on the speedo.

I'll start at the alternator end, seems good and beat up.

The wire literally had a break in it?

I was thinking I had a short, are all those lights an indication of the thin red wire not being connected to the alternator?

I'll try disconnecting the thin red wire from the alternator and see how it effects the dash lights.

"I'll try disconnecting the thin red wire from the alternator and see how it effects the dash lights. "

You're on the right path here. With that wire disconnected, the lamp test function (key on motor off) should yield no battery light. Start the motor, and with that wire still open (disconnected) that light should remain off. The light should come on when you ground the end of that wire. Make sure you have a ground on your alternator -- that was the thick blue wire that connected the case of it to the motor mount bolt.
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Art Benstein near Baltimore

The 50C5 was introduced in 1948, to address concerns that the set might pose more of a shock hazard to the user if the 35W4 and 50B5 were to be accidentally interchanged. The 50C5 is a 50B5 with a different pin-out.

Art, The battery light is on with the wire grounded and KOEO.

The battery light is on with the wire grounded and engine running.

The batt light is off with the wire open and engine running.

It seems to have failed the KOEO test but passed the rest.

Does that indicate anything?

I also noticed that with that skinny red wire connected to the alternator, it has continuity to ground.

Is that a short?

That KOEO stood for Key On / Engine Off, sorry for the confusion.

"That KOEO stood for Key On / Engine Off, sorry for the confusion. "

LOL - or Laughing Out Loud. Yeah someone pointed out O could be for On or Off, huh? We get too wrapped up in trying to use "the jargon."

Part of that jargon is the term continuity. Determining something unknown that exists between our meter probes is indeed a substantial hunk of copper wire can be a little more involved these days, than hearing a beep from the DMM.

Not sure I have the whole picture yet, but it is clear to me your D+ wire from the alternator to the instrument panel is OK. The less-than-battery voltages you read on it with nothing turning sound right to me.

Two assertions you made are crippling the troubleshooting process. One, your alternator is "known good." Two, it is grounded. Nah, the DMM isn't your tool for knowing this, unless you use it in voltage mode in operation.

One I make is just as dangerous: you've connected the wires correctly. There is a spade on these alternators marked "W" which has received the D+ wire on other brickboarder's cars, and more than once.

A second given, is the coupling between the engine and the alternator is tight. I know of a guy who was about to tear out his hair on a problem with your symptoms only to find the belts were silently slipping just below the speed at which the alternator begins to develop power output. These things don't get much press because very few of us have the stones to come back and admit what simple things have succeeded in confounding us.

I am going to post a diagram of the charging system which takes all factors into account. I know many of us have seen me post this many times before, and for some reason no one comes back and says "thank you, Art, that drawing explained everything." Well there's a first time for everything, and this certainly isn't Rocket Surgery.


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Art Benstein near Baltimore

I had no Monet to buy Degas to make the Van Gogh.

Art, thanks for the wiring diagram but I'll have to admit, it might as well be in Chinese because I just can't read these things. Nothing to do with your diagram, it's on my end. My grandfather ran the electrical works for a country. My theory is that he used up all the knowledge available to my DNA regarding electricity and now I'm left brain dead on the subject.

My alternator came off of a running vehicle and was functioning at the time. Is it a known good? I suppose it is questionable but I could argue that there is no possible way on earth to be 100% sure it is a known good, even a brand new one. I verified that the brushes are well over 5mm in length.

Ground was checked with the meter, visually, and with a good tug, how many ohms should I be seeing for an acceptable ground?

I don’t recall there being another spade on the back of the alternator but considering that this issue arose without me moving any wires around I think it’s safe to say it is connected to the correct spade.

I checked the belt tension and verified that the alternator is in fact turning, I’ll have someone kick the RPM’s up while I check for a charge.

I have found that D+ has continuity to ground between the gray connector on the firewall and the instrument panel, that sounds like a short to me, correct?

Art, thanks for the wiring diagram but I'll have to admit, it might as well be in Chinese because I just can't read these things. Nothing to do with your diagram, it's on my end. My grandfather ran the electrical works for a country. My theory is that he used up all the knowledge available to my DNA regarding electricity and now I'm left brain dead on the subject.

Cute story, but I don't agree. Left brain or right brain, you will need to acquire some basic understanding of electricity to permit DIY maintenance of cars in the computer age. Part swapping will only get you so far, as you have found out.

My alternator came off of a running vehicle and was functioning at the time. Is it a known good? I suppose it is questionable but I could argue that there is no possible way on earth to be 100% sure it is a known good, even a brand new one. I verified that the brushes are well over 5mm in length.

Put it back on said running vehicle and retest. You had the regulator out to check brush length; are you that certain it is back in place and making good connection?

Ground was checked with the meter, visually, and with a good tug, how many ohms should I be seeing for an acceptable ground?

"Ohms seen" are irrelevant to acceptable ground in a high current circuit. Your ohmmeter cannot come close to qualifying that ground. NASA's ohmmeters wouldn't either. The good tug and your eyes is what you will use. Then, when running, a voltage reading referenced to the battery negative post, to verify.

I don’t recall there being another spade on the back of the alternator but considering that this issue arose without me moving any wires around I think it’s safe to say it is connected to the correct spade.

I'm lost here too, but that certainly is the air gap between us. You can swap alternators without rewiring? Or are you now saying the alternator worked for a while and suddenly quit, yet this is a "known good" unit. I'd like to help, but I'm missing some important fact.

I checked the belt tension and verified that the alternator is in fact turning, I’ll have someone kick the RPM’s up while I check for a charge.

The RPM of the engine is not the question. It is the RPM of the alternator rotor that is important to generating electricity. The problem won't be checked by getting someone to goose the accelerator, which you could do unassisted by reaching for the throttle spool. Proving this disconnect, which can occur at the belts or with a slipping harmonic balancer is not easy -- that's why it is on the last of the suspect list, and tends to fool some reasonably experienced folk.

I have found that D+ has continuity to ground between the gray connector on the firewall and the instrument panel, that sounds like a short to me, correct?

What is continuity?

A very simple way to substitute for the "pre-excitation" circuit -- that D+ wire through the instrument panel -- is to remove the small red wire from the alternator and connect a dash light bulb (any small 12V bulb) between B+ and D+ terminals on the alternator. Make a test light from such a bulb with clips on it. After you've fixed your alternator, you'll find this the handiest electrical tool you own, and it won't lie to you like your DMM does. Add a few other items you can make from junkyard parts, and keep it in your glove box.


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Art Benstein near Baltimore

Fruit flies like a banana. Period.

Excellent, thanks for the clarification Art!

I know the blue ground is attached to the alternator, not sure about the other end.

Sometimes the vibration of the alternator fractures the metal inside the terminal's insulation, just like that open wire described by j----- so be sure to give a good tug on both ends to know that ground wire is intact.
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Art Benstein near Baltimore

Bakers trade bread recipes on a knead to know basis.

I checked it with a DVM and it is grounded, connection at the alternator is good.

From a guy who has been bit by this twice...just because you show continuity now, does not mean it is always providing ground. In my case, the wire had corroded/fractured inside the ring terminal on chassis side. At idle, charged like a champ. Accelerating, decelerating or cruising above 2500 rpm gave an intermittent connection as it vibrated the broken wire end in and out of the ring terminal.

On my '76 I tried everything and even carried a spare fully charged battery around for about three months. Found the bad wire by accident while changing a motor mount.

On my wife's '81, I knew what it was when the brush/regulator combo did not fix an intermittent charging issue.

The only reliable way to tell is to remove the wire at both ends, take it out of the car and do a thorough yank and twist test on both ring terminals.

Thanks Udo, I gave it a good yank in the car but I might as well pull it out and get a closer look.