Hi everyone!

After my cam seal change and degreasing the engine, I've got a intermittent charging problem. Sometimes it's charging at a full 14.3vdc, other times nothing, with the dim warning lights. When not charging, the voltage on the alternator exciter wire is 6.3vdc while the engine is running, and 9.4vdc when the engine is off.

The brush pack/regulator have plenty of brush length, only 20k miles. There was some oily residue on them from the cam seal, but I cleaned them, and what I could inside the alternator. The exciter and other connections looks clean.

Possibly there's still some oil inside the alternator causing the problem? Why would the exciter voltage be so low?

Any ideas?

Thanks!

"Any ideas? "

Belt oily or harmonic balancer slipping. Ground broken.
--
Art Benstein near Baltimore

"A harmonica plays better too, once you learn to keep the slobber out!" -machine man

An Update:

I connected a jumper from B+ to D+ on the alternator and have full charging. It seems my "S" Diode Box (Japan) may be the problem, not providing B+ to the exciter.

Does anyone know what or where this is located? Thanks

https://postimg.cc/NKd68C3t

I saw your thread on TB, and I respect John's experience, but pre-excitation with the jumper to B+ is expected, and not proof there's something wrong with the supply from the instrument panel.

You said the symptoms were intermittent, I believe, so I expect things could change just by your actions or its movement. Be sure the belts aren't silently slipping - a common way to mislead you; the result of that will be dim warning lights as the electrical load results in mechanical load.

A test is, like John suggested, ground the D+ wire terminal. Don't trust the alternator case for that ground. Do all four lamps glow brightly at key on? Bat, parking brake, brake failure, and bulb failure? Then plug the D+ wire on the alternator's D+ terminal, measuring voltage in circuit, key on, engine stalled. Should be near 1.5 V. Lamp test should be be working full brightness. If not, chase that ground wire.

The "diode box" is a Japan-market only use of D+ for the exhaust gas temperature warning unit you don't have unless you've got a car from Japan. Unless you were working on the cluster, I think you're suspecting it to be like John's trouble is a red herring.

--
Art Benstein near Baltimore

The reason a dog has so many friends is that he wags his tail instead of his tongue.
-Anonymous

Thanks for the good info Art. I pulled the cluster and removed the circuit board, and found nothing of problem. I have had some solder joint problems and thought there could be something going on in the cluster. I'll put it back together and go through your thoughts and test.

Since I plan on installing a volt gauge, would there be anything wrong with bypassing the battery light setup, and just wiring d+ to the ignition switch?

Thanks so much.

"...would there be anything wrong with bypassing the battery light setup, and just wiring d+ to the ignition switch?"

On turbobricks, not a thing wrong. Modification is the mantra there, where most all believe the engineers knew nothing about what they were doing when the car was designed.

You could supply the pre-excitation voltage from the ignition switched battery and perhaps be more comfortable it would be there when you needed it. The cost would be the idiot light of course, and the lamp test for the other three warning lights in the '92. Voltage gauge would be great -- I have them too -- but you might not be checking it when the alternator decides to go; it doesn't flash at you like the idiot light.

I think you could fix the problem, make it work like it is supposed to work, and add a voltage gauge. The 2" analog gauge is good looking, but even a cheap digital battery meter plugged into the cigar lighter socket will provide the information.

https://www.brickboard.com/RWD/volvo/1438600/220/240/260/280/installed_voltmeter.html
--
Art Benstein near Baltimore

There is no psychiatrist in the world like a puppy licking your face.
-Ben Williams

Art,

I understand. I usually do maintenance and needed repairs and have gotten 460k+ miles so far (The goal is one million). It had 100k when I bought it 21 years ago. After everything I read about the idiot light and the potential problem it could pose if it burned out unknowingly, I thought a nice 2" Volvo volt gauge would be nice above the 2" Volvo oil pressure gauge, and give me a realtime idea of what's going on.

If I do go this route, where would I easily find power from the ignition switch? Is there a connection from it to the instrument cluster? Thanks so much!

"After everything I read about the idiot light and the potential problem it could pose if it burned out unknowingly..."

That's what lamp test (key on engine stalled) is for.

"...where would I easily find power from the ignition switch?"

The blue wire to the speedometer L plug. Remember, it isn't protected by a fuse until it is internal to the panel.
--
Art Benstein near Baltimore

A dog teaches a boy fidelity, perseverance, and to turn around three times before lying down.
-Robert Benchley

Thanks Art!

I'm trying to understand something about this.

When I jumper B+ to D+ (exciter) on the back of the alternator, it charges like it should. When the exciter wire from the instrument cluster is connected, the voltage is too low to activate a charge. It seems then the problem is in the cluster? And I can't seem to find a problem there.

I do have full B+ on the exciter wire sometimes when disconnected, but that drops when connected to D+. It seems the problem with a bad trace or connection, not passing enough current when loaded.

Thoughts and ideas? Thanks so much!

A test is, like John suggested, ground the D+ wire terminal. Don't trust the alternator case for that ground. Do all four lamps glow brightly at key on? Bat, parking brake, brake failure, and bulb failure? Then plug the D+ wire on the alternator's D+ terminal, measuring voltage in circuit, key on, engine stalled. Should be near 1.5 V. Lamp test should be be working full brightness. If not, chase that ground wire.
--
Art Benstein near Baltimore

I wonder if other dogs think poodles are members of a weird religious cult.
-Rita Rudner

Hi Art, Blindboy, Phil,

I have the problem fixed now, but I'm not exactly sure how I fixed it. I put the cluster back together, cleaning all internal contacts and connector posts (even though they looked shiny and clean). I started the car and everything is fine, charging a solid 14.25v at idle speed of 500rpm while getting the battery back to full charge. I turned the headlights, ac, blower on full, radio, etc, and voltage stayed a constant 13.84vdc. Road test and lots of driving, everything is good. Before, it was all over the place, charge, not charge. All good now! Once again the 240 heroes come to the rescue!!! Thanks to all of you who helped me keep my wagon going.

Hi,

Glad to hear that you solved the problem.
I was watching your thread and WoodShavings about alternators not charging correctly.
They seem to be the same issue of a higher then normal resistance some place. Jeff of WoodShavings was wrestling with the idea of a new rebuilt alternator could be defective.


It seems to be a consensus among us all that there wasn’t enough D+ current coming from the instrument cluster.
Whether it was on the positive or negative side of the circuit, there was a resistance, stopping the proper amount of current flow.

Jeff wrote that he was about to put wire on or a take wire off when he should not.
I advised against it right off! It’s a big warning from manufacturers.
I think he is waiting for more time or better weather for now as he has been quiet.

I was going to write up something about using the low millivolt setting on hand held voltmeters to trace out energized circuits.
It was brought up from from the specifications given by B.B. in the other thread.
Art brought in his expertise along the same lines but putting leads on and reading the results needs background knowledge to grasp why.

I was going to layout how it is suppose to work logically to get those readings but working from the voltage supply direction rather than with the end result being just X amount and deciding I got to go fish!
It can help “give assistance to find resistance” with careful observation and lots of perseverance.
I see it’s too late in your case.
I think you found it out or got rid of it with lots of TLC. 🧌

The instrument cluster should not be ruled out to be immune to corrosion issues.
It lies in between the wet foot area and the windshield.
The inside of the dash is not as prone to stay as wet because the firewall or engine is not that far away.
The coldest places get the most.

The drivers foot well catches moisture all the time.
Moisture rises up while evaporating. Warm legs and feet help that along
It in turn affects the fuse panel as the hinge side of the door gets cold.
The windshield gets is wind chilled.
Energy tries to stop moving. It travels towards or is attracted to cold anything to reach a less agitated state of equilibrium.
The Results we see all the time are foggy windshields and seldom noticed within damp connections, where ever they have to be.

I’m hoping that WoodShavings sees your solution.
There are not that many components in a charging systems be this elusive.

Phil

As Art suspected it could, and it has, my charging problem is back! Makes sense since I never found the cause, it had just started working normally.

Currently, with key on and engine not started, The cluster idiot lamps all glow normal brightness. When engine starts, the battery, parking, brake failure, and bulb failure all glow dimly and voltage from the alternator is below normal battery voltage.

If I connect from D+ wire through 12v test bulb to D+ terminal on alternator, the bulb doesn't glow. When I test current through this same test circuit, it's pulling only 120mA.

If I connect the 12v bulb from B+ to D+, the bulb glows until I start the engine, then the alternator charges normally. If I disconnect the D+ wire after a few seconds, the alternator continues to charge normally.

I have removed every ground connection in the engine bay, cleaned and tightened. They actually all looked shiny and clean already. (This car has never seen snow).

I assume my problem is still in the cluster. I traced everything and checked all points for resistance last time. Ideas as how to proceed?

Thanks so much!

Hi,

I as far as the D+ power, that is fed through a light bulb. It creates current limiting resistance and therefore voltage drop with the engine on or off.
A variation of brightness is a symptom of low output like a slippery belt or for those other reasons you are eliminating in the post.
When the alternator starts giving an output, the output pushes against that current flow into the light bulb. It glows dimmer to completely out.
From that point the alternator becomes self-feeding to the rotor by the regulator that’s monitoring the battery’s B+ voltage or the entire system demands.

I think “Blindboy” has the right idea about the grounds as they are half of all charging circuits.
I mean in Circuits being both positive or negative.
Starting at the battery the engine block and a body ground cables will include the cabins instrument cluster circuit.
The big wire positive has one interruption point on the starter motor terminal that can become loose.
There is a feeder wire to the cabin on the positive cable too.
Someone on here said that cleaning them made all the cars components more “perky.”
Now that’s an emotional observance that I have heard with electricity.
Except when you get shocked by a plug wire!
😵‍💫😳😬🤔


Since we know you just replaced the cam seal and that comes with associated things like getting belts off.
I would make sure that the alternator’s housing has its own ground wire, to the engine block, in pristine condition. It has to be grounded because of rubber bushings.
If it’s anything close to an original wire bending the alternator way back a few times will take a toll on the terminal ends. Strands break internally.

For the life of me, I haven’t understood Volvo’s obsession with rubber mounting the accessories.
Especially on an item, the combustion engine, that’s already louder than the accessories themselves.
The alternator and the power steering pump are centrifugal in nature as they don’t exactly knock or vibrate?
You have to put a stethoscope on each to listen to the bearings below the sounds of any “tired” V belts.

As far as the cleaning goes I wouldn’t think any residual solvents hurt things. Some evaporate oil up and away.
But if the alternator’s regulator brushes were freshly changed without inspecting the rotors slip rings for deep grooves, they could now be presenting a reseating problem.
If they are loosing contact or possibly arcing a little the lights will flicker some.
It’s the same as worn out brushes.

How many miles are on the alternator’s slip rings?

Phil

i believe there are multiply grounds bt the doors? maybe by headlight?? clean them all