Photodan

Started the car this morning and the alternator light came on with the needle sitting at the bottom of the gauge, gave it some revs and it picked right up and the light went out. Car drove fine all day, charging normal. Started the car later in the day and the needle was sitting down the bottom of the gauge again but no alternator light. Now when I turn the key I get no alternator light and the needle is barely off the bottom.

I'm not sure why I'd get no alternator light when I turn the ignition? Is the alternator shot or is it something else? I did notice with the new battery I was getting varying levels of charge, always over 12v but sometimes nearer 14v.

Forgive me but electrical stuff just makes my brain hurt

Ideas anyone?

phil823

on my car the alternator light is on and stay on when i start the car untill i rev the car to about 1300 or so. then it kicks off and says off..........Until i start turning on heater, and high beams and such, then the light slowly comes back on but not to full brightness.

ive actually found that when i start my car, such as in thye winter and i dont rev it up, the car will somehow after an un known amount of time will shut itself done.....its wierd

mabey its cause my battery is like 3 years past the replace date on the battery itself.....but if it works, why replace it!
I also have an 1984

John_AZ

PhotoDan,
I would start by cleaning all grounds. The new battery should have clean terminals. Did you clean the bellhousing NEG ground? Put a piece of tape over the TDC belhousing hole.

Clean the starter cable connections. The alternator charges the battery via the starter.

The alternator has a tiny wire that goes to the idiot light. Check the condition of the wire for cracks that could cause a short.

phil823,

3 years past replace date? You should replace this battery. Compare it to a rechargeable 12V drill in your shop. After a couple of years the charge will only last a shorter and shorter time.
Your car battery is the same and why take a chance on burning out the DME computer with a low battery?

There are too many parts that can be damaged by contact arching and a low charged battery sending too many amps.

GL
John_AZ

Photodan

Update: This morning the car still cranks fine but the alternator light is very dim and the needle is sitting around 11v.

Thanks John. The battery is a few months old. I'll go through all the grounds and see if that helps. Otherwise I'll just pull it and get it tested. I really don't want a new alternator for Christmas.

peanut

Intermittant charging ....commutator brushes probably. very easy DIY to replace .

if you replace the alternator a Ford Scorpio is essentually the same at half the price

John_AZ

Thanks for the reply.

The VR brushes should be 1/4 to 5/16 inch long. If you pull the alternator, check the brushes. A VR is cheap and easy DIY. If you replace the VR, you need to "dress" or sand the the slip ring on the alternator shaft where the VR carbon brushes sit to remove peaks. Emery paper and spin the pully should work if you can get the emery paper in the grooves.

The VR did not solve my dim dash light issue after replacing. I bought a rebuilt and solved the problem. I went from a 90 amp OEM to a 115 amp to overcome old wires and aging fuel pump current draw.

GL
John_AZ

Eric_Oz_S2

Hi Dan,

Hope you finally got your TT sorted.

Suggest you pull out the regulator out of the back of the alternator and check it out. Replacement parts are cheap from Paragon - probably worth just replacing it anyway and see if that makes a difference.

Goof luck

misnblu

Any reason why I've got to rev the engine just to get the alternator started on crank up?
This seems stupid compared to any other car that I've owned and have never seen an alternator do this.
Most alternators are automatic once they start to spin but no my 944, you've literally got to rev it on start up to get it spinning or so it seems.
Btw, I've just gotten this car so don't know if this is normal for the 944 or an alternator on the verge of going out.
Some insight on this would be nice too and hope it's still on topic here in this thread.
Thanks in advance.

John_AZ

The rpm (idle) of the engine should be at about 900-950 to get the alternator to spin at about 1200rpm which should turn off the dash light. If the dash light stays dim/flickers, the alternator is not charging your battery.

Check the tension of the belts and the VR brushes. Clean all cable ends especially the starter cables.
How old is your battery?

My guess is that a diode or 2 is going bad and the alternator should be replaced.

If the alternator tests OK out of car, and your battery is good, you could run a thick cable direct to the battery from the alternator and bypass the starter. Some add a negative ground from the alt to the block.

Normal? Not on my cars.

GL
John_AZ

misnblu

Thanks and I plan on doing some work on the car as I've only had it 3 weeks now.
But I do plan on upgrading the wiring on the hot and ground side along with checking the belts etc.
The battery I've got to replace with a sealed unit so I won't have to worry about the acid affecting the battery tray which has to be cleaned up and redone.

I just thought it to be weird on how you had to rev the engine to get the alternator to engage if you will to get it going.
Thanks again for the response.

peanut

I think its pretty obvious that it is the brushes that need replacing. You are either going to have to remove the alternator and strip it and check or get a garage to test it. Otherwise its all speculation

sweetskillsrk

+1 Eric_Oz_S2
Definitely check your voltage regulator, easy to check and replace if needed. My buddy's BMW 528e alternator died and so I pulled it and ordered another alternator. In the end wrong alternator so I went to someone else and ordered another alternator, that one was also wrong. Come to find out I could have just ordered a new voltage regulator and saved myself so much aggravation, didn't even have to take out the alternator, oh well. I hate electrical problems, so freakin confusing. But anyway, definitely check it and good luck.

V2Rocket

did you use a late 944 alternator?

misnblu

Thanks guys and that's something I'll check too.
It won't hurt to do this and not have to worry about it down the road.

John_AZ

No, rebuilder used AL29X and upgraded the internals.

John_AZ