Red Light On

I came out to my '74.5 GT a few weeks back and found the battery was dead as a doornail. It had sat for about a week so figured there was a draw of some sort. No problem, I charged the battery and re-installed only to find the red charging light on the dash glowing even with the key is off and/or out. It only goes out if I turn the key on. All else is normal except the CD player no longer works in any capacity and the system is not charging itself (discovered on a long drive the other day). I searched for a similar post but didn't find one.

Any ideas? Auto electrics are my weakest subject.

Thanks in advance.

Scott

As a general statement, 90% of symptoms involving the red lamp are related to a failure of the diode pack. In your specific case, I would rate the likelihood even higher than that. There are a couple of other red lamp problems that can involve worn brushes and bad regulators, but neither of these fit your symptoms.

The diode pack has to be replaced. The good news is that it is fairly inexpensive. The bad news is that you will need to solder - make sure you use electrical and not plumbing solder.

While you are working on the alternator, you might as well replace the brushes.

The procedure for replacing the pack is fairly obvious. Pull the alternator off the car. Pull the end cover (plastic part) off. From memory there is a nut and maybe a couple of screws that have to come out. Then unsolder the old one and solder in a new one.

Sounds pretty straightforward Terry, thanks.

And I have soldering iron! Who knew that's come in handy one day?

Terry is spot on with the diagnosis and the fix.

Go to Radio Shack and bu a clip on heat sink. Clip it to the diode pig tails to pull off some of the heat from your soldering.

Use a sharp iron that heats quickly.

If you haven't soldered much before practice and get a feel for how quickly things come apart and how much heat you need to apply to stick them back together again.

Jack

[quote=ingoldsb]
There are a couple of other red lamp problems that can involve worn brushes and bad regulators,

The bad news is that you will need to solder - make sure you use electrical and not plumbing solder.



quote]

A list of red lamp problems would be great for a separate post article.

What is the difference between plumbing and electrical solder.?

Years ago, some of my solder joints used to go acidy/corrosive blue,

Did not take much notice as to why then, just cut and redid them.

I have been on the same large solder roll for a decade now, so I have forgotten what it should be.

http://technologyinterface.nmsu.edu/fall97/electronics/solder.html

http://www.doityourself.com/stry/h2weld

Solder differences - mainly 2, plumbing solder flux is typically corrosive and electrical solder flux is not; because of the elimination of lead from plumbing solder alloys, its melting termpearature is higher than electical solder.

Bone amateur here, indeed. I haven't soldered since 7th grade? I do have a kit though. I'll give it a try, I have nothing to lose and maybe some charging to gain.

Where to get the diode packs I wonder? Moss doesn't list them.

Thanks for everyone's suggestions, I'll post my progress when I get it apart.

Hi all, I hope everyone's had a good holiday. I certainly did. With that, on this final day of vacation, I dug into the GT to figure out what's up with the alternator. Things pointed to the diode pack (rectifier) judging by the symptoms. When I pulled the alternator off, I heard a rattling of some piece inside. Here's a pic of that piece...

The arrow points to what I think isn't right.

Then again, this piece doesn't look right either? It soldered but doesn't attach to any wire or anything. I'm laying my technical expertise on pretty thick, I know...

I'll pull the rectifier and replace it. Let's hope I order the correct one.