Alternator Light
 

My alternator light is staying on from idle to about 2500 RPM intermittently. Time to replace or anything to check first? It’s an SC engine.

I’m somewhat handy, is this difficult to do?

Well, it is not the alternator light that is at fault; it is reporting a problem with the charging system. The alternator and/or regulator may be faulty. Other possibilities include wiring and battery.

Yes I meant replace the alternator. Is there a test to see if it’s the alternator or regulator or are they one unit?

Yes.

It can be either on a car that is 40+ years old.

Please state the year of the car, and is the engine original, or a swap. More details on the vehicle will help in an accurate diagnosis.

Can be a loose belt

^^^^^this ^^^^^^

Miss Cleo may know, but the rest of us likely don't.. :)

I recently removed my alternator as the bearings crapped out. You do not want to remove the alternator unless you must - it is a royal PITB. Your SC has either an external VR or an internal VR, depending year and if alternator was replaced/up-graded. Behind the black cover left rear fender is where the external VR would be, if you have one and the wires are connected. If not, or if the VR is there, but the wires are not connected, then your alternator has an internal VR.

As Mahler9th stated, it could be a loose belt, so start with that. If good, then check the VR if external.

Jason

My car is a 1977 Euro 911. It has a 10 year old rebuilt 3.0 SC in it.

What year SC engine?
Do you have an internal or external voltage regulator?
(look beside the CDI for an external one)

What kind of voltage are you getting at the battery? OFF, idle and revved.

Internal VR

Loose belt, regulator or worn brushes are the most common culprits. If it is only on at startup until your first higher rev, that is normal. With worn brushes the light ends to flicker a lot. With a loose belt, the light tends to glow dull under electrical load.

Alternator light came on and stayed on my '76, replaced regulator before taking alt off, fixed it.

So my light on is intermittent, goes off above 2500 RPM, anyone vote to replace the brushes or is that a PITA to do as well? Replacing the alternator is about $800.

To get to the brushes, the unit has to come out. Tedious work but I'm no mechanic and I managed it - if you do remove it, make sure to take multiple pics of the removal, including orientation of wiring as well as how/where the air deflector is attached to the back of the alternator. Make some marks on both so you can line it up properly on re-install.

An alternative to buying a new one would be to have yours re-built. Get a recommendation for a local shop that does that work, you could save a lot of $.

Jason

since the VR is triggered by the alt lamp, is the correct lamp in the gauge?

Get one of those cigarette lighter volt meters. I got one off of eBay. It helped to know the voltage with my charging problem.