When my car idles, which is below 1K... probally around 800ish the dash lights start to blink rapidly.

The car is a 1985 GS, and the idle has been set this low smoothly for over two years so that's not the problem.

The stock voltage gauge on the dash dips deep below 12, prob just below 10ish.

I have some ideas where to start, but being I have a trip I have to make tommorow afternoon, I'd rather fix my car vs borrowing someone elses and could use any further input this way I'm not guessing / trouble shooting last minute.

I'm hoping it's something stupid and is a easy fix. Thanks.

 

Sounds like maybe the voltage regulator in the alt is going out. I would take the alt to an autoparts store and have it tested.

 

agreed, Alternater is the best bet, and easyest.

 

sound like alternator to me. i have a similar problem.

 

The only thing that tells me *it might not be* the alternator is when the rpms are over 1000 the voltage kicks up to 14ish and the blinking stops....??

 

you need a good ground

 

Same thing happened on my 85 GSL-SE recently. Swapped alternators, problem gone. Did just like yours did too as far as voltage output at idle. Stepped on gas, voltage went up, lights on dash went out.

I would look hard at the alternator like others have suggested.

 

I went with cleaning the grounds first being the problem started on a rainy day... I cleaned all the grounds and fuseabile link connections real good. It looked in need of being done anyways but it didn't fix the problem.

Swapped out alternators, problem gone. THANKS.

Edit: Could the alternator be opened up and cleaned to fix the problem..?? Being it started on a rainy day w/the moisture and all, something prob is just making bad contact same scenerio as if the ground went shity.

 

Depends on the problem. If you think it got wet, just bring it inside and let it dry out. I think it is probably a problem in the voltage regulator, though. Last time I had an S5 alt rebuilt (bad regulator), it was about $75 to have done. Worked out well as it was less expensive than getting a rebuilt alt. Also, I knew what I was getting (sometimes rebuilt alts are bad out of the box or fail quickly).

I would keep the alt around as you may want to rebuild it in the future.

 

Yeah, if connections and grounds are good, a bad rectifier inside the alt is a likely cause. That, or you've got a winding that opened. Either way, take the alt in for testing, which is usually free.

 

I don't think it got wet, but as it seems, at least in my recent experiences, connections easily go bad in heavy moisture.

Ex: fusible links, engine ground, fuel pump wiring... etc.

I was thinking a bad connection internally only b/c the alternator seems to be working as soon as the rpm increase even a little, which (guessing) the voltage can then jump whatever the bad connection is...???

Well, I messed up the shaft removing the double pulley, so I'm not going to find out w/this one.