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2G Intermittent alternator charging

Droo

Probationary Member
3
1
Jan 30, 2022
Vancouver, BC_Canada
Pretty stumped on what could be causing this issue. Long story short, alternator had “died” on me last week. Replaced the alternator, and everything seemed to be fine and getting 13.6V , but when I went out for the second drive, the car was getting 11.8V just running on battery power, light on the dash comes on as well. It’s important to know, sometimes the car will start and run with 13.6V after the 2nd or 3rd try, and it will run like that until I turn the car off and try to start it again, which then it will run off battery power until I get lucky.

Battery is 2 months old, all the connections are clean. I do have all my grounds hooked up, even added some extra ones. Alternator fuse is good, even bypassed it to see if it would solve the issue to no avail. Nothing in the power wire from the alternator to the battery seems like it’s shorting out.

Alternator that was put in the car was a working AC Delco reman. And it is relocated with the Jay Racing kit, so heat isn’t really a big concern.

Any ideas or suggestions would be great.

Thanks, Duncan.
 

nismojones

10+ Year Contributor
124
35
Jan 10, 2008
Eastpointe, Michigan
Well it’s ECU controlled, I remember reading that you can safely run it without the (green?) wire that signals it to charge- you’ll have to look it up, I forget the color. Obviously if its consistent after that you might want to have the ecu checked.lt still could be a faulty Alt though, remanned are always hit or miss
 

waltah

Proven Member
369
154
Mar 2, 2011
fairfield, Virginia
Pretty stumped on what could be causing this issue. Long story short, alternator had “died” on me last week. Replaced the alternator, and everything seemed to be fine and getting 13.6V ...

Voltage at the battery after starting should be over 14. 14.4 or so, depending on the age of the battery.

It sounds like you have a charging system problem that is not the alternator. If so, you'll have to troubleshoot. First steps would be to measure the voltage drop from the BAT terminal on the alternator to the + terminal on the battery and the drop from the alternator frame to the - terminal on the battery: Do this by turning on the headlights for a minute or so to get a partial discharge, then starting the engine. These drops should be no more than a fraction of a volt.

The Eclipse charging system will compensate for some voltage drop but there's a limit to that. A loose connection or bad ground on the alternator frame might be too much.
 

TheFlashDSM

Supporting Member
1,075
275
Feb 18, 2010
stony brook, New_York
in 1 day, i had 4 2g dsm reman alternators fail on me.... then i went Galant alt route, direct bolt in. issue solved. next for my racecar I'm using a Saturn alt. and i must say the Saturn alt. has the most stable and consistent voltage at 14.3-.14.5
 

luv2rallye

DSM Wiseman
8,401
1,176
Jun 7, 2003
Minneapolis, Minnesota
IMHO reman alts have always been junk (and not even worth their "lifetime" warranty when they keep going out). Either get a new one or a rebuilt one from a alt/starter repair shop. And yes alts should be putting out 14.4V.
 

Droo

Probationary Member
3
1
Jan 30, 2022
Vancouver, BC_Canada
Well it’s ECU controlled, I remember reading that you can safely run it without the (green?) wire that signals it to charge- you’ll have to look it up, I forget the color. Obviously if its consistent after that you might want to have the ecu checked.lt still could be a faulty Alt though, remanned are always hit or miss
Car is running a brand new Link G4X, so I’m not entirely sure if it’s the ECU. If it was that would be a real bummer.
Voltage at the battery after starting should be over 14. 14.4 or so, depending on the age of the battery.

It sounds like you have a charging system problem that is not the alternator. If so, you'll have to troubleshoot. First steps would be to measure the voltage drop from the BAT terminal on the alternator to the + terminal on the battery and the drop from the alternator frame to the - terminal on the battery: Do this by turning on the headlights for a minute or so to get a partial discharge, then starting the engine. These drops should be no more than a fraction of a volt.

The Eclipse charging system will compensate for some voltage drop but there's a limit to that. A loose connection or bad ground on the alternator frame might be too much.
I’ll give that test a shot tomorrow and see what happens. All of my grounds and connections are clean and solid, I’m not too worried about that.
in 1 day, i had 4 2g dsm reman alternators fail on me.... then i went Galant alt route, direct bolt in. issue solved. next for my racecar I'm using a Saturn alt. and i must say the Saturn alt. has the most stable and consistent voltage at 14.3-.14.5
Yea that’s bad. I’ve read on forums here it’s something to do with the Remans rejecting the signal from the ECU when to charge? If I can’t find any other issue, my last ditch effort will probably be the Saturn alternator.
IMHO reman alts have always been junk (and not even worth their "lifetime" warranty when they keep going out). Either get a new one or a rebuilt one from a alt/starter repair shop. And yes alts should be putting out 14.4V.
What confused me was the alternator that I put in the car, was a used AC delco reman off an old 2g of my brothers. It worked fine from the time it was ran on the car. Just seems odd that it is “on” or “off”. I could just be really unlucky, but I’ve yet to see any other noticeable problems with the charging system. Probably just going to throw a Saturn alternator in and see what happens.
 

GSXRunner

Proven Member
153
37
Feb 24, 2013
Queens, New_York
I'm still running the original stock alternator. Two times it failed, once I had to replace the voltage regulator (I think around $10 on ebay) and maybe a year or two ago, I had to replace the brushes ($5 on Amazon). It's really easy and cheap to rebuild the alternator as long as you don't fry the stator or the rotor.

You should have over 14 volts when the engine is running. If you're getting less, it could be that your battery is a bit drained. Put the battery on a charger overnight and then start it and check the voltage. If it's still not 14 volts or more, check all your grounds for voltage drops. You can do this with a voltmeter by connecting one probe to negative terminal of battery and the other to the chassis and engine at various points looking for a voltage drop. I believe there are 4 chassis/engine grounds. Turn on all your accessories such as lights and blower to increase current flow through the grounds; this will show a big voltage drop (more than 200mv) if a ground is bad. Also check for a voltage drop between battery positive and alternator positive.

If you still haven't found anything, check the connector to the alternator. Make sure there is no corrosion; I had this problem once before and with a little cleaning, my problem was solved.
 
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