"G" light on dash is on....
Thread Starter
Advanced
Joined: Mar 2009
Posts: 85
Likes: 0
From: johnstown PA
"G" light on dash is on....
My 76 911 had a bad alternator when I bought it several months ago. It tested with no voltage output. After receiving three incorrect alternators from three different parts dealer, I finally got the correct one and installed it. The new alternator, according to my local mechanics, is performing as it should and it's charging correctly at the battery but my "G" light on the dash is still ON all the time. I'm wondering why that light would be on if the alternator is working correctly??? Is there any other reason that this light would be on all the time?????
Team Owner
Joined: Aug 2005
Posts: 28,478
Likes: 1,632
From: Cambridge Ontario Canada
also if it is an updated alternator you have to put a resistor in parallel with the light I think. the first thing I would do however is measure the output at the battery. see if you have at least 13v. if you don't then you are not generating the excitement voltage needed. I think your car has an external regulator does it not ? has the car been updated ?
Thread Starter
Advanced
Joined: Mar 2009
Posts: 85
Likes: 0
From: johnstown PA
I'm not sure what updating is for this 76 but the new alternator does have an internal regulator.as did the previous one. It is getting a good voltage to the battery....14 volts at idle and 13.5 at 2000RPM. I'm really new to these cars but I'm willing to plug along to get this one working well. All three connections on the alternator are tight and secure. Thanks for the comments so far......
Team Owner
Joined: Aug 2005
Posts: 28,478
Likes: 1,632
From: Cambridge Ontario Canada
okay well it has definitely been updated if it has an internal regulator .. and we Know the voltage is good from the alternator .. it has to be in the wiring .. so we need to back up a little ..
so when did the light first come on .. did you by the car with the light on ? someone needs to provide this guys with a schematic of an updated car . i wonderif the wiring was done correctly when it was updated ....
I just posted a link to the update rocedure a little while back .. I think there is a wire off somewhere, or in the wrong spot.
so when did the light first come on .. did you by the car with the light on ? someone needs to provide this guys with a schematic of an updated car . i wonderif the wiring was done correctly when it was updated ....
I just posted a link to the update rocedure a little while back .. I think there is a wire off somewhere, or in the wrong spot.
Thread Starter
Advanced
Joined: Mar 2009
Posts: 85
Likes: 0
From: johnstown PA
The light was on when I bought it. I replaced the alternator and made the connections as on the original one. The large ground wire was connected to the bolt on the left side of the fan housing and to the engine....That's the way it is now. Is there a change that needs to be made to the dash "G" light???
Trending Topics
I haddah Google dat
Rennlist Member
Rennlist Member
Joined: Nov 2008
Posts: 11,501
Likes: 5
From: Fresno, CA
If you know how to test for voltage drop, check the cable going to the starter from the alternator at the starter end. Might want to have the alternator tested also. You have to take it to an alternator shop that will spin it and test it, not static test it.
Rennlist Stories
The Best Porsche Posts for Porsche Enthusiasts
Porsche's Top 5 Most Questionable Naming Decisions
Verdad Gallardo
Pogea Racing's 964 Porsche 911 Reimagination Stands Out in a Crowded Field
Verdad Gallardo
6 Convertible Top MYTHS Most People Don't Understand!
Michael S. Palmer
2026 Porsche 911 Club Coupe is Spectacular, And Everything Wrong with the Porsche Market
Joe Kucinski
Talos Takes Your 991 Porsche 911 GT3 to the Next Level for a Cool $1.13 Million
Verdad Gallardo
9 Vehicles Porsche Helped Engineer that Aren't Porsches
Verdad Gallardo
9 Features and Characteristics That Only Porsche People Understand
Verdad Gallardo
I've Written 500 Rennlist Articles: Here's How Porsche Has Changed Along the Way
Joe Kucinski
10 Most Unnecessary Porsches Ever Built (And Why We Love Them)
Verdad Gallardo
Team Owner
Joined: Aug 2005
Posts: 28,478
Likes: 1,632
From: Cambridge Ontario Canada
Well he is getting 14 volts so the alternaor is definitely putting out ... Do a search here or on pelican for the alternator update. there is a artcicle stating whayt needs to be done. i think ther is a wire that goed from the alternator right to your light... I wil look over my bentley but i have an external regulator.
I haddah Google dat
Rennlist Member
Rennlist Member
Joined: Nov 2008
Posts: 11,501
Likes: 5
From: Fresno, CA
I could be wrong, but the diodes could be burned up. It's been a long time since I had my factory manual (can't find the set for some reason), but I think if you disconnect the battery with the engine running, the diodes can be damaged. But don't quote me on that.
Could also be a faulty regulator. I think it's time to get out the multimeter and actually go through it methodically. Use the volt setting, not ohm setting when testing voltage drop.
Could also be a faulty regulator. I think it's time to get out the multimeter and actually go through it methodically. Use the volt setting, not ohm setting when testing voltage drop.
Thread Starter
Advanced
Joined: Mar 2009
Posts: 85
Likes: 0
From: johnstown PA
The Alternator is a rebuilt one right off the shelf from Gernam Auto Dismantlers. The regulator should be good and again it's putting out and doing it's job at the battery. I can't figure that if the alternator is rebuilt, getting good voltage to the battery, the battery is fully charged,.....but....the light is still on.....
