Dim Alternator Light
Thread Starter
Safety Car
Joined: Mar 2005
Posts: 3,503
Likes: 2
From: Raleigh NC
Dim Alternator Light
My alternator light is just barely glowing. Voltage is reading a bit low, 13.2V.
I checked the belt tension and connections.
I don't know where else to look; except here for advice.
SPECS:
Alternator: New 140A Powermaster
Wiring: All new 4ga wire and connectors
Voltage: 13.2v
Battery seems nice and charged.
My Charging System Grid is a bit unconventional, but I don't see where this setup would cause this problem. Please correct me if I did wrong here:
I checked the belt tension and connections.
I don't know where else to look; except here for advice.
SPECS:
Alternator: New 140A Powermaster
Wiring: All new 4ga wire and connectors
Voltage: 13.2v
Battery seems nice and charged.
My Charging System Grid is a bit unconventional, but I don't see where this setup would cause this problem. Please correct me if I did wrong here:
Last edited by PhotoVette1; Feb 3, 2007 at 07:19 PM.
Racer
Joined: Dec 2006
Posts: 417
Likes: 40
From: Swansea IL
Bad Diode
I think that Clint has hit is on the head. Either a diode in the rectification bridge is leaking or your voltage regulator (I am assuming that the ALt has an internal regulator) has a bad ziner diode on Tr2.
A good alternator should put out 13.8-14.2 volts once the engine is just started.
Bob
A good alternator should put out 13.8-14.2 volts once the engine is just started.
Bob
Thread Starter
Safety Car
Joined: Mar 2005
Posts: 3,503
Likes: 2
From: Raleigh NC
I think that Clint has hit is on the head. Either a diode in the rectification bridge is leaking or your voltage regulator (I am assuming that the ALt has an internal regulator) has a bad ziner diode on Tr2.
A good alternator should put out 13.8-14.2 volts once the engine is just started.
Bob
A good alternator should put out 13.8-14.2 volts once the engine is just started.
Bob
Are they garbage or am I just unlucky?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
Do you have anything unusual in the electrical system...like a high wattage stereo amp? If you are drawing excessive current, you could be blowing the diodes. [Big bass speakers draw a lot of current spikes that you won't see on the ammeter.]
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
If it's an SI style Powermaster, just give up on it and install a CS144. SIs were never designed to handle that much power.
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Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
A DIM alt/gen light is frequently caused by reversing the leads going into the regulator.....nothing to do with main stud output wiring....
EXCEPT when viewing from the rear of the alt....the MOST CLOCKWISE wire will allways have system voltage on it.....even when key is off, car parked.....
when key is in the run position , AND THE ENGINE IS RUNNING is the ONLY time the second wire will have voltage on it, what happens is the regulator pulls that wire to ground to light the bulb.....
what can happen is if the wires are reversed is when engine is running, the bulb acts to activate the reg as if it was the system wire....fed NOW through the ignition ON position of the sw.....light glows dim....
this is a frequent wiring error when replacing the connector, a famous item, and the color codes and wiring age sure as hell don't make it any easier.....
ask me how I know all this.....
EXCEPT when viewing from the rear of the alt....the MOST CLOCKWISE wire will allways have system voltage on it.....even when key is off, car parked.....
when key is in the run position , AND THE ENGINE IS RUNNING is the ONLY time the second wire will have voltage on it, what happens is the regulator pulls that wire to ground to light the bulb.....
what can happen is if the wires are reversed is when engine is running, the bulb acts to activate the reg as if it was the system wire....fed NOW through the ignition ON position of the sw.....light glows dim....
this is a frequent wiring error when replacing the connector, a famous item, and the color codes and wiring age sure as hell don't make it any easier.....
ask me how I know all this.....
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Racer
Joined: Nov 2005
Posts: 339
Likes: 0
From: San Jose CA
A DIM alt/gen light is frequently caused by reversing the leads going into the regulator.....nothing to do with main stud output wiring....
EXCEPT when viewing from the rear of the alt....the MOST CLOCKWISE wire will allways have system voltage on it.....even when key is off, car parked.....
when key is in the run position , AND THE ENGINE IS RUNNING is the ONLY time the second wire will have voltage on it, what happens is the regulator pulls that wire to ground to light the bulb.....
what can happen is if the wires are reversed is when engine is running, the bulb acts to activate the reg as if it was the system wire....fed NOW through the ignition ON position of the sw.....light glows dim....
this is a frequent wiring error when replacing the connector, a famous item, and the color codes and wiring age sure as hell don't make it any easier.....
ask me how I know all this.....
EXCEPT when viewing from the rear of the alt....the MOST CLOCKWISE wire will allways have system voltage on it.....even when key is off, car parked.....
when key is in the run position , AND THE ENGINE IS RUNNING is the ONLY time the second wire will have voltage on it, what happens is the regulator pulls that wire to ground to light the bulb.....
what can happen is if the wires are reversed is when engine is running, the bulb acts to activate the reg as if it was the system wire....fed NOW through the ignition ON position of the sw.....light glows dim....
this is a frequent wiring error when replacing the connector, a famous item, and the color codes and wiring age sure as hell don't make it any easier.....
ask me how I know all this.....
Hmmm...I wonder if this is the cause of my battery light coming on only during idle and the engine is warm. During cruise, the light turns off. It also turns on briefly under heavy acceleration.
Thread Starter
Safety Car
Joined: Mar 2005
Posts: 3,503
Likes: 2
From: Raleigh NC
After--but also after I replaced the whole charging system from nose to tail.
I'm gonna solve this problem when I get up in the morning. I'm not leaving the garage til it's settled. This is betwixt me and my C3, so stand clear.
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Close. The engine does not need to be running. That circuit has voltage the moment you turn the key on.
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
