• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

charging problem

  • Thread starter Thread starter BPH90LX
  • Start date Start date May 6, 2006
B

BPH90LX

New Member
Apr 18, 2005
19
0
0
May 6, 2006
#1
  • May 6, 2006
  • #1
I just upgraded to a 3G alternator and dont seem to be getting enough charge from it. I was already having a electrical problem where it wouldnt turn over except when jumped. It would stay running but wouldnt restart. I have changed out the battery, cables, and starter solenoid besides the alternator. I checked all the grounds and added a 4g ground from the block. The belt is tight and the 3g has a little smaller pulley the the old one. the battery shows 12.4v with the car off, 12v running, and dosen't go up any with RPM's. I also have the 4g power wire from the 3g to the solenoid and the B&w wire is hooked up, the black and orange's are not.
It starts and runs now but I'm thinking not for long without getting more volts, any ideas? Thanks
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
33
129
May 6, 2006
#2
  • May 6, 2006
  • #2
If the wiring is sound, have you had the alt bench tested to make sure it's good?

It looks like you arent getting any output from the alt.

Good luck.
 

302RollinHard

New Member
Sep 26, 2005
0
0
0
Columbus, OH
May 6, 2006
#3
  • May 6, 2006
  • #3
Isn't there a pin (most of the time plastic) in some cases that is installed in the back of the alternator to retain the brushes during assembly?? This is a thought if the alternator is new or a fresh rebuild. Take a look. Or it could just be a dud.
 
B

BPH90LX

New Member
Apr 18, 2005
19
0
0
May 6, 2006
#4
  • May 6, 2006
  • #4
There was no pin holding the brushes in but I checked and dont have any power on the ignition switch wire. Does that mean it just needs replacing to get the alternator charging?
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
33
129
May 6, 2006
#5
  • May 6, 2006
  • #5
Which ignition switch wire doesnt have power? I got an idea but wanted to ask first.
 

Saleen0679

10 Year Member
Apr 14, 2005
876
24
49
Yakima, WA
May 6, 2006
#6
  • May 6, 2006
  • #6
The ignition switch is part of the regulator voltage control switching circuit so it could very well prevent the alternator from charging.

If you have multiple problems that involve the ignition switch like it sounds, it is inexpensive enough to eliminate by replacement if you don't want to spend the time troubleshooting.
 

Skoobie

Damn...Tyler65's hot!
May 25, 2003
655
0
17
Vancouver, WA
May 6, 2006
#7
  • May 6, 2006
  • #7
Not sure whats going on but you should be getting more than 12v while running. I get 14.5-14.9 at idle. I think thats pretty much the norm. Either you have a bad connection or you got a semi-bum alt
 
B

BPH90LX

New Member
Apr 18, 2005
19
0
0
May 6, 2006
#8
  • May 6, 2006
  • #8
No power on the green & red off the alternator that connects to the B&W from the factory harness
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
33
129
May 7, 2006
#9
  • May 7, 2006
  • #9
Saleen and I had the same thought.

If that red/green wire doesnt get power to the alternator, it wont charge. There is a ground circuit in the regulator. WHen the alt is not charging, the reg creates a ground for the far end of that red/grn wire (this ground allows the battery light to come on). WHen the alt is doing fine, the ground dissipates and the light goes out.

There is also a resistor in the circuit for the event that the battery light bulb burns out.

Saleen can probably explain a whole lot more coherantly than I can.

Good luck.
 
B

BPH90LX

New Member
Apr 18, 2005
19
0
0
May 7, 2006
#10
  • May 7, 2006
  • #10
IThe battery light never comes on, even when starting so I have a new ignition switch on the way. I hope that fixes it.
 
B

BPH90LX

New Member
Apr 18, 2005
19
0
0
May 19, 2006
#11
  • May 19, 2006
  • #11
The ignition switch was the problem, its charging now. Thanks
 
You must log in or register to reply here.

Similar threads

3
Electrical Starter solenoid out of space?
  • 387lx
  • Jan 22, 2026
  • Fox 5.0 Mustang Tech
Replies
3
Views
291
Fox 5.0 Mustang Tech Jan 23, 2026
387lx
3
C
Electrical HELP! 1989 5.0 Stick, Voltage Bleed onto Ignition Trigger wire
  • ChickenDeluxe
  • May 14, 2026
  • Fox 5.0 Mustang Tech
Replies
7
Views
125
Fox 5.0 Mustang Tech May 24, 2026
ChickenDeluxe
C
S
Electrical Alternator not charging after terminator 2 install.
  • Sfab79
  • Aug 24, 2025
  • Fox 5.0 Mustang Tech
  • 2
Replies
20
Views
535
Fox 5.0 Mustang Tech Aug 31, 2025
Sfab79
S
A
Resolved Electrical Help Please
  • Alabama
  • Jan 22, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
2
Views
236
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Jan 22, 2026
AeroCoupe
Electrical Ron Francis Headlight / Alternator Harness
  • dan50
  • Apr 30, 2026
  • Fox 5.0 Mustang Tech
Replies
0
Views
179
Fox 5.0 Mustang Tech Apr 30, 2026
dan50
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?