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Alternator not charging, dlc displays battery not charging

Tiny
PHILIP SICILIANO
  • MEMBER
  • 2004 CADILLAC ESCALADE
  • 6.0L
  • V8
  • 4WD
  • AUTOMATIC
  • 170,000 MILES
Hello, I was driving my truck and that amp gauge dropped to 12 volts. Dlc displays battery not charging I tested alternator with volt meter it is only showing what the battery is holding in charge. I replaced the alternator and I had the same issues again so I went out and bought another alternator and it is still doing the same thing. So I decided to get a test light and hook it up to the positive on the battery and I probed the brown wire on the three prong plug on the back of the alternator. And the alternator immediately starts charging and the dlc message goes away and the volt meter in car jumps to 14 volts. As soon as I remove the test light with the 12 volts the alternator stops charging. I have no wire diagrams. I did cut the brown wire thinking there was a break in it but it still did not work.
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Wednesday, July 31st, 2019 AT 1:42 PM

9 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Welcome to 2CarPros.

I think we have a power issue. When you put power to the brown wire, it is turning off the battery light, but I doubt it is charging the battery. What I need you to check first is the if there if there is power to the B+ wire on the alternator. That should have battery voltage all the time. If it doesn't, suspect a bad fusible link. Take a look at picture 1.

Picture 2 shows that the brown wire you are referring to. If you are going from the battery + that will turn off the battery light.

Let me know what you find.

Joe
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Wednesday, July 31st, 2019 AT 7:10 PM
Tiny
PHILIP SICILIANO
  • MEMBER
  • 6 POSTS
Thank you. I will look this weekend and let you know I appreciate your reply. Thanks for the schematics.
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Wednesday, July 31st, 2019 AT 8:24 PM
Tiny
PHILIP SICILIANO
  • MEMBER
  • 6 POSTS
Let me tell you this when I put the volt meter negative probe on the negative battery terminal and put the positive probe on the black line coming off the alternator it gives me voltage when the truck is running it stays at 12 volts and discharges slowly and the dlc lights up stating battery not charging. If I take the test light and connect to positive and probe the brown wire the dlc goes off and the volt meter starts to read 14 volts. As soon as I remove the probe from the brown wire the alternator stops charging and the voltage drops and the dlc comes back on saying battery not charging. I am hoping it’s not the computer.
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Wednesday, July 31st, 2019 AT 8:33 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
I'm not seeing a black wire on the schematic. Is there power to the alternator with the engine and key off?
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Wednesday, July 31st, 2019 AT 9:50 PM
Tiny
PHILIP SICILIANO
  • MEMBER
  • 6 POSTS
Yes, the voltage at the back of the alternator is the same voltage that the battery has. The alternator has the plug with 3 wires on the back along with a black wire with a connection that goes to the red battery box.
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Wednesday, July 31st, 2019 AT 10:04 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
The wire that you check that allows the alternator to work. Have you checked it for continuity?
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Thursday, August 1st, 2019 AT 6:48 PM
Tiny
PHILIP SICILIANO
  • MEMBER
  • 6 POSTS
I still haven’t had a chance to check it. I will definitely let you know. Thank you
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+1
Monday, August 26th, 2019 AT 2:11 PM
Tiny
PHILIP SICILIANO
  • MEMBER
  • 6 POSTS
I got it going. I just got to wrap everything up. I cut the number 15 wire close to the ECM ran a new wire from there to the alternator brown and now it’s charging no dlc or battery light. Thank you for your input.
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Monday, August 26th, 2019 AT 4:05 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Welcome back:

It must have been internally damaged. I'm glad you got it fixed. And if I was of any help, you are welcome. Let us know if we can help in the future.

Take care,

Joe
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Monday, August 26th, 2019 AT 5:41 PM

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