Checked wiring,fine. Slapped new 140A alt on and have not seen light since.
Battery Light! UGH!
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Battery Light! UGH!
My battery light is coming on in the mornings for up to about 14 miles. I am showing 13.2 to 13.6 volts with torque pro. The light hardly ever comes on in the afternoon, but sometimes. I had the batteries and alternator tested yesterday at Advance Auto parts. Alternator showed good both times they tested it. Batteries showed at or just above their rated cranking amps. I have inspected both negative grounds from the batteries, the engine ground from the firewall to the passenger side back side of the engine, and the body ground on the passenger side to the frame. They look great, tight, and have not moved in a long time. I added a cable from the alternator to the fender well and it showed about 7 amps while idling before dropping to about 4.5 amps.
I am thinking of still buying a new alternator anyway. That is the only think I can think of. Worse case, I just have a spare in the back of the truck. Any thoughts?
I am thinking of still buying a new alternator anyway. That is the only think I can think of. Worse case, I just have a spare in the back of the truck. Any thoughts?
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Joined: Jan 2015
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I fought with a battery light for a few weeks. Did everything you did to check everything. Even took the alternator out and at it tested on the Bench at oreily and it passed. Ended up changing it and the battery light hast came back on in months. I got mine at orielys for 170.
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As best I can tell there are 2 circuits in the voltage regulator if they show a certain amount of difference the light will be thrown but will still test good output.
I can only assume that a greater spread it would affect output and fail the test.
Who knows for shure.
I can only assume that a greater spread it would affect output and fail the test.
Who knows for shure.
Post Fiend
Joined: Aug 2007
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From: At the Station
I too have this issue. Battery light came on Friday towing the camper, Scan Gauge showing 10-11 volts. Swapped new alternator voltages now showing 13-14 volts but the light is still coming on. Voltages have not dropped according to gauge
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Lead Driver
Joined: Feb 2011
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From: L.A. (Lower Alabama)
Here are a couple of other considerations.
Checking Ripple Voltage
Ripple voltage or (AC voltage) can be measured by switching your DMM to AC and connecting the black lead to a good ground and the red lead to the "BAT" terminal on the back of the alternator, (not at the battery). A good alternator should measure less than .5 VAC with the engine running. A higher reading indicates damaged alternator diodes.
Alternator Leakage Current To check alternator diode leakage, connect the multimeter in series with the alternator output terminal when the car is not running. Leakage current should be a couple of milliamps at most; more often, it will be on the order of 0.5 milliamps. Use care when disconnecting the alternator output wire; make sure the battery is disconnected first.
Checking Ripple Voltage
Ripple voltage or (AC voltage) can be measured by switching your DMM to AC and connecting the black lead to a good ground and the red lead to the "BAT" terminal on the back of the alternator, (not at the battery). A good alternator should measure less than .5 VAC with the engine running. A higher reading indicates damaged alternator diodes.
Alternator Leakage Current To check alternator diode leakage, connect the multimeter in series with the alternator output terminal when the car is not running. Leakage current should be a couple of milliamps at most; more often, it will be on the order of 0.5 milliamps. Use care when disconnecting the alternator output wire; make sure the battery is disconnected first.
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Joined: Jul 2005
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From: Middle Tn.
Here are a couple of other considerations.
Checking Ripple Voltage
Ripple voltage or (AC voltage) can be measured by switching your DMM to AC and connecting the black lead to a good ground and the red lead to the "BAT" terminal on the back of the alternator, (not at the battery). A good alternator should measure less than .5 VAC with the engine running. A higher reading indicates damaged alternator diodes.
Alternator Leakage Current To check alternator diode leakage, connect the multimeter in series with the alternator output terminal when the car is not running. Leakage current should be a couple of milliamps at most; more often, it will be on the order of 0.5 milliamps. Use care when disconnecting the alternator output wire; make sure the battery is disconnected first.
Checking Ripple Voltage
Ripple voltage or (AC voltage) can be measured by switching your DMM to AC and connecting the black lead to a good ground and the red lead to the "BAT" terminal on the back of the alternator, (not at the battery). A good alternator should measure less than .5 VAC with the engine running. A higher reading indicates damaged alternator diodes.
Alternator Leakage Current To check alternator diode leakage, connect the multimeter in series with the alternator output terminal when the car is not running. Leakage current should be a couple of milliamps at most; more often, it will be on the order of 0.5 milliamps. Use care when disconnecting the alternator output wire; make sure the battery is disconnected first.
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I replaced the alternator with a new 140 amp from Advance Auto. The brand is Tough One. My Torque pro was showing 14 after 2 minutes (which is about 14.4 at the battery).
I will know in the morning on the way to work if it fixed the battery light problem, but I feel good about it.
I will know in the morning on the way to work if it fixed the battery light problem, but I feel good about it.
Tuned
Joined: Mar 2007
Posts: 485
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From: Timmonsville
I replaced the alternator with a new 140 amp from Advance Auto. The brand is Tough One. My Torque pro was showing 14 after 2 minutes (which is about 14.4 at the battery).
I will know in the morning on the way to work if it fixed the battery light problem, but I feel good about it.
I will know in the morning on the way to work if it fixed the battery light problem, but I feel good about it.
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I always use Internet coupons at advance auto. That's why I buy everything there. But I always go to retailmenot.com to see what coupon codes are available first. Many times there are $40off of $100 or $50 off of $125. Since the Alternator was over $150, then $50 is the max savings anyway.
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2 days in a row with NO battery light. I think the alternator was the problem. Thank You All, for the help. We are off to Yellowstone in a week!! Hopefully I don't have to come home with a new truck!! Haha
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