This is weird
Thread Starter
Race Director
Joined: Oct 2011
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From: Dallas Texas
2025 C4 of the Year Finalist - Modified
This is weird
When I turn on my HID fog lights, the rpm drops and feels like it wants to stall but doesn't. I've had HID fogs for 3 years and never had this problem till last week. I last drove the car Sunday night. Checked battery voltage with my multimeter this morning, and it read 12.48 volts. It doesn't do anything when I turn the AC on as far as a drop in rpm. 93 LT1
What should I be checking?
What should I be checking?
Le Mans Master
Joined: Sep 2013
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From: near the thumb in the mitten
Battery should read 12.6v with the doors closed and everything off. 12.48 corrosion at battery terminals? I would go by the auto parts store for a free electrical system test. Verify battery and charging systems are 100%. If you have an inductive amp clamp you could see how may amps hid draw. If using a digital meter be careful not to blow fuse.
Thread Starter
Race Director
Joined: Oct 2011
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From: Dallas Texas
2025 C4 of the Year Finalist - Modified
Terminals are clean. Would I have to remove the batter and alternator for an electrical test? Not that I can't, it would just be an annoyance. But if I have to oh well.
Thread Starter
Race Director
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From: Dallas Texas
2025 C4 of the Year Finalist - Modified
Zen Vet Master Level VII
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From: Southlake, TX
Thread Starter
Race Director
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From: Dallas Texas
2025 C4 of the Year Finalist - Modified
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Burning Brakes
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From: Buchanan GA
I am spoiled with having the ability to measure DC amp draw. Got a buddy with an amp clamp for DC? Voltage drop is a good indicator of elevated amp draw.
What size fuse protection is on the lights? Hard to think that they would be putting enough current draw out that they would load the alternator to the point of dragging down the motor.
What size fuse protection is on the lights? Hard to think that they would be putting enough current draw out that they would load the alternator to the point of dragging down the motor.
Thread Starter
Race Director
Joined: Oct 2011
Posts: 16,089
Likes: 819
From: Dallas Texas
2025 C4 of the Year Finalist - Modified
I am spoiled with having the ability to measure DC amp draw. Got a buddy with an amp clamp for DC? Voltage drop is a good indicator of elevated amp draw.
What size fuse protection is on the lights? Hard to think that they would be putting enough current draw out that they would load the alternator to the point of dragging down the motor.
What size fuse protection is on the lights? Hard to think that they would be putting enough current draw out that they would load the alternator to the point of dragging down the motor.
What do you mean by elevated amp draw? I agree! Wouldn't running the AC put out more current draw than turning on hid fog lights? I never put bigger fuses for the fogs. The ballasts are cheap ones. I'm surpsused they have lasted this long. But yeah, happens when I turn the fogs on. Makes me wonder if something with the ballasts is going on.