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Touching Brakes Causes at least 1 volt loss (where is brake ground?)

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Old Sep 24, 2004 | 03:43 PM
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pianoprodigy's Avatar
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Touching Brakes Causes at least 1 volt loss (where is brake ground?)

So, I just noticed today in paying close attention to my voltage on both my Microtech Display and on my turbo timer that I am losing at least 1 volt when I step on the brakes. I'm thinking this is a grounding issue. Revs are NOT dropping, just voltage. Where is the ground for the brake lights? I'm sure I could find it if I went looking, but I would rather just know ahead of time.

Thanks,

Alan

Last edited by pianoprodigy; Sep 24, 2004 at 03:49 PM.
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Old Sep 24, 2004 | 04:37 PM
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Yes, I notice it in the A/F Guage aka the disco light. It shifts one down if I hit the brakes.
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Old Sep 24, 2004 | 06:11 PM
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Yep, at a stop it happens even more. You can see lights dim too. Maybe another issue though. Just thought I would chime in.
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Old Sep 24, 2004 | 06:13 PM
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mine does it too
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Old Sep 24, 2004 | 08:17 PM
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FYI, the brake lights pull an astounding 163W total. That's worse than having headlights on.

Just about every car I've ever driven, new and old, has had some amount of dimming of the interior lights when the brake lights come on... except for the cars with much more effecient LED brake lights. At a higher idle, it's less noticable.

If it's REALLY bad, I'd look at the grounding of the alternator/battery. A bad ground on the brake lights themselves would only cause them to dim and actually pull less current.

Rev the car up to a higher "idle" rpm (say 1.5-2k) and see if the effect lessens.

That big-*** battery-draining subwoofer setup ain't helpin' either!
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Old Sep 24, 2004 | 08:21 PM
  #6  
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Originally Posted by InsaneGideon
FYI, the brake lights pull an astounding 163W total. That's worse than having headlights on.

Just about every car I've ever driven, new and old, has had some amount of dimming of the interior lights when the brake lights come on... except for the cars with much more effecient LED brake lights. At a higher idle, it's less noticable.

If it's REALLY bad, I'd look at the grounding of the alternator/battery. A bad ground on the brake lights themselves would only cause them to dim and actually pull less current.

Rev the car up to a higher "idle" rpm (say 1.5-2k) and see if the effect lessens.

That big-*** battery-draining subwoofer setup ain't helpin' either!
Im aware of that, is there an LED kit or conversion possible for the FD? Maybe the brakes have bad grounds? Grounds helps but still doesnt help as much.
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Old Sep 24, 2004 | 08:29 PM
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From: SoCal
Originally Posted by Fatman0203
Im aware of that, is there an LED kit or conversion possible for the FD? Maybe the brakes have bad grounds? Grounds helps but still doesnt help as much.
A bad ground on the brake lights only affects the brake lights. If we disconnected the ground on the brakes altogether, the voltage drop problem wouldn't exist.

I think there is an LED kit or two out there; have a look in the interior/ext./audio section. I remember a thread that linked to a Japanese site. The FD set looked cheesy, but they had a Lamborghini conversion ()that looked quite nice (IMO), as they used a very dense packing of LEDs.

I'm not sure how much power/current the replacement LED sets actually use, I've just been in a couple of newer vehicles equipped with them and stated my observation. They're "typically" more effecient, unless, of course, they're using a gillion LEDs to offset the power/effeciency gains.
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Old Sep 24, 2004 | 08:32 PM
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Ya that would be my problem I really wouldnt want to lose that look. Are there maybe more efficient replacement bulbs? *sigh* always something with the FD.
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Old Sep 24, 2004 | 08:47 PM
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Well, you could go with lower powered bulbs and risk having dimmer lights.

Once you've reached the limit of replenishing grounds/ powerfeeds with beefed up wires and what not, look at the battery. As they age, they often raise in internal resistance, so a large current draw will cause more voltage drop.

The alternator may be on it's way out too, but I think that's what PianoProdigy is trying to figure out, judging from his other thread. I can't say anything on that, as I don't have specs on the unit. It may be crapping out, or may be intentionally regulated to deliver lower currents at lower RPM, thus making the car rely on the battery. I don't know for sure.

I'm not exactly sure what the specs on the alternator and battery are down to the point where I, or someone else, could engineer a solution. To start, I'd have to break out a few current meters, and quite frankly I'm too lazy.

Last edited by InsaneGideon; Sep 24, 2004 at 08:50 PM.
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Old Sep 25, 2004 | 12:45 AM
  #10  
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Originally Posted by InsaneGideon
To start, I'd have to break out a few current meters, and quite frankly I'm too lazy.
Same, maybe when someone gets a new battery they can report back.
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Old Sep 25, 2004 | 12:48 AM
  #11  
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Look what I found on google
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