Weird electrical issue - Brakes hit = power loss Options

[k-weaver]

Alright guys so here is the story...

I was on my way to work this morning and everything seemed fine. I hit my brakes to slow down for a corner and right as I did so my stereo turned off, my clock reset, and the car stuttered for like a half a second. After a brief "what the hell was that?" I turned off my radio (thinking this was a possible cause) and kept driving. The rest of the entire drive I noticed my dash lights (more so my clock) would dim ever time I hit the brakes. Its as if the voltage is dropping drastically for a split second but then going back to normal.

I've yet to do any troubleshooting as I'm currently at work. Just wanted to see if anyone had any idea's that I could try out once I get home.

[RabidTRD]

Bring your car to an Advance Auto Parts or a Autozone and have the alternator tested. It sounds like your starting to see signs of strain.

Have them test the alt, battery, and to see if there is a drain on the system (with an amp clamp), because it could also be something shorting out. Luckily our cars electrical systems are pretty simple, so a resolution shouldnt be too hard to find.

And one more thing to check, see if your brake light switch may be pressed up against the firewall. If the wires have been crushed fir long enough, they may have worn through the conduit and are contacting the firewall as you press. Usually this would result in a blown fuse, but it's something to check as well. Your brake light switch is located behind your brake pedal in a bracket near the base of the pedal. Looks like a white box with a nipple sticking out.

This post has been edited by RabidTRD: Oct 17, 2011 - 11:57 AM

[k-weaver]

man...I can't tell you how many alts i've gone through. First time I went through Kragen (now o'rielys) and got the one with a lifetime warranty. If it is that (again!) I should be able to get a replacement at no cost. Still sucks though. Thanks for the advice, i'll probably head over to autozone after work.

[stephen_lee]

I would also look into the battery clamps and grounds, which would be my first thing to suspect

[k-weaver]

I would also look into the battery clamps and grounds, which would be my first thing to suspect

Any specific grounds? The terminals themselves should be good (i'll double check) as I used the gold plated for the positive (no corrosion issues). A long time ago I swapped out the ground cable from the batt to the chassis with a 4awg wire. I wonder if it may have come loose. These are great suggestions guys, keep 'em coming!!

[stephen_lee]

battery and alt wiring.

grounds to engine.

these are the easy things i'd check first. but chances are its the alt as TRD said

[Batman722]

nm

This post has been edited by Batman722: Oct 17, 2011 - 8:52 PM

[RabidTRD]

Going through alts like that, do you have a sound system?

[cjh4l22]

^if so, look into higher output alts. I found one that ouputs 165amps. <-ftw

[k-weaver]

Going through alts like that, do you have a sound system?

I do but i've been fairly conservative since the last replacement. I've got a 4 channel amp for the highs and a really old Kicker amp for my subs (2MTX Thunder 7500). I think i'm on my 5th alt since I purchased the car which has been about 5 years. So I guess i end up replacing them once a year.

So I had everything tested and it came back fine. I'm wondering if this is the beginning stages of it going bad, works one minute, fails the next. When I got home I hooked up my multimeter. Batt is just above 12v sitting. Car on it hits about 13.2-13.4. I also put the meter on the alt and it was at 13.8. I watched the voltage as I tapped the brakes (multiple times) and you can see the dome light dim and e-brake light on the dash dims and the red light on the door dims every time I hit the brakes. Voltage however only dropped like .02. I can't see this small amount causing the dimming situation.

[stephen_lee]

grounds and clean the contacts on the alt & battery +

put the mulitmeter between the alt + post and the battery + with engine running and lights on, should have less than .3 on the meter.

then put one lead to the battery - and the other on the alt casing.. again running with lights on, should read less than .2

mine are .15 for the + and .1 for grounds

[dudeofchaos]

Have you unplugged the dash fuse?

[mkernz22]

Well I can say the almost the same thing happens when I hit the brakes on my car, but instead of everything shutting down, my headlights dim a tad bit. I have no sound system in the car, but I was thinking that the power that the brake lights use might cause this to happen.

[stephen_lee]

I notice a bit of a drop in voltage too. we have a lot of lights back there lol so...

but it shouldnt cause the engine to stumble. you may have loose wiring somewhere

[k-weaver]

grounds and clean the contacts on the alt & battery +

put the mulitmeter between the alt + post and the battery + with engine running and lights on, should have less than .3 on the meter.

then put one lead to the battery - and the other on the alt casing.. again running with lights on, should read less than .2

mine are .15 for the + and .1 for grounds

I'll try this tonight and see the results.

[k-weaver]

I think I may have found the issue....

A long time ago I installed those reverse glow gauges (purchased on ebay). To get power I spliced into one of the wires that plug into the gauge cluster. I don't recall the color but if i'm not mistaken its the only wire that provides power when the headlights are turned on and also the brights (one of wires cuts power when the brights are on). The gauges worked fine for a really long time then one day they were intermittent where they would work one second and not work the next. Finally one day they stopped working altogether.

Took me a while to realize it but the issue with my dimming situation / radio turning off / car almost dying only started once my gauges started working again. Thinking the gauges were the cause (due to how I powered them and the fact that work 25% of the time) I purchased another set and replaced only the little black box that everything plugs into (if you ever installed them you know what I'm talking about). Turns out this may have been the cause. My gauges are once again working. My radio no longer turns off when I hit the brakes and the car doesn't stutter. I wonder if something was shorting out in that box?

I still have an issue with the dimming but from other posts it sounds like this is normal? When I replaced the box for the gauges I first completely unplugged it and tested the car, lights still dimmed when brakes pressed. So i'm confident the gauges aren't the cause of the dim.

I drove last night to the store and this morning to work with everything on (headlights and radio) and didn't have any issues. I'm not 100% sure that the issue is fixed but at least its better.