Headlights Flash When Brake Pedal Is Pressed

[sjc6765]

I have a '93 sc300,,, I am having some electrical problems,, when I have the headlights on, they flash or go dim when I step on the brakes, just for a second, then back to normal. Also, the A/C - Heater fan looses power, and cycles when the turn signals are on. I just put in a new alternator, it was doing this with the old one, so I thought the voltage regulator was going out. (internal to the alt) Has anybody come across this before,, or know whats going on?

Thanks for any help,, Steve.

[UCF3]

How old is you battery?

I haven't come across this before.

[sjc6765]

It was in the car when I got it 2.5 years ago. I am thinking the ground for the tail lights might be bad,, I only have this problem when I use the turn signals, or the brakes. Both use the tail lights,, and a bad ground back there would make a high amp draw, and cause the lights to dim for a second untill the alt catches up.

Does anybody know where the tail lights are grounded?

[sjc6765]

Just put in a new battery,, the problem is still there.

Anybody have any ideas on this,, or know where the tail lights are grounded?

[bremney]

HI! I had the same problem with my 92 sc400. The lights would flicker when the brake was pressed and also the dash would flicker with the signal light flashing ;) This really bothered me. I read back on many posts (thanks to all for great posting :D ) and found one or two that meantioned grounding. Well I first checked the battery, it was badly corroded. I cleaned that up and the problem was about 75% better. It was also mentioned on a post to check body grounding. Mine is badly rusted (Canadian car ) and that will be my next step to clean that up...I figure that should solve the problem.

[SKperformance]

Nothing to do with a taillight ground , try replacing the battery wires and terminals to the body and engine .

Did you get a new alternator or just put a new regulator in? So does it have the old coil and brushes?

[SC_COUTURE]

the more i read these forums the more sense all of my problems make lol i got the car a year ago and everything was fine for about a month....until one day i was driving the limit and the car just died in the middle of the road with the red battery light that came on...had the alternator replaced and it worked for a couple more weeks...then one day it did the same thing and the car almost died at a red light but i gave it gas and kept the car moving which got me home...then i had the battery replaced at canadian tire i figured even if it is a ground somewhere than i can at least drive it until i can diagnose the problem....the new battery was working but i felt pretty paranoid so i went back to canadian tire and got them to do a system charge check which includes the starter, the alternator and the battery. the alternator was fine as i expected since i had it replaced twice. turned out that the battery that they sold me was in the computer listed under 92 sc400 but that in reality it didnt even fit according to the measurements. they warrantied the battery for me and gave me a much more powerful one. they also replaced my battery terminals with marine ones for 20 bux because mine were from 1992!!! lol and they were corroded to sh*ttt. the whole thing cost me about $150 and ct promised that there is no short anywhere in the system. for now the car seems okay but i have a feeling that the problem is still not fixed and that once the battery dies the ground will show itself. i don't really understand how this works but it seems that everytime i replace the battery it works for a bit and then one day the light comes on and im calling a cabbie to get a boost. can anyone suggest any specific grounds that it can be? i had my alternator checked, new battery...what does this leave??

i have an aftermarket deck but not sub or amp so it cant be what's causing it...

my dash flickers as well...but from what i gather in the forums soooo does everybody else's lol

any ideas as to what to check next?? for now i will be driving with that fear of being stuckk somewhere :S

[slappy96]

Real similar problem I'm having with an 1992 SC 300. For about a month, the car wouldn't start on the first try. Leave the key in the on position for about 10 sec and it would start strong the next try. Initially thought it was the battery, but it didn't act exactly like it. Over the last thirty days, it got worse and worse until I needed a jump. Got a jump start and drove about 5 miles, BAM darkness. No Dash lights, no power steering, no power brakes, no engine. No nothing except vanity lights, seatbelt light and door going "ding, ding" when you open it. Got a new battery from Sears and took it to the car. Yes, you guessed it for the 10,000th time. Wrong polarity. Guy and Sears was a little questionable on the details and I was in too much of a hurry to check. Massive sparks when I tried to connect the terminals and after that my 120A Alternator Fuse was blown. I have no idea if that happened before or after I tried to put the wrong battery in the car.

Long story longer, I cannot get the 120A fuse out of the car to replace it. (Any ideas:)?) I have a new one, but I don't know if that is going to fix the problem. My plan was to replace the alternator if it didn't, but it sounds like that may not be the issue. I'll definately post if my situation gets resolved.

[SKperformance]

You need to replace all the battery wiring as they are corroded.

I may have some time to do it for you as it is pretty cheap to make the wiring and ends and fit it together.