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Brake Lights won't work


Rob123

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I have a 2003 Cadillac Seville, and I need some help with an electrical problem. I took it to the dealership to get it fixed and nobody could find the problem.

My brake lights will not light up when I apply the brakes. The "strip" along the trunk lights up, but not the brakes. The lights will light up when I am have them turned on, but nothing happens when I apply the brakes. I know the problem is electrical because when I am driving a warning comes up on my dash to service electrical problem, and my traction control light will light up as well.

These do not happen until I put the car in gear. As long as I am in park, everything works well. It is when I switch to drive

is when the "service electrical system" lights up as well as the traction message.

Someone told me it might be my backup emergency switch, does this make sense to anybody out there.

I live in Pennsylvania, and need to brake lights to work to pass inspection, please can someone help????

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My first thought is the PRNDL switch...

Correct me if I am wrong...your brake lights work when it is in park...

There are no messages when you are in Park...

You put it in Drive ... the messages come up and then the brake lights then DO NOT WORK...

Is this correct ??

One more question... do the turn signals work???

Are you SURE.. did you actually SEE THEM blinking or are you assuming they are because the light on the dash blinks??

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The brake lights will not work at any time when the pedal is depressed. The traction and electrical system only malfunction once I put the car in gear. If I am in park, the traction light will only engage when I actually press the traction button.

Once I put the car in drive, it will stay on all the time

The turn signals work as they should

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Just to eliminate the bulbs as a possible cause, purchase two #3157 wedge type bulbs and replace the bulbs in your fender mounted lamps.

You will have to remove the trim/carpeting to access the wing nuts that fasten the lamp assembly to the body. While you are in there, check the chassis wire harness for damage or evidence of "pinching".

Has there been any recent rear end collision damage repair?

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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What about the codes? The codes will certainly tell why you are getting the "Service Electrical System" message, and they will likely tell whether the PRNDL switch or one of the brake switches needs looking at.

If the 2003 model year won't let you read the codes using the A/C buttons, look at your dealer invoice; if they don't list the codes, ask the dealer, and ask that they always put the codes on the invoice, particularly codes that still appear after work is done, on the invoice whenever they work on your car.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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The OP is a bit confusing, but so is the issue.

Just as JimD said, replace the bulbs or make sure there is 12V in sockets when someone depresses the brakes. Because your strip works properly, I would exclude brake switch as a culprit. With malfunctioning brake switch you would not be able to shift out of park either.

The saddest thing in life is wasted talent

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What about the codes? The codes will certainly tell why you are getting the "Service Electrical System" message, and they will likely tell whether the PRNDL switch or one of the brake switches needs looking at.

If the 2003 model year won't let you read the codes using the A/C buttons, look at your dealer invoice; if they don't list the codes, ask the dealer, and ask that they always put the codes on the invoice, particularly codes that still appear after work is done, on the invoice whenever they work on your car.

I thought there was only one brake switch by the pedal. Where are the others?

The saddest thing in life is wasted talent

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2 that I know of, one for the brake lights, and one for the TCC and cruise.

I would definately be curius of a prior collision, possible chaffed wiring, Defective or incorrect bulb.

Ask yourself this. When did it start and what was touched, if anything before the problem started occuring

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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It just happened one day. I was driving down the street and the Trac Control Light went on. A few days later a man mentioned to me that the brake lights were not going on. I had not noticed this as I was driving, but figured that the two incidents were related. I did change the brake light switch, but that did no good, replaced the bulbs, everything, I just can not get the brake lights to work, only the strip across the trunk.

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If you are getting a DIC message "Service electrical system" then the OBD system is throwing a code that will tell you why.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Maybe this will help some. . .

2003-SEVILLE_BRAKE_LIGHT.gif

Regards,

Warren

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There is no means of avoiding the final collapse of a boom brought about by credit expansion. The alternative is only whether the crisis should come sooner as the result of a voluntary abandonment of further credit expansion, or later as a final and total catastrophe of the currency system involved. - Ludwig von Mises

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If the schematic applies to your car, if the turn signals work then the ground is good. If the CHMSL lights up then the power to the stop lights is good. This schematic shows a stop lamp circuit that does not include the turn signals, implying that the turn signals are separate bulbs. Likewise, I don't see the hazard warning switch in this circuit. This gets us very quickly to the socket wires and the bulbs.

In my model year, 1997, the stop and turn signals use the same bulbs and circuit. If the CHMSL works and the stop lights don't, and the bulbs are good, then the things to look at are the hazard warning switch and the turn signal switches.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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If the schematic applies to your car . . . .

Sorry for the confusion. I edited the drawing to make it plain it is for an '03 Seville. Shouldn't post when I'm tired, I suppose.

Posted Image

There is no means of avoiding the final collapse of a boom brought about by credit expansion. The alternative is only whether the crisis should come sooner as the result of a voluntary abandonment of further credit expansion, or later as a final and total catastrophe of the currency system involved. - Ludwig von Mises

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