Brake lights stay on?

Bullet3600 · #1 (**permalink**) 11-14-2004, 06:08 PM

I'm am having a problem with my 95 Cherokee Sport. The brake lights will stay on when you turn the lights on. Step on the brake during the day the dash lights come on. I hate electrical, I have checked the brake switch on the pedal and that is ok. Could this possibly be the light switch itself in the dash?

bchcky · #2 (**permalink**) 11-15-2004, 02:30 AM

maybe you put too much blinker fluid in and it overflowed into the brake reservoir?

Bullet3600 · #3 (**permalink**) 11-15-2004, 08:46 AM

You should be replacing Jerry Seinfeld.......NOT

graewulf · #4 (**permalink**) 11-15-2004, 09:23 AM

Quote:

Originally Posted by Bullet3600

I'm am having a problem with my 95 Cherokee Sport. The brake lights will stay on when you turn the lights on. Step on the brake during the day the dash lights come on. I hate electrical, I have checked the brake switch on the pedal and that is ok. Could this possibly be the light switch itself in the dash?

Sounds like the brakes are shorted to the parking light circuit. The switch probably isn't it since the brakes don't run through there. Make sure you have the correct bulbs in the brake assembly. If the bulb is a brake/tail in one bulb, using the wrong bulb could have the circuits crossed. Also check the sockets for corrosion/shorted wires.

Bullet3600 · #5 (**permalink**) 11-16-2004, 12:27 AM

The bulbs are fine it's not those, I have checked the harness out no corrossion but sprayed W-2 40 in it just to keep moisture out but still has the same problem. AAARRRGGGHHH

bchcky · #6 (**permalink**) 11-16-2004, 03:23 PM

Quote:

Originally Posted by Bullet3600

You should be replacing Jerry Seinfeld.......NOT

heh, sorry i was just kidding about my post, i should have told you i'm no help, the blinker fluid thing is just kind of an on going joke here on jeepz. sorry if it made you mad, no harm intended.

graewulf · #7 (**permalink**) 11-17-2004, 06:55 AM

do you have any after-market accessories, radio, etc installed? Some use 2 hot power leads - it is possible to hook to the wrong circuit and introduce a short like this, also make sure that the ground is to the frame/body, not another wire - you may be grounding through the brake circuit.

I've seen where someone only had the problem (very similar) when they turn the radio on and it turns out they grounded to the brake circuit, not a true ground. true story

I had an aftermarket air horn that would go off when I hit the brakes - turns out my ground was off the brake lights (this was on a toyota pickup) which uses a switch on the ground side to activate the lights. When the stock horn was wet and I hit the brakes, the air horn would sound. I was grounding through the tail light bulb wire, which tests as a ground with a meter but is not a true ground.

Bullet3600 · #8 (**permalink**) 11-17-2004, 03:24 PM

Tomorrow I am going to take the rear hatch apart, I think if there is a short it must be in there. I have never touched anything along the floors so it can't be there. The stereo has been installed long before the light problem. Thanks for everyones input, we will see what happens.

XJNick · #9 (**permalink**) 11-17-2004, 06:57 PM

Hi,

My cherokee has three relays behind the driver's side plastic panel in the trunk. These were installed from the factory to power the trailer harness for brake/ tail/ turn signal lights. I'm not sure if all cherokees have these relays in that location, or if they are present if you didn't have the factory tow option... but something to look for. Those relays are the only place I can think of off the top of my head where the brake circuit interacts with the parking lamp circuit, except for the brake lamp holders, of course.

The very first thing I'd do is check for a good ground to BOTH brake/tail lamp holders, though.

-Nick

TwistedCopper · #10 (**permalink**) 11-17-2004, 10:28 PM

The 2 circuits are definately crossed.

My first guess would have been moisture or corrosion in a bulb socket. Since you checked those already...

Is this a problem that started suddenly? have you done any work to it like an aftermarket stereo? How about work on the interior like new carpet, etc?

If you have not done any work in the Jeep and this is a new problem, I would check areas where maybe work had been done, like running of speaker wire, etc. It's possible the wires were displaced into a pinch-point like a door or in the guards along the floor panel and over time they wore down to the point thay they are making contact. Another obvious place to look is behind an aftermarket radio, as somebody may have left wire unisnulated while testing for a good power source or ground.

Note while testing:
The "hot" wire of a lighting circuit will appear as a ground while the switch is off. This is because the hot wire will be open (open switch) at the power source and so you'll read the ground (with the slight resistance of the lamps) at the other end of the circuit.

another note:
WD-40 is conductive. I would not use it so spray harnesses or lighting sockets or anything else that carries voltage. It also has some solvent qualities, which can't be good for them either.

XJNick · #11 (**permalink**) 11-19-2004, 09:51 PM

Hi,

Quote:

Originally Posted by TwistedCopper

WD-40 is conductive. I would not use it so spray harnesses or lighting sockets or anything else that carries voltage. It also has some solvent qualities, which can't be good for them either.

I agree. Intentionally putting any kind of liquid on the wiring harnesses is a bad idea. Instead of trying to displace water, It'd be better to keep ALL liquids off of and out of the harnesses.

-Nick

Bullet3600 · #12 (**permalink**) 11-20-2004, 09:43 AM

Brakes lights are ok now. I took apart the rear hatch and found one of the quick links undone and grounding out. I appreciate the replies and advice. :)