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2004 Chevy Silverado Brake Lights
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cfreeman5343
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Jun 7, 2013, 5:42 PM
Post #1 of 30
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2004 Chevy Silverado Brake Lights
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My brake lights on the bed of my truck don't work when I depress the pedal. The cargo brake light works, but not the two most rear brake lights.
My back-up lights, hazard flashers and blinkers all work on the back. Just not the rear brake lights.
I've checked the fuses - all good, replaced the bulbs.
I read somewhere about a BOO (brake on/off) switch possibly going bad. Anyone know where this might be or if it might be the problem? What else might be the problem?
Thanks for any responses. In the meantime I'm going to replace the brake light switch under the brake pedal. I'll let you know if that works.
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Discretesignals
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Jun 7, 2013, 5:48 PM
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Re: 2004 Chevy Silverado Brake Lights
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It won't work because if the brake switch was bad the third brake lamp wouldn't function either.
BOO is a term used by Ford. BOO is one of the inputs for the engine computer on a Ford.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jun 7, 2013, 5:56 PM)
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cfreeman5343
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Jun 7, 2013, 6:17 PM
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Re: 2004 Chevy Silverado Brake Lights
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Yeah, I did some more research on this and found that I shouldn't bother replacing the brake switch. Thanks for the input.
Any other ideas? I've been going over fuses and can't seem to figure out what's wrong.
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Discretesignals
Ultimate Carjunky
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Jun 7, 2013, 6:18 PM
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Re: 2004 Chevy Silverado Brake Lights
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Do the hazards work?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jun 7, 2013, 6:21 PM)
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Hammer Time
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Jun 7, 2013, 6:20 PM
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Re: 2004 Chevy Silverado Brake Lights
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You most likely have a bad combination switch. The 2 lower lights pass through the switch so the turn signals can cancel the brake lights.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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cfreeman5343
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Jun 7, 2013, 6:20 PM
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Re: 2004 Chevy Silverado Brake Lights
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Ok, I don't own one of those. Figure it's something I should own, so I'll go get one. What does it tell me about the problem if I get a positive result? What about a negative?
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cfreeman5343
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Jun 7, 2013, 6:21 PM
Post #7 of 30
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Re: 2004 Chevy Silverado Brake Lights
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Well it's not just when the turn signal is on. The brake lights don't work any of the time.
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cfreeman5343
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Jun 7, 2013, 6:22 PM
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Re: 2004 Chevy Silverado Brake Lights
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Yes, hazards work. All the lights are working except for rear two brake lights when pedal is depressed.
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cfreeman5343
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Jun 7, 2013, 6:32 PM
Post #10 of 30
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Re: 2004 Chevy Silverado Brake Lights
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Alrighty...
So do we think this is the problem. I'm pretty confused.
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Discretesignals
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Jun 7, 2013, 6:35 PM
Post #11 of 30
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Re: 2004 Chevy Silverado Brake Lights
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I don't think the stop lamps run through the turn signal switch.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jun 7, 2013, 6:38 PM)
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Hammer Time
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Jun 7, 2013, 6:39 PM
Post #12 of 30
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Re: 2004 Chevy Silverado Brake Lights
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Have you tested fuse #15?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Discretesignals
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Jun 7, 2013, 6:47 PM
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Re: 2004 Chevy Silverado Brake Lights
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If the turn signals in the rear work, you can pretty much conclude you have a good ground, so you are probably missing power to the bulbs. The area you'll be isolating the problem in is between the fuse and bulbs if the fuse checks out.
You can verify with a volt meter or test lamp. Your going to need either one to be able to isolate the problem unless you visually see it.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jun 7, 2013, 6:51 PM)
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cfreeman5343
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Jun 7, 2013, 7:14 PM
Post #14 of 30
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Re: 2004 Chevy Silverado Brake Lights
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One, thanks for the replies. Big help.
Two, went to wal-mart, bought a cheapo test lamp. And a snickers bar.
Test lamp does NOT light up when testing the 15 amp fuse. The fuse doesn't look burnt out. I tried replacing it with a spare fuse, that one doesn't light up the test lamp either.
Test lamp does light up when I test other fuses for functions of the vehicle that are working.
Another trip to wal-mart to get a 15 amp fuse maybe? Or something with the wiring?
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Discretesignals
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Jun 7, 2013, 7:28 PM
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Re: 2004 Chevy Silverado Brake Lights
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You are testing that VEH STOP 15 amp fuse while your pressing the brake pedal right?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jun 7, 2013, 7:28 PM)
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cfreeman5343
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Jun 7, 2013, 7:29 PM
Post #16 of 30
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Re: 2004 Chevy Silverado Brake Lights
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Tried replacing the 15 amp with a fuse I knew was good from testing in another location. At this point I'm gonna guess not getting power to the fuse itself for some reason? So very confused.
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cfreeman5343
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Jun 7, 2013, 7:32 PM
Post #17 of 30
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Re: 2004 Chevy Silverado Brake Lights
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"You are testing that VEH STOP 15 amp fuse while your pressing the brake pedal right?"
...
Ok....I guess that means you can probably laugh at me.
***EDIT***
Testing while pressing brake pedal...fuse lights up the tester. (Can't believe I didn't think of that)
(This post was edited by cfreeman5343 on Jun 7, 2013, 7:35 PM)
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Hammer Time
Ultimate Carjunky
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Jun 8, 2013, 3:08 AM
Post #18 of 30
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Re: 2004 Chevy Silverado Brake Lights
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There is a 25amp STOP LP fuse in the underhood fuse box.
There is also a 15amp VEH STOP fuse that is the likely culprit.
Again, this one is only hot when applying the brake.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Jun 8, 2013, 3:12 AM)
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Discretesignals
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Jun 8, 2013, 7:22 AM
Post #19 of 30
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Re: 2004 Chevy Silverado Brake Lights
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The next place that you could check is at the junction block for the rear lamps.
The location is on the left frame rail near the rear of the vehicle.
Looks like this:
If you look at the wiring diagram above there is a little box (CONN ID) inside the rear junction block that lists the connector colors.
The connector you want to play with is connector C1 which is the blue connector. Don't unplug the connector when making your check. You want to take a small paper clip or even better a sewing pin and back probe the connector at the the light blue wire on pin B. Check for power at that pin while someone holds the brake pedal down.
back probing:
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jun 8, 2013, 7:27 AM)
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Hammer Time
Ultimate Carjunky
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Jun 8, 2013, 7:28 AM
Post #20 of 30
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Re: 2004 Chevy Silverado Brake Lights
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That VEH STOP fuse specifically powers the 2 lower lights only after passing through the other fuse he checked. See your diagram, the LT BLU goes back through the front fuse box.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Discretesignals
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Jun 8, 2013, 7:39 AM
Post #21 of 30
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Re: 2004 Chevy Silverado Brake Lights
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He just check for power at the VEH STOP fuse and stated he had power there when he pressed the brake pedal.
The light blue after the VEH STOP fuse goes back through the underhood fuse box because there is a junction in that block that splits off and sends brake switch power to the PCM and the TAC for inputs.
He don't have a scanner and can't check datastream PID for brake switch input at the PCM, so the next logical and easy place to check would be at the rear junction block for power at the light blue wire.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jun 8, 2013, 7:42 AM)
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Hammer Time
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Jun 8, 2013, 8:01 AM
Post #22 of 30
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Re: 2004 Chevy Silverado Brake Lights
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Yeah, you're right. I was under the impression that fuse was in the underhood box as you see in the diagram, it goes back through the underhood box after that fuse.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Discretesignals
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Jun 8, 2013, 8:07 AM
Post #23 of 30
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Re: 2004 Chevy Silverado Brake Lights
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Here is a more complete diagram in the power distribution schematics:
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Hammer Time
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Jun 8, 2013, 8:19 AM
Post #24 of 30
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Re: 2004 Chevy Silverado Brake Lights
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Do you see what I'm talking about right in the center of the page?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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cfreeman5343
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Jun 8, 2013, 10:44 AM
Post #25 of 30
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Re: 2004 Chevy Silverado Brake Lights
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Thanks for all the replies. I'll be back working on this this afternoon.
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