Brake and hazard lights not working

HAIRYJERRY

MEMBER
1995 CHEVROLET SILVERADO
260,000 MILES

I just bought vehicle so know nothing about history or causes.
No brake lights. Also hazard lights do not work. Relevant fuse was blown. Replaced fuse and problem still present in both brakes lights and hazard lights. Fuse did not blow again.
Checked bulbs by swapping positions between brake light bulbs and turn signal bulbs - they tested good. Tested for power at wiring connection at tail light assembly. Running lights (from headlight switch) and turn signal lights have power but brakes no power.

Turn signals work, except when flashers are turned on turn signal stops flashing (does not light). Taillights work. Replaced brake switch - old switch probably good as I could hear the relay click when key was turned on - determined that it is probably the relay for getting transmission out of park. When key is off I do not hear a relay click. Replaced brake relay at fuse box.
Still no brake lights.
Checked bulbs, replaced blown "stop/haz" 30 amp fuse, replaced brake switch, and replaced brake relay inside fuse panel.
Ideas? Thanks, Jerry

4 Replies

KASEKENNY

MECHANIC
18,907 POSTS

I suspect the turn/hazard switch is shorted which is why the fuses are blowing and the lights are not working.

Take a look at this wiring diagram. If you have not power at the bulb, I would jump back to the switch and test power coming out. If none, you can test the power coming in but I am sure you will have it there. If so, replace the switch.

Let us know if we are misunderstanding the issue but that is what would make sense on this one. Thanks

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Saturday, September 19th, 2020 AT 6:47 PM

JACOBANDNICKOLAS

MECHANIC
109,747 POSTS

Hi,

There are two fuses that can cause issues. (See the attached pic) If both fuses are good, confirm there is power to the fuse and out.

There is a splice in the hazard/brake light wiring. If there is power out from the fuse, check at the switch to confirm there is power to the orange wire. If there is, press the brakes and see if there is power out.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Do this and let me know what you find.

Joe

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Saturday, September 19th, 2020 AT 6:48 PM

HAIRYJERRY

MEMBER
2 POSTS

Thanks for your quick response. I was working off of a few false assumptions - one being that I had power to the switch. I thought I had power because when I installed the new switch I could hear a relay clicking every time the switch was engaged - but only when the key was on. Turns out it was related to being able to get the gear shift our of park.
I have no power to the switch. I have replaced the tripped/blown 30amp fuse - it did not blow again - and still no power to the switch. I replaced the brake light relay and still no power. I found what I think is the I/P fuse "box", but there are no fuses in it. There is a Hazard relay that I replaced - did determine that there is no power to any of the terminals for the relay. Noticed a bunch of after market alterations under the dash. Loose wires that went through the firewall and then literally went nowhere. Not sure what is going on with this I/P fuse box.
I assume (here I go again!) That the main problem has to have originated with the wiring associated with the blown 30 amp fuse. The wires all look fine that are coming out of the wiring harness under the dash all the way to the brake light switch. The problem must be closer to the fuse panel. It is so daunting trying to find any particular wire in that mess of wiring harness that I bypassed everything. I hooked a wire to the "Auxiliary A" post at the fuse panel - with a corresponding 30amp fuse - passed it through the fire wall and spliced it into the cut orange wire. Behold! I have brake lights.
I have not run the truck that way - wanted to see if you thought this was an okay fix. I just did it to see if it would give me lights. Now I plan to reconnect it more permanently
from that auxiliary post and to also pull the fuse from the original brake fuse location.
Thanks, Jerry

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Monday, September 21st, 2020 AT 10:32 PM

JACOBANDNICKOLAS

MECHANIC
109,747 POSTS

Hi,

First, that was an excellent way to test if power was the problem. I looked at the schematic again and noted that there only appears to be one power wire to the switch, so you should be fine. Also, since that fuse only seems to power the switch, you should remove it. If it blew once, chances are it will again.

As far as the replacement, just make sure nothing can short or easily become damaged. Also, make sure the wire you used is of a heavy enough gauge to handle a 30 amp fuse. You don't want anything too light which will melt down before the fuse blows. Since the wire needs to be approximately 5 feet, I would recommend no lighter than an 8 gauge wire. That is the norm for up to approximately 15' length at 30 amps. I would be happier if you used a heavier 6 gauge, but that's your call.

The red wire from the fuse must have a break in it at some point. If you were to remove the fuse and check continuity, I suspect you would find there is an issue.

As far as the IP fuse box, it should be under the dash on the driver's side.

Let me know if you have other questions.

Take care,
Joe

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Tuesday, September 22nd, 2020 AT 6:07 PM