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66-96 Ford Broncos - Early & Full Size
jsomedaysoon

both brake lights stopped working at the same time

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i went to get my truck inspected the other day and among other things they found that i had no brake lights. i had checked everything a week ago and it was all working fine. does anyone have any idea why both brake lights would just stop working? i'm not sure if its related but now the brake pedal feels weird too. like i have to stand on it to get the truck to stop and its kinda slugish to return also...

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did you check the switch on the brake peddle lever,maybe a bad or a loose wire there.

the wiring harness should travel on the drivers side back to the left tail lite and then to the right tail lite,if you have a break in a wire at the left side tail lite it will effect both of them,there is also a ground wire to check back there to mounted on the body.hope this helps

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yo!

 

Good stuff Chase!

 

What year is it J?

onethAng that strike me is the loss of lights and the hard pedal @ same time, so ck pedal linkage because a pal once said that his brother slammed on the brakes hard enough to bend the pedal & the switch mount, it caused the lights to shut down, So something may be bent causing these 2 conditions

 

Here is a diagram by our buddy, Fred.

Brake, Turn, Running & Hazard Light Wiring Diagram in an 86

Source: by Seabronc (Rosie, Fred W) at Ford Bronco Zone Forums http://broncozone.com/uploads/monthly_09_2008/post-889-1221442135_thumb.jpg

 

Were brake rotors/pads replaced recently?

 

low or no vacuum to the power brake booster = usually gives a hard pedal; so check that vac line to da booster. If it looks ok, pull it off and feel for vac w/eng running. The hoses are like the rubber hoses at each wheel, they can be damaged internally. So ck them too if brake booster vac is ok.

other poss;

seized caliper pistons, and/ or slides

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awesome stuff. i should've mentioned its an 82. i was kinda leaning awayfrom wiring because the bulbs work as tail lights when the headlights are on so there is power getting to them. but now that i think about it its probably a different wire going into it for the brakes so i'll check out that diagram and see. as for the vac lines going to the brake booster thats a very good possibility considering the condition of other vac lines in the truck i'll check that one out too. i know i didnt stand on the pedal hard enough to bend anything and nothing brake related has been changed recently, thats one of the things that kinda had me puzzled. but i'll check a few of these suggestions out and get back with ya'll.

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yo J..

ok, try this diagram

Brake, Head Light, Turn, Tail, Hazard & Ignition Wiring Diagram in 84 Bronco & F-Series; "...Similar to 80-91 Bronco & F-Series..."

Source: by Steve83 (Steve, That dirty old truck) at SuperMotors.net

http://www.supermotors.net/clubs/superford/registry/media/714912_1

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i finally got time to work on the truck and havent solved the problem yet although i do have a few more clues. i was looking at that wiring diagram miesk5 put up there and i noticed that the hazard flasher was connected to the brake stop switch. so i checked to see if i had hazard lights and i don't. i put in a new hazard flasher and a new brake stop switch on the pedal and still have nothing. i cleaned the grounds for both lights and checked to make sure i had the right bulbs. while down there i noticed some fluid leaking back through from the brake booster along the bar that conects to the pedal. i doubt this is related to the lights but may explain my stiff brake pedal. either way i'm still pretty stumped.

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yo J,

I suggest you get, borrow ;or conive a pal that has w/ a Multi Meter and go thru the Ckt. You did all you can with visuals and that good stuff about cleaning da grnds!

As J from Vegas advsed once

"...have a friend stand behind your truck and when you are pressing the brake pedal move the turn signal arm ever so slightly, if the brake like comes on, your switch is shorted out and must be replaced

very common..."

 

 

Testing Wiring with a Multi Meter, General; Opens, Short, Voltage & Voltage Drop, Continuity & Diodes

Source: by freeautomechanic.com @ http://www.freeautomechanic.com/wiringproblems%206.html

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I had a similar problem with the tail lights not turning on when the pedal is pressed, I usually had to kick the harness around to signal my intention to stop. I went to the junkyard on sunday and found the switch and the harness from a 95 Explorer. I unplugged the harness today and found the terminal burnt. After splicing the cables and reattaching the new harness, the brake lights work as they should.

th_IMAG0112.jpg

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yup, i checked all the fuses and they were all good. the hazard flasher is on the back of the fuse block and i couldnt really test that so i just replaced it. anyway the trucks at the shop now so i should know soon what the deal was and i'll get back to ya'll and let ya know.

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so i talked to the mechanic today and he said the brake light issue was due to a wire problem in the back of the fuse block. i doubt i would've ever found that. anyway its something to check for someone else having this issue.

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Ok so the stop lamps on both sides of my bronco keep going out as well. but it keeps blowing my fuse... I pulled the lights off the back to check to see if i had a break in the wire but no such luck... any suggestions... Oh and it is a 1986 bonco ii...

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Ok so the stop lamps on both sides of my bronco keep going out as well. but it keeps blowing my fuse... I pulled the lights off the back to check to see if i had a break in the wire but no such luck... any suggestions... Oh and it is a 1986 bonco ii...

yo John,

Here is some info that is same as in Ford EVTM for your 86 Bronco II

 

http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=26855

Fuse panel wiring diagram

Shows Fuse #5...is this the fuse that blows out?

 

post-3816-0-55608500-1412082645_thumb.gif

Brake/Turn, etc.

---------

 

http://www.revbase.com/BBBMotor/TSb/DownloadPdf?id=21412

WIRING CHARTS - CIRCUIT NUMBER CODES & COLOR CODES

 

SEE MORE WIRING DIAGRAMS TSBs @ http://www.revbase.com/BBBMotor

 

Best way to find a short is to isolate the entire circuit from Panel to brake light connector and socket;

disconnect connector(s) along path from flasher, multi function switch (MFS, aka turn signal stalk),

 

SHORT CIRCUITS

 

 

 

Never use a self-powered test light to perform checks for opens or shorts when power is applied to the electrical system under test. The 12 volt vehicle power will quickly burn out the light bulb in the test light.

 

1. Isolate the circuit from power and ground.

 

 

2. Connect the self-powered test light or ohmmeter ground clip to a good ground and probe any easy-to-reach test point in the circuit.

 

 

3. If the light comes on or there is continuity, there is a short somewhere in the circuit.

 

 

4. To isolate the short, probe a test point at either end of the isolated circuit (the light should be on or the meter should indicate continuity).

 

 

5. Leave the test light probe engaged and sequentially open connectors or switches, remove parts, etc. until the light goes out or continuity is broken.

 

 

6. When the light goes out, the short is between the last two circuit components which were opened.

 

Our 96's right brake/stop/signal tail lt. assy's wiring harness was chaffing along the passenger side fender panel's sharp edge - where it enters the assy; take a look

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yo John,

OK, got you confused w. jsome on model year;

See SHORT CIRCUITS testing above

Isolate Speed Control ckt if equipped

 

ck from Fuse 1 to brake/tuen/haz lights R/Y wires

 

and as much of the Fuse 1 power in (from Ignition Switch Yellow (Y) wire CKT 37) ckts as possible; may need to pull ign switch

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