Brake lights not working. It's not the brake switch. - Ranger-Forums - The Ultimate Ford Ranger Resource

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Brake lights not working. It's not the brake switch.

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Old 04-30-2015
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Brake lights not working. It's not the brake switch.

My brake lights do not work. I have checked every fuse and bulb. I have pulled the switch, took it apart, cleaned it, used a multimeter to check it, triggered it manually, still nothing. I have applied the multimeter to the brake light sockets, not a fraction of a volt when the brakes are pushed. I checked the power going into the break switch, I get 11.5 ish volts. I am pretty certain it is not the switch. I can't find a wiring diagram for the break lights, so I don't know where to test next to pinpoint the problem. I just know it's some where between the switch and the bulbs.

Also, it may be relevant, the light on my towing package no longer comes on when pressing the breaks. A while back, when i had to pull a trailer and the lights weren't working, it was due to a bad ground on those little four pin towing plug thingies (technical term). I only replaced one at the time, and bypassed the six pin and plug instead just plugging it directly into the 4 pin on the trailer. I have since replaced the other side and reconnected the four pin to the six. I don't know if that's relevant.
 
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Old 04-30-2015
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On 2002 wiring diagram the brake pedal switch gets power from Fuse #13 20amp in fuse panel(hot all the time), Light green/red stripe wire.
From other side of switch there is a light green wire that goes out to a Splice, where a Dark Green wire is connected and this wire goes out to upper Cab brake light directly.
Is upper cab brake light working?
If not then either bulb is bad or ground is, because if you do have power at brake pedal switch then no reason that bulb shouldn't light up.

At that splice above the light green wire continues on and goes to the Multi-function switch(turn signal switch).
Multi-function switch sends out rear brake light power(from brake switch) to 2 fuses, #3 and #7 both 7.5amp.
These fuses also feed the trailer connector.
Multi-function switch is used because turn signals and brake lights use the same bulb, so when you are turning and using the brakes the light can still flash, just FYI.

So I would test if you are getting 12volts at fuse #3 or #7 when brake pedal is pressed, if not then power is not passing thru Multi-function switch.

Ford multi-function switches do fail, usually a turn signal issue but brake light power does pass thru there so..........could just be a loose connector.

The wires in question from Multi-switch to the fuses and back to the brakes light bulbs are the same color all the way:
Left side light = Dark Blue/White stripe
Right side light = Brown/Yellow stripe
 

Last edited by RonD; 04-30-2015 at 07:32 PM.
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Old 05-01-2015
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Thankyou so much for the reply, that information is exactly what I was looking for. So the upper cab light is not getting any power when the brakes are pressed; I checked it with the multimeter. So if the switch is good, but the upper cab is still unpowered, this points to a bad ground then? where would the bad ground be?
 
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Old 05-01-2015
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It wouldn't be a Ground if you checked for voltage at upper brake light, assuming your meter had a good ground.

So I would test brake switch again, make sure the Light Green(no stripe) wire has 12volts when brake pedal is depressed.
I use sewing pins to pierce wires to test voltage, doesn't make a big enough hole to effect anything.

If no voltage then unplug brake switch connector and use a jumper wire between the 2 wires, that's what the switch does, it connects those 2 wires together, then see if brake lights come on, if so replace switch.

Tail lights are grounded at the back of the truck and upper brake light is grounded where it screws to the metal cab(I think), but grounded in the cab in any case.

A bad ground could explain why upper bulb doesn't light up, but then tail lights would light up because they don't share a ground, and visa versa.
 
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