Proper voltage in third light wiring?

[erickperez]

I have replaced my 3rd light with a new led based lamp https://www.amazon.com/gp/product/B07MV8HZTH

I never knew why it stops working as I got the car with the 3rd light not working.

However, after replacing the lamp and when I press the brake pedal, all I see is a faint "blink" of the LEDs and then the lamp stays off.

I found an online site that said the 3rd brake light test fuse #2 20-amps (2005 expy eddie bauer) and also tested for continuity at the 3rd light connector.
all ok.

What will the proper DC voltage be at the end of the wiring? I think my led lights blink and then turn off due to not enough juice.

Thanks,

 

[Hamfisted]

12-13 volts .....

 

[erickperez]

12-13 volts .....

Nowhere near that. When I press the brake pedal I get a faint led flash and my multimeter (dc) shows 0.025

 

[erickperez]

Can someone please confirm that the Fuse is #2?
Also, is the 3rd light wire feed, feeding something else that I can test?
All my tail wiring works ok, it is just the wiring of the 3rd light I am not sure if it's broken somewhere and it goes inside the chassis in a place I cannot reach.

I don't see voltage at all (DC), not sure what else to test (lights on, brake pedal pressed, lights off brake pedal pressed, engine on/ off, etc)

thanks.

 

[Hamfisted]

It's powered by the light green 18ga wire coming directly off the brake pedal switch. Nothing else on that line. It should be fuse #2, but check #5 as well ( hot all the time ) . See if you're getting 12v out at the pedal switch on the light green wire with the brake pedal depressed. I guess it's possible the brake pedal switch could be bad ? How's the the grommet and harness look there in the rear hatch area where it passes into the body ?

 

[erickperez]

No voltage on green line (or the black FWIW)
some pictures to illustrate better.
https://imgur.com/a/jtYlvLn

 

[Hamfisted]

You're getting 12v into the brake pedal switch, but nothing out to the green wire when you depress the pedal ? Bad switch ?

 

[Anthony DeVor]

I know gm used the 3rd brake light to cancel cruise control in the 200-2007 classic trucks I don’t know if ford did anything similar. If you replaced the 3rd brake in the gm with leds cruise would not work because it didn’t sense any power draw


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[erickperez]

This is an old thread but I wanted to update it and provide proper closure. My switch was bad. Replacing the switch solved it.
This is the switch. https://www.ebay.com/itm/Brake-Stop...dition-Lincoln-Navigator-Mark-LT/371411227976