3rd Brake Light

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Jul 23, 2017 | 08:27 PM

air1jpg

Thread Starter

Tuned

Joined: Aug 2007

Posts: 492

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From: Louisville

3rd Brake Light

Looking for recommendations on a good replacement LED 3rd brake light that will not leak and includes bed lights.

Jul 23, 2017 | 09:11 PM

Vanquish Auto

Former Vendor

Joined: May 2017

Posts: 208

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Is the current one leaking? I would suggest some butyl sealant around the lamp to create a gasket to stop the leak and upgrade to good led bulbs and keep the nicer factory look. Good luck with your end choice.

Jul 24, 2017 | 11:45 AM

projectSHO89

Hotshot

Joined: Jan 2004

Posts: 19,760

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From: St Louis

If you install an LED 3rd brake light, you usually loose your cruise control.

Jul 24, 2017 | 12:39 PM

alloro

Fleet Owner

Joined: Apr 2008

Posts: 24,316

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From: 0,0,1

Quote:

Originally Posted by projectSHO89

If you install an LED 3rd brake light, you usually loose your cruise control.

Okay you've got my attention, how is that possible? The CC deactivation and brakes lights are two different circuits and the CC deactivation switch is a separate switch from the brake switch.

Jul 24, 2017 | 01:05 PM

projectSHO89

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Joined: Jan 2004

Posts: 19,760

Likes: 1,079

From: St Louis

The logic level of the BPP switch's signalling output is "pulled down" by the 3rd brake lamp (filament low resistance) to a logic "low" at the input to the PCM. Because the typical LED presents as an open circuit when not actively turned on, the BPP's logical input to the PCM is effectively floating and is interpreted as a logic "high" which, to the PCM, indicates the brake pedal is being pushed. Same thing happens if the bulb is burned out.

Previous discussions:

https://www.ford-trucks.com/forums/1...-heads-up.html
https://www.ford-trucks.com/forums/1...e-control.html

Jul 24, 2017 | 02:04 PM

Beechkid

Moderator

Joined: Aug 2002

Posts: 6,099

Likes: 380

From: Southern California

To address the leak........here is what I did on my 2006.....

Purchased a replacement gasket (for mine the design was revised), then IIRR I applied silicone sealant to the lens side of the gasket, applied a light tough of white lithium grease to the cab surface side of the gasket and assembled...not a drop since.