3rd brake light voltage - high mount

[jodogg]

Forgive me if this has been hashed out before, but I have been through the threads for the 3rd braks light replacement and diagnosticvs and see some abandoning the ballast system for a "12 volt" LED conversion.

(I have a 96 XLT Explorer 5.0L)

I pulled the harness off the balast and measured 26 VAC at the plug when the brake is pressed. So what am I missing here? Is there some sort of bridge recitfier that takes this back down to 12 VDC? This is what I haven't seen discussed.

Thanks,
Joe

 

[budwich]

not sure what you are saying / seeing. Please give more details as to what you measured, where and how... ie. is that the input measurement, output measurement????

There is NO AC going to the ballast (ie. input), its only uses the 12v DC system... hence my questions. Next, what exactly are you trying to do?... convert the system to leds?, fix a problem? both?

 

[bobflood]

Forgive me if this has been hashed out before, but I have been through the threads for the 3rd braks light replacement and diagnosticvs and see some abandoning the ballast system for a "12 volt" LED conversion.

(I have a 96 XLT Explorer 5.0L)

I pulled the harness off the balast and measured 26 VAC at the plug when the brake is pressed. So what am I missing here? Is there some sort of bridge recitfier that takes this back down to 12 VDC? This is what I haven't seen discussed.

Thanks,
Joe

You have a measuring issue, I believe - there is no real "AC" voltage anywhere on this circuit. Input into the ballast is 12V DC when you push on the brake pedal; output from the ballast is a "much higher" voltage (don't know actual voltage level - sorry) to light the florescent tube.

When mine died, I bought a ballast/light here. Turns out my ballast was bad, so I didn't have to replace the bulb, which is a PITA. When/if bulb dies, I will probably convert to LED - I found a place to buy a replacement LED assembly but by then I already had used ballast/light coming in mail. Good luck.

 

[2TimingTom]

The LED conversion is easy. See my registry for my conversion.

 

[drbenz]

From what I could figure out on my 97 the ballast has 12v dc in and who knows what ac output. My problem was the ballast and it seems like a fairly common issue.

 

[2TimingTom]

Just take the ballast out of the equation and convert it to LED.