2012 Wrangler Third brake light out. - JeepForum.com
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Unread 08-14-2013, 05:35 PM   #1
paul84043
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2012 JK Wrangler 
 
Join Date: Oct 2010
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2012 Wrangler Third brake light out.

Apparently I'm the only person to ever have the center brake light fail.. I've searched and come up empty.
Went in for an oil change today and they tell me my third brake light is out.
I am still covered under warranty, but they didn't have anyone on hand to look at it, so I brought it home and tore into it myself.
I know floating vehicle electrical systems are a PITA, but I put a meter on the brake light connector and get no voltage from either connector to the door latch or across both terminals in the connector... I didn't try to land it anywhere else, I figured the bare metal door latch was a pretty good "ground".
I had this same problem metering a VW fuel pump, so it's probably something I'm doing wrong..
Side brake lights are working fine. Wiring looks fine.
Is there a separate relay for this light? (I seriously doubt it)
No other mods to this area of the Jeep.

I ohm out the LED light itself and get about 450 megohms, which seems high. The reading jumps around a lot though.

Anyone else attempt to troubleshoot this problem?

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Unread 08-14-2013, 08:20 PM   #2
Prot
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Location: Lafayette, LA
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Quote:
Originally Posted by paul84043
Apparently I'm the only person to ever have the center brake light fail.. I've searched and come up empty.
Went in for an oil change today and they tell me my third brake light is out.
I am still covered under warranty, but they didn't have anyone on hand to look at it, so I brought it home and tore into it myself.
I know floating vehicle electrical systems are a PITA, but I put a meter on the brake light connector and get no voltage from either connector to the door latch or across both terminals in the connector... I didn't try to land it anywhere else, I figured the bare metal door latch was a pretty good "ground".
I had this same problem metering a VW fuel pump, so it's probably something I'm doing wrong..
Side brake lights are working fine. Wiring looks fine.
Is there a separate relay for this light? (I seriously doubt it)
No other mods to this area of the Jeep.

I ohm out the LED light itself and get about 450 megohms, which seems high. The reading jumps around a lot though.

Anyone else attempt to troubleshoot this problem?
You do what a diode really does right? It allows electricity to flow in only one direction. Reverse your leads and post your reading.
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Unread 08-14-2013, 09:28 PM   #3
ncb
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Hook meter leads to the two wires have someone press the brake pedal and check for 12 volts. If you have twelve volts then connect the brake light directly to the battery to test it. If it doesn't light up reverse the wires. I can't remember which color wire is + and - on the light. Start simple before ripping it apart.
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Unread 08-15-2013, 06:52 AM   #4
paul84043
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2012 JK Wrangler 
 
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Quote:
Originally Posted by ncb View Post
Hook meter leads to the two wires have someone press the brake pedal and check for 12 volts. If you have twelve volts then connect the brake light directly to the battery to test it. If it doesn't light up reverse the wires. I can't remember which color wire is + and - on the light. Start simple before ripping it apart.
I did this and got nothing, but I don't know how Chrysler does it's electrical. I'll get a longer test lead from work today so I know I'm landing it on a good solid negative to the battery and try again. I had my daughter run the brakes for me and the others were coming on.
I had this same issue on a VW fuel pump where I tested it every way to Sunday and never got a reading, but the new fuel pump worked...?
Freaking vehicle electrical systems...
I didn't reverse the leads on the LED assembly itself. By that time I was hot, sweaty, and seriously wondering if my meter is toast.
It's under warranty still, I just like to dig into things myself if possible. Even if the LED assembly has a blown diode (yes....I know what a diode is) it's a sealed unit and they should still replace it at no cost to me.
It's just frustrating because it should be so simple...yet it never is...
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Unread 08-15-2013, 08:37 AM   #5
ncb
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The Jeep is wired like most other vehicles. Chassis/body is a ground. In the case of the third brake light one wire is -/ground and the other is +12 volts.
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