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-   -   Third brake light causing the brake lights to stay on? (http://www.ramforumz.com/showthread.php?t=52625)

Due 05-02-2010 12:16 PM

Third brake light causing the brake lights to stay on?
 
Well the other day my wife and I were running errands and had stopped to grab a bite to eat when I noticed my brake lights were on (in the tail lights only, not the third brake light). Before we left I tried hitting the pedal a few times, pulling up on the pedal, started the truck and shifted into all gears but I could not get them to go off at all although the third brake light was coming on and off as normal. On the way home we made one stop and when I checked they were off, so I tested them and they were all working normally. Unfortunately, when I got home they were stuck back on.

At that point I unhooked the battery for approx. 5 minutes to see if that would do anything but they were still on when I reconnected it. Then I started checking fuses and all were good but the only ones that would shut off the lights were the Ignition-Blower Motor (#4) which would shut both off and both FCM Power Feed fuses (#11 & #13) which each would shut off one side. After pulling the FCM Power Feed fuses though, none of the brake lights worked at all until I disconnected the battery. Once reconnected the third brake light would not work at all and the brake lights were still on. I thought maybe it had something to do with my l.e.d. tail lights so I hooked up my old ones but they were doing the same thing so then I thought it was probably the brake light switch and replaced it but the lights were still on except for the third brake light. I wasn't sure what else to check so I checked the third brake light to see if it was burnt out, which it did not appear to be but I went ahead and swapped it for one of the cargo lights. As soon as I did that all my lights started working properly. They have been fine for 2 days now.

Does anyone know why this happened and how swapping the third brake light fixed it?


Thx

erm 05-02-2010 12:21 PM

Wow...never heard of such a thing before.

RamTech 05-03-2010 09:20 AM

Perhaps the bulb was defective somehow and was causing a short. I'm curious to see if this fix lasts.

05atlanticblue 05-19-2010 03:02 AM

well i'm not the only one, mine does the same thing every so often. i get them to shut off by turning the key to the on position and off again.

it's not the brake lights that stay on, it is the running lights in the tails only. while on, they will occasionally flicker, when they do i can hear a relay clicking in the relay box under the hood.

mine did it with the stock taillights as well as led units, so it's something in the electricals.

there have been some other glitchy lighting issues when the key not in the ignition - which get reset by turning the key on and off

RamTech 05-19-2010 11:27 AM

Quote:

Originally Posted by 05atlanticblue (Post 219883)
well i'm not the only one, mine does the same thing every so often. i get them to shut off by turning the key to the on position and off again.

it's not the brake lights that stay on, it is the running lights in the tails only. while on, they will occasionally flicker, when they do i can hear a relay clicking in the relay box under the hood.

mine did it with the stock taillights as well as led units, so it's something in the electricals.

there have been some other glitchy lighting issues when the key not in the ignition - which get reset by turning the key on and off

Given the year of your truck, I'm inclined to think your FCM is on the fritz.

Toms Blue Ram 1500 05-19-2010 01:14 PM

Wow that sounds unusual . Let us know if it's fixed for good in a couple of days .

Due 05-19-2010 01:43 PM

Ya I'm still confused on what the actual problem is, so far mine have been fine since I switched the light out and it has been like 3 weeks.

Not sure if this could be related to the problem or not but a few days ago I noticed I can pull my keys out of the ignition even if it is not in the off position. I ran into the store and when I came back to my truck I heard the stereo playing. When I looked I had not turned the key to the off position but they came out as usual.

Oh and it's probably a dumb question but what exactly is the FCM?

RamTech 05-19-2010 02:33 PM

Your lock cylinder is worn out and FCM is the Front Control Module.


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