Right rear brake light not working.... I'm stumped

[Peebody85]

My truck is a 2010 Explorer Sport Trac Adrenalin

I've tried diagnosing this for quite some time but have not been able to figure out the issue.

I used to get the "Check RR lamp" message on the dash once in a while and the brake light would sometimes not come on. Over time it has stopped working completely. The "Check RR lamp" light still comes on periodically. Driving down the interstate, in town, hitting brakes and using turn signals do not trigger it. It's just random.

The driver side brake light/turn signal/ hazard bulb works 100% fine. The running lights work 100% fine on both sides. Front turn signals work fine on both sides. Reverse lights on both sides work fine. License plate lights both work fine.

The turn signals do not flash quickly like when you have a bad bulb, just normal flashing speed.

Here are the things I've done to try and figure out what the issue is:
Replaced brake light bulb
Swapped bulbs side to side
Checked bulb socket
Checked fuses
Replaced multifunction switch


Downloaded the wiring diagrams to help figure this out and thought I could pinpoint the issue. I've not been able to locate the ground connections to rule them out, but according to the wiring diagrams both sides use the same ground so that would not be the cause of the problem.

I'm coming to think it could be the smart junction box, sensor somewhere, broken diode, something like that.

Has anyone had this issue?

I've tried searching but nobody seems to have the same issue that I have. Everything pointed to the multifunction switch but that did nothing and I returned it.

Any help would be greatly appreciated.

Thanks in advance.

 

[mgmgmg]

Peebody85 Keep me updated please. Im seeing a pattern with 2010's only? with this issue? Im sure you read my post on Rear bulb issue. Not the same but im sure there connected.....

 

[Peebody85]

Peebody85 Keep me updated please. Im seeing a pattern with 2010's only? with this issue? Im sure you read my post on Rear bulb issue. Not the same but im sure there connected.....

Thanks MG.

I did see your post. I didnt mention that I've already cleaned the socket, took out the prongs and made sure they were snug in the connector. Just looked for anything out of the ordinary and all looks good. Just tired of having my tail light out with not even a way to fix the issue.

 

[Peebody85]

I've even put LED bulbs with resistors in and the LED bulbs do the same thing so I swapped back to the originals too.

 

[Bill MacLeod]

I don't have the 2010 Sports Trac wiring diagram, but my 2006 Explorer wiring diagram tells me that the 3 bulbs in the tail lamp all share the same ground. But all 3 bulbs have their own ground wire and they merge at a splice. And of course the power supply is the same. ( 3 wires merge at a common splice ) Check the wiring for corrosion at the suspect bulb from the socket back to the splice(s)

 

[Peebody85]

Thanks Bill. My diagram shows the same. I haven't done that yet. I will try to do that tomorrow and see what I can find out