Left / Driver's side Tail light Issue - comes on dimly by itself


PL510*Jeff

Well-known member
Mark IV Lifetime
Le Mans 2010 Supporter
Nov 3, 2005
4,876
Renton, Washington
I think the original poster said he has already replaced the battery and checked the ground. However, he didn't say if he had brushed it around the cable ring to remove paint to get a good ground.

I really don't think it is the SJB causing his problem but I guess we'll see.

Yes the SJB may be the issue as everything seems to go through it. While my light problem is "gone" for now, it would be good to know what the root cause may be. Nothing in my automotive experience can explain a light turning on when the car is parked and unattended. Sticky switch? Circuit jumping? Moisture/corrosion? A physical reason that is so far undiscovered and thus my hope is to find an explainable solution.
 

twobjshelbys

GT Owner
Jul 26, 2010
6,053
Las Vegas, NV
Yes, i ground down the paint around the cable ring, and even added another ground wire to the battery. New oddessy battery in place with proper voltage output.

So have you tried pulling the other fuses/relays to see if any other one is related? Note there is a fuse box in the trunk area too.

Also, you said you pulled the fuse/relay, but did you try swapping it with one of the same size?
 
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Xcentric

GT Owner
Mark II Lifetime
Jul 9, 2012
5,213
Myakka City, Florida
Trailers with LED taillights sometimes have this problem. The solution there is to add a load resistor. You might try it. Way cheaper than a new SJB. The SJB may not be returnable once the package is opened.

Did you test how much current the LEDs are drawing? Probably miniscule.

https://www.amazon.com/Resistors-Signal-License-Warning-Cancellor/dp/B004EDF8HY
 
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Johntpr

GT Owner
Mark II Lifetime
Jan 18, 2017
235
Rockland County, NY
Just to update everyone, the new Smart Junction Box arrived and has been installed. Quite an unpleasant job while lying upside down under the passenger side dash !

Anyway, Success ! My tail light finally went off. Wish I knew what really failed inside the smart junction box. Maybe someday, someone can repair them.
 

FENZO

GT Owner
Mark II Lifetime
Jul 7, 2008
1,518
Lafayette, CO
Great news!
 

Johntpr

GT Owner
Mark II Lifetime
Jan 18, 2017
235
Rockland County, NY
Particular thanks to you Fenzo for all your help, and to Rich Brooks from the GT Guys for walking me through many of my questions !
 

PL510*Jeff

Well-known member
Mark IV Lifetime
Le Mans 2010 Supporter
Nov 3, 2005
4,876
Renton, Washington
Great news!

Yes it is. Lingering in my mind is why the taillight turned on.
 

NorthwoodGT

GT Owner
Jun 12, 2009
1,215
Michigan
wow that's good to know. and yes, getting the smart junction box in and out is a real pleasure. I was going to tell you to save the relays out of the old one but there again, maybe you shouldn't. I currently am getting a clicking noise in my junction box when the A/C is on. only the A/C is generating the noise. there again, a relay going bad?
 

Johntpr

GT Owner
Mark II Lifetime
Jan 18, 2017
235
Rockland County, NY
wow that's good to know. and yes, getting the smart junction box in and out is a real pleasure. I was going to tell you to save the relays out of the old one but there again, maybe you shouldn't. I currently am getting a clicking noise in my junction box when the A/C is on. only the A/C is generating the noise. there again, a relay going bad?

You sure it's not coming from the relay box box under the hood? That's where the A/C relay is. Is the A/C blowing cold? Maybe a low borderline charge keeps the relay trying on and off to engage the compressor clutch.

Yes, I will save my old smart junction box. Hopefully, in the future, they can be repaired. The new SJB comes with 2 new keychain remotes. They are matched to the new SJB.
 

NorthwoodGT

GT Owner
Jun 12, 2009
1,215
Michigan
You sure it's not coming from the relay box box under the hood? That's where the A/C relay is. Is the A/C blowing cold? Maybe a low borderline charge keeps the relay trying on and off to engage the compressor clutch.

Yes, I will save my old smart junction box. Hopefully, in the future, they can be repaired. The new SJB comes with 2 new keychain remotes. They are matched to the new SJB.

you are correct. the key fobs supplied have to be used with the matching smart junction box. been there, done that. no, the clicking noise is coming from the smart junction box. has to be a relay going bad. everything works fine including the A/C blows cold.
 

twobjshelbys

GT Owner
Jul 26, 2010
6,053
Las Vegas, NV
Wow, who woulda thunk :)