Break Lights do not work when lights are on

Hopefully one of you have a great answer…

Yesterday while backing up into my driveway I noticed my break lights did not get brighter when I pressed the peddle.

Today I decided to check it out, I have my third break light that works perfectly. My brake lights work when my lights are not on.

Things I checked. Fuses both in cab and hood 10A both look good. Removed the taillight assembly, found a loose wire and reconnected it. Checked all LEDs and they seem to work fine. Put back together and checked again. Third break light works with/without lights on. Main break lights work when lights are off. Turn lights on and no difference between running and breaking.

Could it be the brake switch?

 

I think you can rule out the switch since the brake lights work with the lights off and the 3rd brake light works all of the time.

 

Are you sure the brake lights don’t work when the lights are on?
Or are they actually working and ON all the time with the lights On?

The ground wires should be good. As it grounds both the tail and brake lights.

Do you have trailer towing harness?
Is it damaged in any way?

 

Was the loose wire white/black? That's the ground wire. It's possible it's not really connected. If the ground wire is not connected, weird things happen.

 

I’d probably start with a DVOM and see when I do and don’t have power.
I do agree, grounds do strange things. Seems odd the tail lights work perfect?
Wiggle test the ground wires I guess?

Humm....

 

A Honda Ridgeline and a Toyota Tacoma are trying to get to grandmas house for thanksgiving. Everythings fine as long as the roads good. They can both make it to grandmas house. But, they get to a point where the roads washed out, so they decide to go off road. The Ridgeline is in the lead. They get to a muddy hill that the Ridgeline can’t climb, so the Tacoma pushes him up the hill, and into the ditch so he can drive around. The Tacoma makes it to grandmas house for thanksgiving dinner. The Ridgeline owner gets eaten by bears. The end.

The moral of the story. Share the road until there is no road. Then get the hell out of my way.

OK, not an exact analogy, but close.

 

So what you’re saying is, don’t buy a Ridgeline and take the path of least resistance?
And is there cake at grandma’s house?

 

Bingo!

Grandma always has cake and cookies. That’s what grandmas do.

 

Did you only do a visual inspection? Fuses can look ok but still be blown. Get a multimeter and ohm them out to be sure, or just replace them with fuses you know are good.

 

Power to both brake lights and the third brake light all come from the same place.

Tail Fuse > Stop Light Switch or Stop LP Cntrl Relay (VSC) > Junction Block > Stop Lamps (3) > Ground

The only thing that is different between the Main stop lights and the 3rd stop light is the wiring where they go separate ways from the junction block and the grounds.

I have yet to find a link between the tail lights and the brake lights...

 

Oh, and it's Brake...

My pet peeve is seeing break instead of the proper brake.

 

Green wire was loose. I’ll check all wires to ensure they are tight. Towing harness could be the culprit, it was updated prior to swapping out the tail lights.

My meter battery was dead, so today I’ll replace fuses and check all connections.

sorry for break not brake

I was wondering what if the brake lights are always on with my lights, and I have no running tail lights.

 

If you had a green wire loose then that is for the Tail Lights and not the brake lights.

 

Walk us through your rear light modifications. You installed a towing harness, and everything worked fine. Then you "updated" your towing harness, and now have issues.

You also said you swapped out your tail lights? Are you talking about just replacing the bulbs, or did you change the tail light assemblies? If it was just the bulbs, did you replace them with what's listed in the owner's manual, or did you install LED replacement bulbs? If it was the tail light housings, could the ones you installed be faulty, or have bad electrical connections?

If everything worked fine before, it's has to be one of two things: (1) the towing harness, or (2) the rear brake light housings or bulbs.

My first step would be to disconnect the towing harness, assuming it's a "plug & play" harness, and not something that was spliced into your truck's wiring. If everything works then, buy a new towing harness.

Good luck running this down!

 

Have you looked at the LEDs?

Typically, the taillight bulbs will be a dual filament bulb. One filament is used for turn signals and brake light. The other filament is used for running lights.

Many times LEDs don't have the capability to separate the two.

I think your wiring is ok. The problem happens when the headlights and running lights are on. Check to see if the LEDs have both running light and signal circuits.

 

If you added an aftermarket trailer harness and it has one of those sealed black boxes that convert from amber turn signal logic to combined red turn / brake logic, go no further. Those bad boys crap out all the time and cause all sorts of weird problems. If you have that setup, remove it and tell us what happens.

 

So such a fun day. Fuses replaced, brake switch replaced, tow harness unhooked. Fuses blown, replaced. Now I have brake lights no running lights, test fuses, replace, back to no brake lights. Pull tail lights, pull wires for brake and running lights, swap positions in switch. Now everything works. So when putting in after market please have someone check all functions. I’ve been driving around like this for almost a year.
Now question, since I unplugged my tow hitch, who sells the plug with the harness that is good?
Thank you all!!

 

Try this:

https://www.tacomaworld.com/threads/7-pin-trailer-harness-plug-replacement-tip.288024/

 

Thank you!!

 

It sounds like you have it fixed, Good job.

But what was the specific problem?