Brake Light Switch question

waysidecharlie · **Joined:** Sun Nov 16, 2014 11:12 am **Posts:** 46

Brake light switches can be used only once. -- What is the reason for this?

There is also a black lever on them, and the instructions I have seen are not clear. Do the come from a factory with that level at 45 degrees, or 90 degrees.

Instructions say install it them move the lever, but they don't say why it can only be moved once.

My brake lights are on all the time, so I'm assuming its the switch.

GordnadoCRD · **Posted:** Thu Oct 17, 2019 5:45 am

Yes, it probably is.

The switch is constructed that way because of the differences (excessive tolerance) between vehicles, and needs to be set for individual vehicles when installed.
(Yeah, another Mopar idea, but it does work when done right)

Between the electrical switches inside, and the sensory pad touching the pedal, there is a finely serrated rod, (pad side), and a strongly spring-loaded clamp around the rod (switch side) which are kept apart by the lever you refer to and the clip it operates, until installed and in proper arrangement.
When you trip the lever, the clip is freed to clamp tightly around the rod, establishing the proper relation between the pedal arm and the switches inside. (there are actually 2, working in parallel)

I have tried to re-use, by disassembling, and re-assembling a used (but good) one, and re-assembling it in the as-purchased, held-open-lever position, and re-installing it. It worked for almost 2 days, then again slipped into the brake-lights-always-on mode and ran the battery down overnight - again.

another note: The one I took apart was originally acquired from AutoZone. It surprised me that such a chinzy part actually was assembled with grease in the locations where parts in contact slid against each other. The switches were dry, and were not a sliding contact, but a points-type switch. The plastic ramps that operated them had grease.

They aren't expensive, so I now carry an extra one in case the current ones fail, as they will run the battery flat even if the key is out when they fail.

waysidecharlie · **Joined:** Sun Nov 16, 2014 11:12 am **Posts:** 46

Thanks for explaining the design.

Right now I have the switch removed from the circuit, and the brake lights are still on. I think that should eliminate the switch as a the problem. I also disconnected the pos. and Neg battery cables, hooked them together over night, which reportedly does a hard reset of the total integrated power controls, e.g., the fuse, relay panel.

Does anyone have an idea where I should look next?

There are no codes.

GordnadoCRD · **Posted:** Fri Oct 18, 2019 7:44 pm

are both brake lights on, or just one side?

waysidecharlie · **Joined:** Sun Nov 16, 2014 11:12 am **Posts:** 46

Both lights and the third light are on. -- I can't find what is triggering the lights. They were on with the brake light switch removed. I put in a new switch and it did not fix the problem.

The other confusing anomaly is this; I have the factory tow package. When I use a LED trailer wiring plug in tester, everything is normal. But the P3 brake controller reports power loss. That has 4 wires; ground, power, brake switch trigger wire, and one wire to the electric trailer brake. -- on its screen it says no power, which is confusing it comes directly from the battery. Unplugging the controller makes no difference. The brake lights are still on.

I also don't see the tail lights on. Just brake lights. That sort of make me suspicious of the fuse/replay panel. And its a $500 part.

I've ordered a LAUNCH Scanner CRP429 tool. Hopefully it will narrow down the problem.

GordnadoCRD · **Posted:** Sat Oct 19, 2019 10:07 pm

At this point the problem has gone past things with which I am familiar on these.

You know the power is getting to the brake lights from somewhere. It's either getting there VIA the normal brake circuit wiring AFTER the brake switch, or VIA the trailer brake wiring.

To find where it's coming from, I would start pulling fuses / breakers until the guilty contributor is discovered. Check the PDC or panel connector behind the fuse box, whichever applies to what you've found.
If it's not a fuse box circuit, it's got to be a battery +, and probably worn insulation or some such.

Good luck! Let us know what you find.

EDIT- I've no experience with that particular meter but I know a couple of guys who have them and they love them. Say they do a lot for the money, but software updates past the free period are kind of expensive.

waysidecharlie · **Joined:** Sun Nov 16, 2014 11:12 am **Posts:** 46

Follow up -- Posting in case someone else has the experience.

Have not located the source of the problem yet, but have ruled out the brake light switch, since replacing it did not correct the problem. Have also ruled out a defective TIPM. Got one from a junk year and the problem is not corrected. Waiting for a scanner to be delivered to check other things.

There seems to be some connection between the brake lights being on, and running lights being off, and no power to trailer brakes.

Lando-Liberty · **Posted:** Tue Oct 22, 2019 4:39 pm

I hate CAN Bus. Vehicles were much simpler when every item that needed a wire got its very own wire, no computer required.

waysidecharlie · **Joined:** Sun Nov 16, 2014 11:12 am **Posts:** 46

Lando-Liberty wrote:

I hate CAN Bus. Vehicles were much simpler when every item that needed a wire got its very own wire, no computer required.

I have no love for CAN bus either. I think its designed to make you spend money at a dealer. -- In my case, I know there is a connection between the factory tow package and the brake lights/tail lights but nothing shows up on a scanner. All the codes tell me is there is some issue with the brake switch and ABS. Meanwhile there is a new brake switch, and they only install and work one way. And at the same time, there has never been an ABS dash light come on. So the code claimed connection seems pretty sketchy. In other words if there was an ABS issue, CAN bus failed to tell me on the dash.

On top of that, after digging for information I found there are tow harness relays they stuffed under a plastic panel (and this is true of aftermarket harnesses too), that you can only get to after removing the back seat. -- My brake light on problem seemed to start about the same time a trailer LED light had a short in wiring. The harness relays are suppose to isolate the harness and brake/tail lights, and prevent such a problem.

I've also discovered that all the claims about a TIPM (the fuse/relay panel) being not serviceable and requiring dealer programming is nonsense. -- There are companies that rebuild them for $200, and for fun I got one out of wreck that was also a 2012 with a tow package, put it in, did a hard reset it on it and there are no problems. Everything that didn't work before, still doesn't work and everything that did work still does. A dealer would have wanted $1800 for that. Mine cost 80 and a two hour drive.

Just posting this in case it helps someone else, someday.

Billybob · **Posted:** Mon Nov 04, 2019 1:47 pm

I do not know the KK at all..other than when they use the same processes as the KJ does.
Also do not have wiring diagrams for them....need to try find some free ones!

But the later KJs do have an extra switch inside the Brake Fluid Reservoir that works in conjunction with the brake switch contained in the brake switch assembly...maybe that switch...if it exists on the KK...is ON all the time!

That or a Tow Package problem

Also I think it was Squeeto who posted on how to re-use the brake switch assembly on the KJs:wink:

Scar0 · **Posted:** Mon Nov 04, 2019 3:26 pm

waysidecharlie have you tried removing the trailer brake controller trigger wire?

Lando-Liberty · **Posted:** Mon Nov 04, 2019 5:17 pm

I am unclear, did you find the mystery relays in the backseat? If so, what happens if you remove them? I bet if there are multiples of these relays, they are all the same relay. Have you marked them, and then tried moving them around to see if the lights would go out?

Scar0 · **Posted:** Tue Nov 05, 2019 2:57 am

OEM(factory installed) harness relays are supposed to be in the LR quarter panel.

Brake Light Switch question

Who is online