'03 Road King Taillights constantly on?? - Harley Forum

Ranger74 · #1 07-25-2008, 07:21 PM

I've got a 2003 Road King Classic. I noticed my cruise control not working lately and happened to check the brake lights. They are constantly on. I've looked at the rear pedal and front hand break and they don't look loose. Any ideas on wkat else to look for or how I can further troubleshoot. The bulb is fine and correct (two filaments).

evoKENevo · #2 07-25-2008, 08:31 PM

Welcome aboard, Ranger

I don't have the answer to this question..but,I noticed in the other thread you have running here that your wife (still

alive) managed to rear-end your bike the other day..pushing your tail-light bar in an inch or so. Yeah,and,since this COULD have SOME bearing on your question here, I just figured I'd toss in that little tid-bit, for you..to help OTHERS with their replies, in case they had'nt seen your other thread.

Gotta give'em ALL the facts..or,get a PARTIAL answer

buddy.

hotrodsporty · #3 07-25-2008, 09:03 PM

there should not be a wire in that vacinity that would have the 12 volts constant on it to short to the brake light after the incendent, so that should not play into the equation. but some how the brake light is getting power to it and holding out your cruise. I would search the bike for a pinched wire or start with pulling one fuse at a time until you find the light turns off. then trace that wire to find where it is getting voltage. First pull the lamp and check that both filimant conections are getting voltage.

wait..... if by hand the tail light is shorted to the brake light after the accident then there is your culpret.

thanks ken for filling us in on the whole situation

evoKENevo · #4 07-25-2008, 09:48 PM

Here again,I'm just kinda feelin' around in the dark...but, could the same short (if it exists) to the brake light also be killing the cruise-control (mentioned) that kicks-out (electrically) when the brakes are applied ????

Makes sense in my

mind !!

HarleyCruiser · #5 07-25-2008, 09:55 PM

Quote:

Originally Posted by Ranger74

I've got a 2003 Road King Classic. I noticed my cruise control not working lately and happened to check the brake lights. They are constantly on. I've looked at the rear pedal and front hand break and they don't look loose. Any ideas on wkat else to look for or how I can further troubleshoot. The bulb is fine and correct (two filaments).

Yea the brake light is canceling the cruise, try unplugging the rear brake switch, the front you will have to go inside the controls. If you take the front brake handle off and don’t use a spacer it can ruin the brake switch. Get out your schematic and see if you are hot on both sides of the switch.

evoKENevo · #6 07-25-2008, 10:34 PM

OK..now I've got to ASK why you would'nt just find & fix the short (most likely where the damage is) and,hopefully, call it a day?

I mean,is there something else complicating things I and others should be aware of..or,are you just considering an alternate source of the problem ??

Geez..all this "new & improved" stuff just seems to be a big pain in the ass..to this "Ol' Fart"

anyhow !!

Ranger74 · #7 07-26-2008, 02:03 PM

Obviously I'm not a brake specialist..but... understanding how the back brake light works may help me trace the source of the problem. I've had brake lights and a working cruise control after the accident, so I don't think the accident contributed to the problem.

Obviosuly the bulb is getting power, so I would assume the path from the batterry thru the fuse to the light is okay? Does the back light burn both filaments with a lower voltage and then applying the brakes adds more voltage, thus a brighter "brake" light? or does one filament burn constantly as a running light and when brakes are appeared power goes to the 2d filament?

If it's the first, what device in the circuitry separtaes the lower vs higher volatge.

If it's the second, what device sends power to the second filament.

Knowing this will help me trace the voltage.

Thanks for the assist.

milindh · #8 07-26-2008, 02:38 PM

Hey Ranger 74

You have to get a look at the schematic for your bike. It's all, including how your brake light bulbs work, clearly shown in the HD service manual. If you don't have one you should definitely get one.

For what it's worth, I think Harley Cruiser is on the right track here about the brake turning off the cruise control since applying the brakes is supposed to turn off the CC and just because it all worked after the accident doesn't mean that the whole mess didn't start with the accident. A prolonged short in the brake lights might have led to or even caused a later glitch in your cruise control system. I also think EKE is right in that you should fix the known (or at least suspected) short first. An ohmeter and a schematic will take you a long way towards the truth of the matter.

I believe we get ourselves into trouble quickly by throwing a, "It can't be this..." into our investigation without actually physically checking it out. One small wrong assumption can turn the whole compost pile into a stinking mess.

Good Luck Dude

evoKENevo · #9 07-26-2008, 03:43 PM

I'll leave the elec. diagnostics to others here. Because I really HATE elec problems...don't keep all that stuff in my head...and,usually have to refer to my shop manual when I do have that kind of problem. But, like milindh says..don't eliminate the possibility/probability that the problem is related to the accident damage W/O looking into it.

I mean, it could be a whole new/unrelated problem. But, it could also be that a short in the system did'nt develope until wires that were knocked out of place had awhile to rub insulation off before contacting each other either directly OR via the same piece of metal they'd rubbed on...and THEN caused whats happening now. Which is the more LIKELY scenerio IMO anyhow

shovelmike · #10 07-26-2008, 03:55 PM

I agree with what evoKENevo says in the previous post, start tracing it down concentrating on the damaged area.You asked: or does one filament burn constantly as a running light and when brakes are appeared power goes to the 2d filament? Yes, the second filament is used during braking only. Best of luck, work methodically and you will find the source of the problem.