I'm working on a 1986 28 foot P-30. I decided to change out my old purple tail light lens and replace them with LED. I pulled the old tail lights off. I cut the wires off all the brake and tail lights to rewire for the LED lights. When it was time to wire up the new lights I used a volt meter to check which wire was which. When I turn the headlights on all the wires have twelve volts even the brake/turn signal wiring. How do you suppose the voltage is jumping into the brake circut?

Did you bump the turn signal or hazard button?

What does a test bulb show? Sometimes a digital meter will show up a phantom voltage that a test light will not notice.

Bill I turned on the turn signals to check the wiring and then they stopped. I figured I blew a fuse.

Does your vehicle use one of those silver colored small canister type turn signal relays? Those things can really act up if you change the resistance by adding or eliminating bulbs. I have had them click real fast just by hooking up a trailer light. As a test, I would wire up the old lights and see if anything works and go from there.

LED Lights require an LED Flasher. To test, remove the old flasher and insert a jumper wire - if the lights come on steady, then it's a resistance issue that requires the installation of the LED Flasher.

Now, this might also mess with your cruise control. If it does, you'll need to wire up a lightbulb to the brake light switch too.

Here is Ed having a similar issue.



That is the "dummy" load for the brake light circuit, after I replaced the tail/stop lights with LED lights, there is not enough resistance

Now, to answer why all circuits seem to be powered up...

quote:

Originally posted by Dennis:
When I turn the headlights on all the wires have twelve volts even the brake/turn signal wiring.

This sounds to me like you're having a bad ground - all wires sound like even the ground wire is hot. Take your test light and confirm - if the ground is hot, find a better ground.

On a missing ground scenario, the other circuit will become the ground and backfeed the 12v down the line.

Here is Rusty, and I, helping another member with the "same type" of problem. It might be worth the read...

Problem solved. I started checking grounds like everyone suggested and found a bad ground in the passenger side back marker light. I pulled the wiring out of the light and the tail lights work as they should. Thanks again for the help. Barthmobile rocks! Dennis

I'm looking to replace my tail lights and blinkers, where did you purchase your LED tail lights/blinkers?

if you just want to change the bulbs go to superbrightleds.com the bulbs allready have the circuit board in the bulb just order 1057 and 1056 they work well just add a brake light in the circuit before the leds .If you do that you should not have trouble with cruise control . your cruise workes off the voltage drop on the brake light circuit .
lenny

quote:

Originally posted by lenny and judy:
if you just want to change the bulbs... just order 1057 and 1056...

If you do go this route, order up RED BULBS for the red/pink lenses.

quote:

www.superbrightleds.com
Which Color LEDs should I use?

For best results the LED color should be the same as the lens color or if bulb is behind a clear lens, use the appropriate color for turn and brake light functions. As an example: a red lens will filter out all but the red portion of the light so if the light is all red, none or very little light will be blocked by the lens. The light from a White LED contains very little light in the red portion of the visible spectrum so most of the light would be filtered out by a red lens.

Also take a few more minutes to read some of the other notes below this one at that link.

quote:

Originally posted by Bill N.Y.:
www.superbrightleds.com

Also take a few more minutes to read some of the other notes below this one at that link.

In particular:

"LED bulbs are generally not as bright as standard incandescent bulbs".

Due to lousy eyesight, I am not a fast driver at night, so bright tail lights are important to us.

Since I have the tail lights figured out I'm getting 4.2 volts on the brake light circut. I'm wondering if the brake light switch could be allowing curent across the switch? I'll dig into that today but I thought I'd see if any of you electrical people had any ideas. Dennis

Is this with the brake off?

Is the ignition on or off?

Are the headlights and/or parking lights on when you get this reading?

And where exactly are you measuring this voltage?

The ignition was off, the headlights were off. I didn't have the brake lights on. I measured the voltage in the brake light wiring and with the brake switch disconnected at the brake peddle. I thought maybe it was geting into the circut through the cruise control circut, but with the ignition switch there shouldn't be any voltage. Maybe I should start pulling fuses one at a time.

Happy Thanksgiving!!!

Getting ready to hit the road and noticed the left rear turn signal light isn't working. New bulb didn't do the trick. Read the bit about a bad ground wire. Sounds like that might be the issue. Any advice or pics to identify and instuct?

Thanks,
Matt

I have had issues with both the socket connections and the wiring. Pull the bulb out and check the socket base wires. Often the contacts are crusty or the springs are shot and they don't make good contact with the bulbs.

The next place to check is the wiring. Bad grounds are often the culprit but if the running light works it has ground to the socket. The wires originate in the front harness and the turn signal switch.

You did not specify gas, diesel, Regal, Regency or Breakaway so that is the best I can do.

If you have an 80's Regal here is the wiring diagram for an 86.

https://www.barthmobile.com/eve...&s=7031072951&cdra=Y

Good luck let us know.