tail light wiring

[slngsht]

DeanG posted a question on se7ens mailing list about wiring a combination brake/turn light into his car.

You can go buy the trailer kits that convert the 5 wire car systems (with amber turn signals) to 4 wire trailer systems. But what's the fun in that?

The cheap DIY way costs less than $1 (well, $4 if you count the gas for driving to radio shack and back).

Essentially, since the brake light does double duty as turn signal, you need to isolate the brake circuit from the turn circuit by using a diode, otherwise your turn signals will function like 4 way flasher.

Here is a diagram of what i did - you need to do it on each side.


[corrected wiring]

basically, on each side, there needs to be 2 paths to the light:

1. 12V--------- brake switch ----toggle switch------ light -------------ground
2. 12V--------flasher-------toggle switch--------light-------ground

I used two toggles to accomplish this each toggle has its center wired to the brake light. and the other 2 legs are in paths 1 and 2 above.

You will need to run the front turn signal lights separately (you need to use DPDT switches), otherwise your front turn signals will come on with your brake lights.

[powderbrake]

Ok, which way does the diode face? Arrow up? or arrow down?

[slngsht]

the diode has a solid bar on the end of the body. It does not allow flow from that side to the other. So the solid bar should face the tail light. I drew it as a blue area in the diagram.

BTW, if you get it backwards, it won't damage anything... brake lights won't come on.

[tnttim]

Um, the way you have it wired in if you were sitting at a light with your brakes on your turn signal would not be flashing in the back.

tnttim

[slngsht]

Um, the way you have it wired in if you were sitting at a light with your brakes on your turn signal would not be flashing in the back.

tnttim



heh, i'm pretty sure I checked for that, so either the schematic is wrong, or I didn't check for that condition. what you're saying makes sense though. I'll check it tonight. Looks like it's more involved.

[solder_guy]

That's why you really do need that trailer circuit to integrate the brake and turn signals ...

Rob

[slngsht]

That's why you really do need that trailer circuit to integrate the brake and turn signals ...

Rob

just needed to think harder :yesnod:

I have the circuit on paper here. will give it another shot today and post.

basically, on each side, there needs to be 2 paths to the light:

1. 12V--------- brake switch ---------- light -------------ground
2. 12V--------flasher-------turn signal--------light-------ground

I might end up with 2 push buttons to accomplish this, similar to what people have put on their steering wheel.

On each side, the button completes path 1 when not pushed, path 2 when pushed.

*If* I have thought about this right, I won't even need a 2nd flasher for hazards.

[MHKflyer52]

Hi Mazda,

Here is what I have used and it is very simple and works 100% with out any issues.

http://www.speedwaymotors.com/p/7079,384_Hi-Tech-Turn-Signal-Module-Deluxe.html?itemNo=91064070

Speedway Motors Pant Number 910-64070 $99.99 each.
HI-TECH TURN SIGNAL MODULE
DELUXE
Those of you running a T-bucket or roadster type steering column will love this one. Or if you are adding turn signals to an existing car, this is THE hot set-up.
It is available in two configurations: one taillight bulb per side (910-64070), or two (910-64050).

This module eliminates the need for turn signal flashers, hazard flashers and/or a traditional turn signal switch. It measures only 2-1/4" x 1-5/8" x 5/8" and will fit most anywhere. Simply mount two small momentary push button switches (available from Radio Shack) anywhere that is convenient, and connect the eight color coded wires into your harness.

The flash is consistent whether using incandescent or LED bulbs. 12 volt bulbs up to 6 amps total. Measures 2-1/4" x 1-5/8" x 5/8".

Here's how it works:

Press the appropriate button for 1 second and the turn signal light will flash for 7 seconds, then self cancel.

Press for 2 seconds and it will flash for 20 seconds, then self cancel.

Press for 4 seconds and it will flash for 75 seconds, then self cancel.

Press the same button a second time to manually cancel.

To activate the hazard flashers, press both buttons at once. To disengage, press again. (They will flash until disengaged).
THIS MODULE ALLOWS YOU TO USE ONE DUAL FILIMENT BULB PER SIDE TO OPERATE TURN, STOP AND TAILLIGHTS.

It also incorporates brake lights; applying the brakes will cause the rear turn signals to light as long as the brakes are held. If a turn signal is sent to the rear lights at the same time it will have priority over the brake lights and cause the corresponding light to flash. When the turn signal is canceled the brake light will resume.

[solder_guy]

Speedway Motors Pant Number 910-64050 $69.99 each.
HI-TECH TURN SIGNAL MODULE STANDARD (http://www.speedwaymotors.com/p/2366,384_Hi-Tech-Turn-Signal-Module-Standard.html) is for two rear bulbs per side and is $30 cheaper.

I would like to see the wiring instructions for these ..

Rob

[slngsht]

Martin, I really like those... when it's time to rewire the car, I'll have to cough up some cash for them.

For this week, I needed to convert my already hacked wiring harness to work with my lights, so that task is accomplished.

[DeanG]

I will be visiting the trailer place on Tuesday. Other than that I see a circut with three relays and two diodes.

One good thing. I found another brake system leak that would normally be hidden by the transmission tunnel cover.

[solder_guy]

While going though my spare parts bin I found a trailer circuit .. free to you .. Mazda.

Rob

[slngsht]

While going though my spare parts bin I found a trailer circuit .. free to you .. Mazda.

Rob


Rob, Thanks for the offer. I think with the rewire, I'll go with one of the circuits similar to what Martin posted. I know there are several variations. I'm headed out of the country this week and will be gone most of the month. After that the priority is front Aarms which are really the only major running gear item left on the list. It will be a while before I get to this.

The way I have wired it now, everything works. Only problem is my front parking lights are coming on with the brakes. This can be solved with DPDT switches, but it's a minor problem I'll just live with until the final wiring.

[MHKflyer52]

Hay Mazda,

The front parking lights coming on when the brakes are applied is good for when your spinning through the cones.......it lets everyone know if you have your foot on the brake.......HeHe...snicker...HeHe

Not like I have ever been their myself.

Have fun Down under. I should be landing in Phila Thursday afternoon for a week.

[solder_guy]

Old post ... alot of the modules listed here are from Signal Dynamics (http://www.signaldynamics.com/lighting_control.htm)