Help with Brake Backup flasher

Thread Starter

medic505

Joined Aug 7, 2022
8
Hi

I am a paramedic trying to design a brake light / Back up light flasher. I think I figured it out. If someone can take a look and tell me if this will work or if there is a better way to do it. also wondering if I need to be using diodes or resistors to protect the LEDs from surges?

I am sure I used the wrong symbols its been like 25 years since I took electronics in high school.

The way it is designed if I put it into reverse or hit the break lights it will disengage that item from the flashing circuit. So if I brake, back up lights will continue to flash, if I put it into reverse the brake lights will continue to flash.

When the flasher is off there is no power to the flashing pins (3) on the relays so neither light will be on, but if I hit breaks or back up it will activate the respective relay and power the lights.

Thanks
 

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crutschow

Joined Mar 14, 2008
30,455
if I put it into reverse or hit the break lights it will disengage that item from the flashing circuit. So if I brake, back up lights will continue to flash, if I put it into reverse the brake lights will continue to flash.
I don't understand(?).
Those two sentences seem to be contradictory.
 

Tonyr1084

Joined Sep 24, 2015
6,961
To clarify - if I have this right - you want the backup lights to flash when you step on the brakes and you want the brake lights to flash when you're backing up ? ? ? What happens when you're backing up and step on the brakes ?

I would imagine brake lights are less important when you're backing up, but messing with their function at all and having a breakdown in your system could render your backup lights non-functional when you're going forward. I'd be worried that an ambulance with faulty brake lights could be a serious hazard and huge liability should someone get hurt, especially if it's someone in the ambulance who's already injured and then a rear end collision occurs because of failed brake lights. Somebody's going to get sued. And who's responsible? Likely the person who modified the brake lights.

Me? I'd suggest leaving it alone. There's a reason why DOT regulations exist.
 

Thread Starter

medic505

Joined Aug 7, 2022
8
To clarify - if I have this right - you want the backup lights to flash when you step on the brakes and you want the brake lights to flash when you're backing up ? ? ? What happens when you're backing up and step on the brakes ?

I would imagine brake lights are less important when you're backing up, but messing with their function at all and having a breakdown in your system could render your backup lights non-functional when you're going forward. I'd be worried that an ambulance with faulty brake lights could be a serious hazard and huge liability should someone get hurt, especially if it's someone in the ambulance who's already injured and then a rear end collision occurs because of failed brake lights. Somebody's going to get sued. And who's responsible? Likely the person who modified the brake lights.

Me? I'd suggest leaving it alone. There's a reason why DOT regulations exist.

There is a relay on both the brakes and backup - both will be overridden if activated in normal manner.

Almost every emergency vehicle has this type of device on it, it is not a DOT violation.
 

Thread Starter

medic505

Joined Aug 7, 2022
8
Not really, as long as the relays will handle the load. You mentioned surges on the LEDs, are the BU and Brake lights in the vehicle LEDs from the manufacturer?

Yes.

Or I may have converted them I do not recall, either way there will be LED bulbs in them. There is a caution in the upfitter manual to splice in, in the trunk area as they have some precautionary devices in the system.
 

sghioto

Joined Dec 31, 2017
3,357
There is a caution in the upfitter manual to splice in, in the trunk area as they have some precautionary devices in the system.
Don't know what that means. Getting back to the LEDs, if they are original equipment or exact LED replacements I don't see any need for surge protection.
 

dl324

Joined Mar 30, 2015
14,905
They are not cheap.
That's because they've been approved by DOT, so you bear no legal or financial liability for any incidents caused by their use. If you use your own solution, you would bear responsibility for any incidents arising from its use.

As an example, if the flash rate you chose caused someone to have an epileptic seizure, you would be liable for any consequences.
 

Thread Starter

medic505

Joined Aug 7, 2022
8
That's because they've been approved by DOT, so you bear no legal or financial liability for any incidents caused by their use. If you use your own solution, you would bear responsibility for any incidents arising from its use.

As an example, if the flash rate you chose caused someone to have an epileptic seizure, you would be liable for any consequences.
Fair point.
 

Thread Starter

medic505

Joined Aug 7, 2022
8
Because you say that if put in reverse or hit the brake light it will disengage from the flashing circuit, but then you say they continue to flash.
So I'm confused about what does "disengage" mean.
If you look at the schematic there is a relay than will disengage the brake and backup light individually from the flasher.
 
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