I read a few posts and found a few wiring diagrams on how to wire a 2 filament bulb for the brake lights and indicators. The problem is I dont have the same indicator switch as any of these diagrams and all of them show the brake wiring going through the indicator switch. My indicator switch has one supply and two output positions (Right, Left). If I connect the brake switch as on the diagram, the front indicators will also light up when the brake is applied and when I use the indicators both indicators will flicker. The only way to fix this is to make use of diodes. Any other suggestions?
The attached schematic shows typical turn signal switching when a dual filament bulb is used for brakes and turn signals.
The front bulbs must be switched seperatly from the rear.
The switching consists of (2) DPDT switches (double pole double throw, maintained).
If your existing switch must be retained, (2) relays could be used in place of the DPDT switches.
General purpose relays will be adequate for this. 12vdc coil with DPDT 10 amp contact rating.
What turn signal switch are you using? The turn signal switch in nearly every US-made steering column in the last 60 years has separate output terminals for the front and rear turn signal bulbs specifically for this reason. The rear lamps run through the brake switch first, the fronts do not.
Here's a dia I drew up awhile back using relays.......
I used a single electronic flasher, nothing special just one that was listed for a 67 Camaro.
I had to use a ON-OFF-ON toggle (DPDT), I couldn't get it to work without it because I needed to turn off the brake circuit when the turn signal was on.
I used a ON-OFF toggle (SPST) for the hazards
I used bosh style 5 pole relays (six total),there better relays for this app, but I used bosh style due to availability. I used some smaller ones that I salvaged from a dodge Dakota. All 6 relays taped together measure 1 ¾” by 1 ¾”
I assumed the brake switch would provide a +12v
How it works……..
Step on the brake (no turn sig) pwr is fed from the brake light switch to the 87a (NC) terminal on Relays 1a and 1b, out thru terminal 30 (Comm) into to the 87a (NC) terminal on Relays 2a and 2b, out thru terminal 30 (Comm) to the rear turn/stop lights……. None of the relays are energized.
Activate left or right turn signal (no brake light) intermittent pwr is fed from the single electronic flasher, thru the turn sig switch to the 87a (NC) terminal on Relay 3a or 3b, (depending Left or Right) and out thru terminal 30 (Comm), front turn light is also connected to terminal 30…… at the same time terminal 30 (Comm) provides power to the 87 (NO) and 86 (Coil) terminal on Relay 2a. Relay 2a activates and sends pwr thru terminal 30 (Comm) to the rear turn/stop light…… both front and rear turn bulbs light and flash….. due to the flasher. At the same time constant pwr is fed from a +12 volt source , thru the turn sig switch to the 86 (Coil) terminal on Relay 1a or 1b, the relay activates and disconnects terminal 30 (Comm).
Activate left or right turn signal and step on the brake….. basically the same as the turn, but when the relay 1a or 1b, activates and disconnects terminal 30 (Comm), which is the brake light feed, the brake light cannot illuminate….. hence the turn signal continues to flash, while the other side brake feed relay is not energized and the brake feed is still connected and the brake light remains on.
Activate the Hazards……. constant pwr is fed from a +12 volt source , thru the Haz switch to the 87 (NO) and 86 (Coil) terminals on Relay 3a and 3b. Relays 3a and 3b activate and flash all four lights…… the brake circuit is still in connected ….. so the brake will over-ride the turns and stay on.
looks and sounds complicated, but really wasn’t that hard to wire up.
I will have a look at the diagrams. I'm from South Africa and i'm using a universal indicator lever. Its not really standard for our cars to have a combined indicator and brake light.
Once again thank you for your responses. It difficult to get any response from our local Hotrod site.
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