Help with Stock 57 Chevy Truck Blinker/Brake Wiring

[69MyWay]

I am working on a 57 4100 series truck for my neighbors landscaper. He actually uses this truck daily in his business. It is about as stock as you would imagine for a vehicle that has been in continous service for 49 years.

Anyway, the brake/blinker on this truck is not a combo unit. In other words, the brake light switch goes straight to a dedicated pair of brake lights, and the blinker goes to a park/blinker pair of lights. There are FOUR lights on the back of the truck.

The blinker switch is a THREE wire unit not designed to run the brake signal.

Here is my question.

Can I put a diode in each brake light wire just before the lamp so all four lamps have brake lights and blinkers? That would prevent the power from backing into the other lamp when the blinker is on.

[69MyWay]

Oh...I forgot to mention he also has to hook a trailer up to this with standard combo lights. My thinking is that as long as I connected the trailer harness after the diode, it would allow for a pair of standard trailer lights to run.

Otherwise, there is no way to get the trailer to function with a seperate brake and blinker signal.

[AAW]

The question of "can I.." that you posted can typically be answered with a "Yes". However, without first hand knowledge of the turn signal switch in question as well as the condition of the truck wiring, it would be impossible for us to recommend that you modify these circuits in this manner.

There are many additional variables to consider and there's a liability factor involved when re-engineering a system that old in a way that doesn't coincide with its original intent without taking ALL of the necessary precautions.

If you want to get into greater detail about the tech specs, give me a call & I'll get the additional support for you.

[69MyWay]

I found out the turn signal switch is not set up to run a brake light through.

So, I wired it the stock way so that it has a seperate brake/blinker. I used the combo light to run the parking lights.

Then, I picked up a cool gadget at the parts store that converts a five wire car/truck to a standard four wire plug for trailers.

So, I am able to get that installed so he can safely and correctly haul his trailer and still have full lights on the truck.

However, I did figure out I could have used a pair of normally closed relays with the diodes to make it go combo,...or, I could get a different turn signal switch in the column that would have done it as well.