Trailer Wiring Harness for a 1957 Chevy Pickup Truck

Question:

My father in law has a 57 chevy pick up and he wired a 4 pole trailer hitch up. To do this we uses a converter to go from 5 wires on truck to 4 wires for plug. However he has put this converter on from Napa BK 7551086 twice and each time it has burned out and stopped working after about 6 months. I was wondering if you had a more heavy duty type of product that would work?

asked by: Matt

Expert Reply:

The first thing to determine is why the other converters stopped working so soon. Modern converters are designed to work on 12 volt systems with a negative ground. Many older vehicles used a 6 volt system and/or positive ground electrical system. Make sure that the 1957 Chevy Pickup truck is a 12 volt, negative ground system.

It is also possible that the trailer has enough lights to overdraw the converters. Converters have amperage ratings and if exceeded that can cause them to blow. The light housings may say their amperage draw. Otherwise you would have to power the lights and test the amperage they draw using a meter such as # PT89ZR.

And if the trailer has a short somewhere that could be causing the problem. Inspect the trailer and vehicle side connectors and make sure they are clean and free of corrosion. Inspect the trailer wiring too for any pinched wires or exposed copper strands and fix as needed. Make sure the ground for the connector and the light grounds are connected to clean and corrosion free bare metal surfaces.

I recommend going with Upgraded Heavy Duty Modulite # C59496. It has input wires for right turn signal, left turn signal, brake lights, and running lights. The white ground wire will need to be attached to a clean metal surface.

This converter also requires a direct connection to a 12 volt battery (provided the vehicle has one). This connection is what actually powers the trailer lights so the draw will not be coming from the tail light wiring on the truck.

This converter is rated for Max. stop/turn light: (4.2 amps) and Max. tail lights: (7.5 amps).

If the truck does not have separate bulbs for brake lights and turn signals (that is, if the turn signals and brake lights are combined on the same bulb, one on each side of the truck) then you would ground the red input wire with the white wire.