Relays and Fuses for Pilothouse Trucks

[Jocko_51_B3B]

 

Pilothouse truck owners know that an original Pilothouse electrical system is not complex compared to a modern vehicle. it also has some shortcomings that could be dangerous over time. It has no fuses or relays. Full headlight current goes through the headlight switch. There are no turn signals or flashers. My 1951 B3B electrical system was trash when I bought it so I'm replacing it almost entirely. I'm replacing the wiring completely with an original reproduction harness. I'm keeping it 6V.  I'm keeping the original generator and the original headlight and panel switches which still work fine. I want to install headlight relays for the low and hi beam headlights to take the load off the headlight and dimmer switches. I'm going to install a Signal Stat 900 turn signal/flasher unit. I've installed dual filament 6V bulbs in the front parking lights and tail lights so I'll have full turn signals front and rear, front parking lights, and brake lights (of course). I'm familiar with how to hook up headlight relays, but I'm getting down to some nitty gritty questions...

1. Can someone suggest good quality 6V headlight relays?

2. Where are the best locations in the circuit to include fuses (and what values)? In other words, what loads would it be wise to protect with fuses?

3. Does it make more sense for Pilothouse trucks to use inline fuses in various places or to install a fuse panel on the firewall? (A fuse panel seems like it would add extra wiring and complexity although it would look nicer.)

4. Is it better to use circuit breakers for the headlights instead of fuses?

Any other wiring/circuit suggestions/ideas are very much welcome. (Better to get some experienced advice before trying to re-invent the wheel.)

 

 

[JBNeal]

Some folks swear ya gotta put in a fuse box, some folks think inline fuses are adequate...it all seems to be personal preference as soon as ya start deviating from the original wiring installation.  For reliability, I recommend putting fuses under the dash out of harm's way...for example, on the firewall above the starter pedal, directly behind the speedometer might be a decent spot that can be accessed for service and near the original hole in the firewall where the wiring harness penetrates.

 

additional information - Modified Wiring Diagram with Headlight Relays + Turn Signals

additional information - headlight relay instructions 

[stylesadamson]

Use 2 small blade fuse boxes on the firewall. One for switched items and one for always hot. I’ll post some pics later. Relays on any high current items like horns. I have switched every light on my 52 to led so all are low current.

[Jocko_51_B3B]

JB,

I took a look at your CAD drawing and I stand corrected about the original wiring having no short circuit protection. Your diagram made me get out the book and check things out a little better. I didn't know that the small box hanging off the headlight switch is a breaker. Same for the device stuck onto the wiper switch. The only thing I noticed was that my shop manual rates the wiper switch breaker for 12A instead of 30A. I wonder if it's a good idea to check the breakers by briefly applying 6V across them. Your CAD drawing is nice! I had put an almost identical diagram together with photocopies, scotch tape, and with pencil lines going all over the place. Your drawing is a whole lot better to work from. I recommend it for anyone adding turn signals especially.

[Jocko_51_B3B]

Styles,

A horn relay sounds like it might be a good idea, but how essential is it? Headlights could be on for hours, but horns only get energized for a second or two. Just wondering.

[Plymouthy Adams]

it is not the time the device is drawing current as much as it is for the contacts of the switch making and breaking said current...

[kencombs]

Kits like this make a lot of sense to me.  Similar kit will be used on my 56 PU.  Not the greatest quality I'm sure, but a lot of parts for the money.

https://www.ebay.com/itm/universal-wire-harness-kit-For-Car-Hot-Rod-Street-Rod-XL-12-Circuit-Wires/133307013302?hash=item1f09b798b6:g:sRgAAOSwe2JeIR5a

 

Add relays if needed/wanted either near the fuses or load as desired.

[stylesadamson]

[Jocko_51_B3B]

I thought these were a good deal:

https://temcoindustrial.com/catalogsearch/result/?q=CN0364

I'll use one for the HI beam, one for the LO beam, one for the horn, and one for a spare.