Pilothouse Grounding - How'd Dodge Do It?

[Jocko_51_B3B]

I'm installing a whole new wiring harness I bought from Rhode Island Wiring. I'm keeping it mostly original for now except I'm adding a SignalStat 900 turn signal.  My question is on ground paths. Since the shop manual schematic doesn't show ground connections, I'm wondering how Dodge grounded the accessories and starter from the factory. Here's what I'd like to know:

1. What path did return current originally take from the front parking lights and head lights back to the engine block and battery? For example, there is a small hole, nut ,and bolt in the very back of my headlight buckets which look like a place for  the headlight ground wire, but how did ground current flow back to the battery from there? And how about these for good measure:

2. Windshield wiper motor?

3. Tail lights?

4. Starter?

5. Horn?

6. Dome Light?

7. Voltage Regulator

Believe me, I don't intend (or want) to run ground currents through rust-prone bolts or where one piece of bare rusting sheet metal touches another spot of bare rusting sheet metal. I just think that knowing how the factory provided for grounds might help me do a better job or give me some good ideas. So, I'm looking for detailed original ground path information if anyone still knows or remembers. I know I'm asking for a lot of detail, but I think it's good to know this stuff if for no other reasons than historical and how NOT to do it.

 

 

 

[stylesadamson]

Almost everything on our trucks were self grounded. The lights are single pigtail grounded through the fixture as opposed to dual pigtail with a power wire and a ground wire. Starter is effectively the same.

[Plymouthy Adams]

most all ground issues on components were direct connection to the body via the components mounting screws...light assemblies usually were a physical ground wire connection...AS AN ADDED NOTE....good clean physical connection at contact points and screw holes should be clean of rust and paint, use of star washer will go a long way in making a bite between ground and component and keep this connect longer...

Edited April 14, 2020 by Plymouthy Adams

[JBNeal]

In short, every circuit is grounded through each component body instead of a ground wire.  When parts were new and pristine, it worked well and was economical...but as corrosion set in, circuit perfomance diminished or failed outright because the ground path impedance would go sky high, which is not good on 6V systems.  By the 60s, ground wires started showing up on practically every component to improve reliability, driving up vehicle base price but that was offset by improved sales due to the perception that certain vehicles were more bulletproof than others with small changes like this.

 

Look at the path to ground for the Pilot-House horn:  a single wire goes through the steering gear shaft, a multi-piece ground contact switch prone to corrosion completes the circuit when the horn button is pressed, then the path continues through the steering gear shaft, into the gearbox, through the gearbox casting bolts to the frame, then try to figure out how the frame connects to the original ground location on the transmission case...that's a LOT of places where corrosion can build up, so it's no wonder that the horn doesn't work well on an unrestored 6V system.  In subsequent models, the horn button got that ground wire added to bypass all those corrosion points to make horn performance more reliable. 

[Jocko_51_B3B]

JB,

Thanks, I'm adding ground wires wherever I can. Here's my first, (maybe not last), attempt to ground the wiper motor (not sure what color wire to use so I used some yellow with three black tracers - 12 gauge should be plenty good).

 

 

 

I don't necessarily like the looks of this ground wire sticking out through that hole in the firewall, but I think it forms a reliable ground connection to the cab because the bolt threads into a flow-drilled hole. At least my ohmmeter says it's good. If I think of something better I'll change it. To depend only on a ground between the wiper motor mounting bracket and the bottom of the dash seems shaky to me. Beside that, I'm trying to avoid scraping new paint off the cab even if it is under the dash.

 

[JBNeal]

In automotive applications, black is generally a ground circuit...in higher voltage applications, green is ground.

 

One thing I did was add a ground wire from the battery cable, which I had grounded with a stud I made on a starter mounting bolt.  The stud is long enough for a hex nut + helical lockwasher to clamp the starter flange, the ground cable lug, and a jam nut + external star washer then a few threads extra for the main ground wire.  With the battery grounded to the starter, the starter turns a little faster but definitely has a direct path to ground.  The main ground wire can be attached to the frame rail to make it act as a buss bar, with ground wires attached to it as needed, for headlight area, taillights, fuel tank sender, cab, etc

Edited May 24, 2021 by JBNeal
added link

[The Oil Soup]

I added a ground strap from the engine to the firewall and from the engine to the frame.

[1950fargofn1]

I added ground straps from engine to frame, frame to cab, frame to dump box and frame to front clip (fenders, grill and hood).

After adding ground straps I noticed that the headlamps were a lot brighter. 

[Radarsonwheels]

Yep on my build I welded stainless studs to the frame in the back by the battery, in front of the firewall, and up by the radiator. They are all connected to the battery with heavy cable and a heavy cable is also ran to a starter mounting bolt to ground the block. 
 

Maybe overkill but my first remote battery installation- in the rear passenger trunk of a ‘72 dodge demon street machine- really cranked better with a heavy welding cable ground straight to the starter/engine block from the battery. With the ground just bolted to clean metal on the trunk floor/rear unibody frame stub it was harder to crank the worked stroker smallblock, especially when it was hot

[Radarsonwheels]

I’ve also done relays for the headlights and stuff like that which work but I decided they are not worth the extra spaghetti.