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Magic Link Sign-In

1. 1Open 12voltwiz.vercel.app in your browser.
2. 2Click Sign In and enter your email address.
3. 3Check your inbox for a message from 12VoltWiz. Click Sign in in that email.
4. 4You are signed in automatically and returned to the editor.

The editor is divided into four primary areas:

Every action in the toolbar is an icon button. Hover any button to see its tooltip. Buttons that are active — Grid on, Snap on, vehicle data entered, canvas detached — glow amber.

File Group

Edit Group

View Group

Wire Defaults

The wire icon opens a popover to set the defaults applied to every new wire drawn:

Vehicle

The car icon opens a popover to record the vehicle's information. This data appears on exported PDFs and CSV files. The button glows amber when any vehicle data is present.

Pop Out — Dual Monitor

The Pop Out button detaches the canvas into a separate browser window that you can move to a second monitor. Both windows stay in sync — drag a component in the pop-out and the wiring table in the main window updates immediately.

The pop-out window includes its own Inspector panel. Click any component or wire in the pop-out and the Inspector appears on the right, the same as in the main window.

Typical dual-monitor layout: canvas on the large screen, main window (tabs, library, inspector) on the laptop or second screen. The button glows amber while the canvas is detached. Close the pop-out window to bring the canvas back to the main window.

Account

When logged in, your email address and plan appear in the top-right of the toolbar. Click to reveal a menu with your plan name and a sign-out option.

On a paid plan, two additional buttons appear in the toolbar file group: Save to Cloud and Open from Cloud. See Files & Export for details.

The canvas is the diagram workspace. Components are placed here, wires are drawn between their pins, and the diagram is arranged into a readable schematic.

Navigation

Placing Components

There are two ways to place a component from the Library:

• Drag and drop — click and drag a component from the Library onto the canvas and release where you want it.
• Double-click — double-click any component in the Library to place it at the center of the viewport. Consecutive double-clicks stagger each placement slightly so components don't stack.

Drawing Wires

1. 1Hover over a component. Small pin handles — dots at connection points — appear along its edge.
2. 2Click and drag from a pin handle to begin drawing a wire.
3. 3Drag to another component's pin handle and release to complete the connection.
4. 4The wire is created with the current Wire Default settings for color, gauge, and signal type.

Right-Click Menu

Right-clicking any component opens its context menu:

Right-clicking a wire shows a separate menu:

Component Labels

Canvas nodes display the component's brand and model name only. Spec details (voltage, capacity, amperage) are in the Inspector — keeping the canvas readable at any zoom level.

Pin Handles

Each component shows small pin handles at its connection points. Drag from a handle to start a wire. Click a handle (without dragging) to trace or identify it — connected pins highlight the full net; open pins highlight only that handle so you can locate it on a busy canvas. Click again to clear.

Some overland components show a small gold diamond instead of a round handle on certain pins. These are CAN bus ports — they are shown for reference but cannot be wired in the diagram. Hover the diamond for details.

Deleting

Select any component or wire, then press Delete or Backspace. To delete only a wire without selecting it first, right-click the wire → Delete Wire. Removing a component also removes all of its connected wires.

Multi-Select

To select multiple components at once, click and drag on empty canvas to draw a rubber-band selection rectangle. Any node the rectangle touches is included. You can also hold Shift and click individual nodes to add them to the selection one at a time.

With multiple nodes selected you can:

• Drag them all together as a group
• Delete them all at once with Delete
• Right-click the selection → Group to create a named Branch Group
• Right-click the selection → Save as Template to save the sub-diagram for reuse

Branch Groups

A Branch Group visually groups related components — such as all the connectors on a single engine loom branch — under a named label. It draws a bounding rectangle around the members and shows the branch name, making the diagram easier to read and navigate.

1. 1Rubber-band drag to select 2 or more components on the canvas.
2. 2Right-click anywhere on the selection. A prompt appears: "Group N nodes as branch."
3. 3Type a name for the branch — for example Injector Bank A or Passenger Firewall. The name is optional; leaving it blank names the group Branch.
4. 4Press Enter or click Group. A labelled bounding box appears around the selected nodes.

Waypoints

A Waypoint node (available in the Library) routes wires around obstacles without creating a functional component. Wires connect to it like any other pin, letting you bend paths into right angles or specific routes.

Annotations — Sticky Notes

Add a sticky note to the canvas to record assumptions, callouts, or to-dos directly on the diagram. Notes are purely visual — they are excluded from the BOM, wiring table, cutlist, validation, and every electrical calculation, so they never affect your part counts or checks.

1. 1Click Add Note in the toolbar. A note drops at the center of the current view.
2. 2Double-click the note to edit its title and body text.
3. 3Choose one of five colors (yellow, blue, green, pink, gray) in the Inspector, and drag any edge of the note to resize it.

The Library opens as a panel from the LIBRARY button in the tab bar. It has three tabs — Components, Catalog, and Templates — and contains every component available for placement on the canvas.

Components — by category

Catalog — ECU kits & harnesses

Library Modes

Three mode buttons at the top of the Library switch the panel between disciplines:

The selected mode is saved automatically and restored the next time you open the app.

Categories — Engine Swap Mode

Overland Library BUILDER PLAN

Switch to Overland mode to access the mobile power library. All pinout data is sourced from official manufacturer installation manuals.

Manufacturer Documentation

When a branded Overland component is selected, the Inspector shows links to the official installation manual and product page. Click PDF to open the manual in a new tab, or Product Page to go to the manufacturer's website.

Configurable Components ⚙

Components marked with ⚙ in their subtitle have adjustable properties. Select the component and edit its values in the CONFIGURATION section of the Inspector. Pins update dynamically as you change the settings.

Connector Families

The connector library covers the most common families used in automotive harness work. Each connector includes plug and receptacle variants with verified housing and terminal part numbers.

Using ECU Kits

1. 1Expand ECU Kits in the Library panel.
2. 2Expand a brand — Holley, Haltech, FuelTech, AcesEFI, and others.
3. 3Select the specific kit to see its included harnesses and connectors.
4. 4Drag the main harness node onto the canvas to place the system.

Search

The search bar at the top of the Library filters all components by name, part number, or brand. Results update as you type.

Templates

The Templates tab stores sub-diagrams you've saved for reuse — for example, a dual-fan relay setup, a 3-relay nitrous stage, or any other wiring block you find yourself building repeatedly.

Templates require a User plan or higher and are saved to your account so they're available across devices.

Saving a template

1. 1Rubber-band select the components you want to save (2 or more).
2. 2Right-click the selection and choose Save as Template.
3. 3Give the template a name, pick a category, and add an optional description.
4. 4Click Save. The template appears in the Templates tab immediately.

Placing a template

• Drag a template from the Templates tab onto the canvas to place it at a specific position.
• Double-click a template to place it at the center of the viewport.

Every node and wire in the placed template gets fresh IDs — placing the same template multiple times creates independent copies with no shared state.

When a component or wire is selected, the right panel switches from the Library to the Inspector, where properties can be viewed and edited.

Connector Reference Photos

For known connector families, a reference photo appears at the top of the Inspector when that connector is selected. The photo is accompanied by a colored family badge — green for Weatherpack, blue for Deutsch DT/DTM, purple for Delphi GT150, and so on — making it easy to visually confirm you have the right connector in hand before crimping.

Photos appear for standalone connectors dragged from the Library and for connector ends on expanded harness nodes. Families covered include: Weatherpack (GM), Deutsch DT / DTM / DTP, TE Superseal 1.5, Metripack 150, Delphi GT150, Bosch EV1 / EV6 injector, and Bosch LSU4.9 wideband.

Wire Inspector

Click any wire to select it and expose these properties:

Component Inspector

Click any component — connector, sensor, harness end — to see its details:

Pin Table — Tracing and NC Marking

The PINS section lists every pin on the selected component. Each row shows the connection status and a label.

• CONN — pin has a wire. Click the row to trace the entire connected net. Click again to clear.
• OPEN — pin has no wire. Click the row to identify it — the pin handle on the canvas highlights so you can locate it at a glance. Click again to deactivate. Click NC to mark it as intentionally No-Connect.
• NC (marked) — intentionally unused. Click the dot on the canvas or the row in the Inspector to identify it. Click ✕ NC to restore it.
• CAN (gold badge) — CAN bus port. Shown for reference only; cannot be wired in the diagram. Refer to the manufacturer's installation manual for CAN network wiring.

Battery Bank

When a battery node is wired to one or more other batteries, the Inspector shows a BATTERY BANK section with the computed topology and electrical result:

The DRC short-circuit check is suppressed for battery-to-battery wires. A separate error fires only if the same pair is wired both in series and parallel simultaneously.

Wire Inspector — Temperature Derating

The Wire Gauge Calculator and Fuse Sizing section both show an ℹ icon next to ampacity values. Hovering it displays:

Ampacity values in the calculator are based on bundled wiring at standard ambient temperature. For engine bay or exhaust-adjacent runs, use a heavier gauge than recommended or consult your wire manufacturer's derating chart.

A Harness Node represents a multi-connector wiring harness — for example, a Holley Terminator X kit harness. It is a special component with expandable connector ends that expose individual pins for wiring.

Controls

Typical Workflow

1. 1Drag the harness from the Library onto the canvas.
2. 2Click ⊞ to expand the connector ends.
3. 3Use ↕ or ↔ to arrange the layout to match your physical routing.
4. 4Draw wires from exposed pins to sensors, power sources, or other connectors.

Context-sensitive calculators appear automatically in the Inspector when the right component is selected. They use the diagram's own data — wire length from node positions, gauge already on the wire, load already entered — so there is nothing extra to configure.

Wire Gauge / Ampacity Calculator

Select any wire and scroll to the WIRE GAUGE CALCULATOR section in the Inspector.

1. 1Enter the Load (amps) the wire will carry continuously.
2. 2Enter the Run length (ft) — one-way distance.
3. 3The calculator shows the recommended AWG, current capacity headroom, and voltage drop at load.
4. 4Click Apply to update the wire gauge in the diagram.

Fuse & Relay Sizing Assistant

Select any fuse or relay node. The FUSE / RELAY SIZING section appears in the Inspector.

1. 1Enter the Load (amps) the protected circuit will draw.
2. 2The assistant calculates the correct fuse rating using the 125% rule (NEC/SAE standard): fuse = load × 1.25, rounded up to the next standard size.
3. 3For loads over 20A, a Bosch relay recommendation appears with its part number.

Bundle Diameter Calculator

Select a Branch Group node (created by selecting multiple wires and using the right-click menu). The BUNDLE DIAMETER section appears in the Inspector.

The calculator reads the gauge of every wire in the bundle, computes the packed-circle outer diameter using standard wire OD data, and recommends correctly-sized conduit:

12VoltWiz continuously checks the diagram for electrical errors and flags them in the Status Bar. Checks run automatically as you draw — nothing to trigger manually.

Gauge Warning Badges

When a wire connected to a power or ground pin is thinner than 14 AWG, an orange ⚠ badge appears at the midpoint of that wire on the canvas.

• Hover the badge to see the full warning — component name, pin, current gauge, and recommended minimum (e.g. "Battery 1 · B+: 18 AWG on power pin — use ≥14 AWG").
• Click the badge to select that wire and open it in the Inspector, where you can change the gauge immediately.

Status Bar DRC Indicators

All active errors and warnings appear as labelled buttons in the Status Bar. Each button shows a count and can be clicked to select the affected wires or components for inspection.

The tab bar below the toolbar switches between five views of the project. All output tabs update automatically as the canvas changes — switching tabs never modifies the diagram.

BOM — parts & wire types

Wiring Table — from/to/color/AWG

Cutlist — wire lengths by run

Net tracing visually highlights circuits through the diagram without changing anything. Three trace modes are available — all non-traced elements dim to make the active circuit easy to follow.

Net Trace — Follow a Circuit

Click any wire on the canvas. All wires electrically connected in the same net — the same continuous circuit — highlight together. Non-traced wires dim. Click the wire again or click empty canvas to clear.

Pin Trace — Start from a Specific Pin

Two ways to trace from a specific pin rather than a wire:

• Inspector pin row — select a component, then click any CONN pin row in the PINS section. The full net connected to that pin highlights.
• Canvas handle — hover a component to reveal its pin handles, then click a handle (without dragging). The net highlights from that pin outward. A small accent ring marks the active handle.

Click the same pin again, or click empty canvas, to clear the trace.

Color Trace — Highlight by Wire Color

The Status Bar shows a color swatch for every SAE color in use. Click a swatch to highlight all wires of that color across the entire diagram. Click the swatch again or the ✕ button to clear.

Status Bar

Local Save

Projects save as .12vw files — a JSON-based format storing the complete diagram, vehicle information, and settings. The file downloads to your computer.

Cloud Save USER PLAN AND ABOVE

On a paid plan, projects can also be saved to your account and opened from any browser — no file management required.

1. 1Click the cloud save button in the toolbar (cloud with up arrow). The project is saved to your account immediately.
2. 2To open a cloud project, click the cloud open button (cloud with down arrow). Your saved projects appear in a list — click any row to load it.

Export Formats

Diagram exports (PNG, PDF) are found in Toolbar → ··· More. The BOM PDF and the combined Build Sheet are generated from buttons in the BOM tab; the wiring-table and cutlist CSVs export from their own tabs.

Opening a File

1. 1Click the Open button in the toolbar (folder icon).
2. 2Select a .12vw file from your computer.
3. 3If unsaved changes exist, a confirmation prompt appears before the file loads.

12VoltWiz is a modern web application. It requires a current browser to function correctly.

12VoltWiz uses SAE J1128 standard color codes throughout — the same codes found in factory service manuals and professional harness documentation.

Stripe Notation

Many wires carry a base color with a contrasting stripe. Both are set independently in the wire Inspector. The notation is always BASE/STRIPE: