How to Install a Wig Wag Module for Alternating Headlight Flashing
"Q: What does a wig wag module actually do?A: It makes two lights - typically headlights or auxiliary lights - flash alternately left-right instead of together, using a timer circuit that switches its two outputs out of phase with each other.
Q: Can I wire a wig wag module to my factory high-beam circuit?A: You can, but on many modern CAN bus vehicles that circuit doesn't carry a steady, tappable 12V signal, so the trigger may be unreliable. Wiring to a dedicated switch or a properly read CAN bus signal is more reliable than tapping the factory wire directly.
Q: Why is only one side of my wig wag flashing?A: This is almost always a wiring issue on that specific output - a bad connection, blown fuse on that leg, or faulty bulb/relay - rather than a fault in the module itself. Check that output's wiring in isolation before assuming the module has failed.
Q: Is wig wag lighting legal on the road?A: It depends on your country and your vehicle's classification, and rules differ between private vehicles and designated emergency or utility vehicles. Check current regulations for your specific vehicle class and country before installing one for public-road use.
Q: Do I need relays with a wig wag module?A: If your lights draw more current than the module's outputs are rated for directly, yes - wire the module's outputs to trigger relays sized for the lights, rather than running the lights' full current through the module itself."
Q: Can I wire a wig wag module to my factory high-beam circuit?A: You can, but on many modern CAN bus vehicles that circuit doesn't carry a steady, tappable 12V signal, so the trigger may be unreliable. Wiring to a dedicated switch or a properly read CAN bus signal is more reliable than tapping the factory wire directly.
Q: Why is only one side of my wig wag flashing?A: This is almost always a wiring issue on that specific output - a bad connection, blown fuse on that leg, or faulty bulb/relay - rather than a fault in the module itself. Check that output's wiring in isolation before assuming the module has failed.
Q: Is wig wag lighting legal on the road?A: It depends on your country and your vehicle's classification, and rules differ between private vehicles and designated emergency or utility vehicles. Check current regulations for your specific vehicle class and country before installing one for public-road use.
Q: Do I need relays with a wig wag module?A: If your lights draw more current than the module's outputs are rated for directly, yes - wire the module's outputs to trigger relays sized for the lights, rather than running the lights' full current through the module itself."
## What Is a Wig Wag Module and Who Uses It
A wig wag module makes a pair of lights - usually headlights or auxiliary driving lights - flash alternately, left-right-left-right, instead of both firing together. The effect is deliberately attention-grabbing, which is why it shows up almost exclusively on vehicles that need to be noticed fast: emergency and volunteer responder vehicles, tow trucks, utility and service fleets, and off-road or overland builds where a highly visible warning flash matters. It is a lighting pattern controller, not a light source - you're adding a wig wag module to lights you already have (or are installing at the same time), typically your existing high beams or a dedicated pair of auxiliary lights, to make them alternate instead of shining steadily.
Our own wig wag module (https://styrestrom.no/products/wig-wag/) is built to drive an existing pair of lights in this alternating pattern without swapping the bulbs or light bar themselves.
## Wig Wag Wiring Basics: How the Alternating Flash Works
At its core, a wig wag module sits between the vehicle's power/trigger source and the two lights, and it contains a timer circuit that repeatedly switches output A on while output B is off, then reverses, on a fixed or adjustable interval. Three connections matter for almost every install:
- Power in - a fused, switched 12V feed, so the wig wag only runs when you want it to, not whenever the battery is connected.- Two outputs - one to each light (or each side's relay, if the lights draw more current than the module's outputs are rated for).- Ground - a solid, dedicated chassis ground; a shared or poor ground is the single most common cause of uneven or stuttering flash patterns.
Some modules also include a trigger input so the wig wag pattern only activates when another circuit is live - for example, only when hazards are on - rather than being a separate always-on switch.
## Is Your Vehicle CAN Bus Controlled? Why It Matters for a Wig Wag Install
If you're planning to trigger the wig wag from your factory high-beam circuit rather than a standalone switch, the same CAN bus consideration applies here as with any auxiliary lighting install: on many modern vehicles, that circuit doesn't carry a clean, tappable 12V signal - it's a digital status message or a PWM-switched output. Wiring a wig wag module's trigger input directly to that circuit on a CAN bus vehicle can produce an erratic or non-existent trigger, which looks like a "broken" module but is actually a signal mismatch. Our guide on installing a CAN bus reader for auxiliary circuits (https://styrestrom.no/blo/installing-a-can-bus-reader-for-auxil/) and our overview of how CAN bus modules work (https://styrestrom.no/blo/canbus-modules-explained/) both cover how to get a clean, usable trigger signal on these vehicles rather than tapping the factory wire directly. If you're wiring the wig wag to a dedicated switch instead of a factory circuit, this isn't a concern - the module gets a clean signal by design.
## Tools and Parts Checklist Before You Start
- Wig wag module rated for your lights' combined current draw (or relays sized for the load, with the module switching the relays instead of the lights directly)- Inline fuse holder and fuse sized to the circuit- Ring terminal or panel bolt for a dedicated ground point- Butt connectors or a proper crimp/solder kit - twist-and-tape connections are the top cause of intermittent wig wag faults down the road- Wire loom or split tubing to protect runs through the engine bay- Multimeter, to confirm power, ground and trigger voltages before final assembly
## Step-by-Step Wig Wag Installation
1. Choose your trigger source. Decide whether the wig wag activates from a dedicated switch, from hazard lights, or from an existing circuit. A dedicated switch is the simplest and most reliable option for a first install.2. Mount the module in a dry, accessible location - inside the cabin, under the dash, or in a sealed engine-bay enclosure if the module is rated for it.3. Run and fuse the power feed from a switched 12V source close to the fuse box, sized appropriately for both outputs combined.4. Establish a dedicated ground. Run a separate ground wire to bare metal rather than daisy-chaining off another accessory's ground.5. Wire each output to its respective light or relay, keeping polarity and output assignment (left/right) correct so the alternating pattern looks intentional rather than random.6. Connect the trigger input to your chosen source from step 1.7. Test before final mounting. Power the circuit and confirm a clean, even alternating flash at the intended rate before securing wiring and closing panels.8. Secure and loom all wiring, away from heat sources and moving parts, and recheck connections after the first few drives.
## Common Problems: Uneven Flash, No Flash, Blown Fuses
- Uneven or stuttering flash - almost always a ground issue. Check for a clean, dedicated ground before suspecting the module itself.- Only one side flashes - check that side's output wiring and bulb/relay independently; a single bad connection on one output is far more common than a module fault.- No flash at all, but power confirmed at the module - check the trigger input; if it's wired to a CAN bus vehicle circuit rather than a dedicated switch, confirm you're getting a stable trigger voltage, not a PWM or digital signal that the module can't read directly.- Blown fuse on first power-up - check for a wiring short before replacing the fuse, and confirm the fuse rating matches the combined draw of both lights, not just one.- Lights flash but dimmer than normal - usually a voltage drop from undersized wire gauge over a long run; move to a heavier gauge or add a relay closer to the lights.
## Legal Considerations for Wig Wag Lighting
Rules on alternating or flashing forward lighting vary by country and by vehicle use (emergency/utility fleet vs. private vehicle), and they change from time to time, so this is genuinely a "check before you install" item rather than something with one universal answer across Norway, Sweden, Denmark, Finland and the UK. As a general rule, alternating headlight flash on a private passenger vehicle is far more likely to be restricted than the same feature on a designated emergency, tow, or utility vehicle. Confirm the current rules for your vehicle class and country with your local vehicle authority before wiring a wig wag module to be visible on public roads.
## FAQ
See the FAQ block for common installation questions and answers.
A wig wag module makes a pair of lights - usually headlights or auxiliary driving lights - flash alternately, left-right-left-right, instead of both firing together. The effect is deliberately attention-grabbing, which is why it shows up almost exclusively on vehicles that need to be noticed fast: emergency and volunteer responder vehicles, tow trucks, utility and service fleets, and off-road or overland builds where a highly visible warning flash matters. It is a lighting pattern controller, not a light source - you're adding a wig wag module to lights you already have (or are installing at the same time), typically your existing high beams or a dedicated pair of auxiliary lights, to make them alternate instead of shining steadily.
Our own wig wag module (https://styrestrom.no/products/wig-wag/) is built to drive an existing pair of lights in this alternating pattern without swapping the bulbs or light bar themselves.
## Wig Wag Wiring Basics: How the Alternating Flash Works
At its core, a wig wag module sits between the vehicle's power/trigger source and the two lights, and it contains a timer circuit that repeatedly switches output A on while output B is off, then reverses, on a fixed or adjustable interval. Three connections matter for almost every install:
- Power in - a fused, switched 12V feed, so the wig wag only runs when you want it to, not whenever the battery is connected.- Two outputs - one to each light (or each side's relay, if the lights draw more current than the module's outputs are rated for).- Ground - a solid, dedicated chassis ground; a shared or poor ground is the single most common cause of uneven or stuttering flash patterns.
Some modules also include a trigger input so the wig wag pattern only activates when another circuit is live - for example, only when hazards are on - rather than being a separate always-on switch.
## Is Your Vehicle CAN Bus Controlled? Why It Matters for a Wig Wag Install
If you're planning to trigger the wig wag from your factory high-beam circuit rather than a standalone switch, the same CAN bus consideration applies here as with any auxiliary lighting install: on many modern vehicles, that circuit doesn't carry a clean, tappable 12V signal - it's a digital status message or a PWM-switched output. Wiring a wig wag module's trigger input directly to that circuit on a CAN bus vehicle can produce an erratic or non-existent trigger, which looks like a "broken" module but is actually a signal mismatch. Our guide on installing a CAN bus reader for auxiliary circuits (https://styrestrom.no/blo/installing-a-can-bus-reader-for-auxil/) and our overview of how CAN bus modules work (https://styrestrom.no/blo/canbus-modules-explained/) both cover how to get a clean, usable trigger signal on these vehicles rather than tapping the factory wire directly. If you're wiring the wig wag to a dedicated switch instead of a factory circuit, this isn't a concern - the module gets a clean signal by design.
## Tools and Parts Checklist Before You Start
- Wig wag module rated for your lights' combined current draw (or relays sized for the load, with the module switching the relays instead of the lights directly)- Inline fuse holder and fuse sized to the circuit- Ring terminal or panel bolt for a dedicated ground point- Butt connectors or a proper crimp/solder kit - twist-and-tape connections are the top cause of intermittent wig wag faults down the road- Wire loom or split tubing to protect runs through the engine bay- Multimeter, to confirm power, ground and trigger voltages before final assembly
## Step-by-Step Wig Wag Installation
1. Choose your trigger source. Decide whether the wig wag activates from a dedicated switch, from hazard lights, or from an existing circuit. A dedicated switch is the simplest and most reliable option for a first install.2. Mount the module in a dry, accessible location - inside the cabin, under the dash, or in a sealed engine-bay enclosure if the module is rated for it.3. Run and fuse the power feed from a switched 12V source close to the fuse box, sized appropriately for both outputs combined.4. Establish a dedicated ground. Run a separate ground wire to bare metal rather than daisy-chaining off another accessory's ground.5. Wire each output to its respective light or relay, keeping polarity and output assignment (left/right) correct so the alternating pattern looks intentional rather than random.6. Connect the trigger input to your chosen source from step 1.7. Test before final mounting. Power the circuit and confirm a clean, even alternating flash at the intended rate before securing wiring and closing panels.8. Secure and loom all wiring, away from heat sources and moving parts, and recheck connections after the first few drives.
## Common Problems: Uneven Flash, No Flash, Blown Fuses
- Uneven or stuttering flash - almost always a ground issue. Check for a clean, dedicated ground before suspecting the module itself.- Only one side flashes - check that side's output wiring and bulb/relay independently; a single bad connection on one output is far more common than a module fault.- No flash at all, but power confirmed at the module - check the trigger input; if it's wired to a CAN bus vehicle circuit rather than a dedicated switch, confirm you're getting a stable trigger voltage, not a PWM or digital signal that the module can't read directly.- Blown fuse on first power-up - check for a wiring short before replacing the fuse, and confirm the fuse rating matches the combined draw of both lights, not just one.- Lights flash but dimmer than normal - usually a voltage drop from undersized wire gauge over a long run; move to a heavier gauge or add a relay closer to the lights.
## Legal Considerations for Wig Wag Lighting
Rules on alternating or flashing forward lighting vary by country and by vehicle use (emergency/utility fleet vs. private vehicle), and they change from time to time, so this is genuinely a "check before you install" item rather than something with one universal answer across Norway, Sweden, Denmark, Finland and the UK. As a general rule, alternating headlight flash on a private passenger vehicle is far more likely to be restricted than the same feature on a designated emergency, tow, or utility vehicle. Confirm the current rules for your vehicle class and country with your local vehicle authority before wiring a wig wag module to be visible on public roads.
## FAQ
See the FAQ block for common installation questions and answers.