Tomar 930DM Flasher

Introduction

Several years ago, I salvaged some TOMAR 930DM (Dual Mode) 12V alternating flashers from some Tomar lightbars. These flashers are incredibly reliable but wiring them outside of a factory lightbar can be a puzzle.

Unlike many modern flashers that switch the positive voltage, the TOMAR 930DM is a ground-side switching (negative-switched) isolated circuit module. This means the module keeps a constant +12V positive supply on the main lines and connects and disconnects the ground path to make the lights flash.

This guide will show you how to safely wire a TOMAR 930DM to control individual, isolated ground lights (like halogens or LEDs) using a 2-switch dashboard configuration to toggle between Alternating Flash and Steady Burn modes.

Important Note: This flasher will ONLY work with lights that have a separate ground wire. It will not work with lights that are grounded through their mounting.

The Wire Blueprint (Understanding the Plugs)

The TOMAR 930DM typically splits its wiring into two separate harness clusters. Because the system utilizes an isolated power-loop design, power must be active on both feeds for the module brain and the lighting grid to work. Following the wiring description and diagram below will help you identify each wire and understand how the module is intended to operate.

1. Control & Power Trigger (2-Wire Plug)

• Black Wire: Main system ground (connects directly to battery negative or clean chassis ground).
• Red Wire: Flasher circuit control trigger. When this receives +12V, it wakes up the flasher brain to start alternating the grounds.

2. Light Power & Ground Circuits (5-Wire Plug)

• Red Wire with Ring Terminal: Main +12V power feed. This is the single red wire that occupies the position opposite the empty cavity in the connector, rather than being paired with a BLUE or YELLOW wire. Note: The ring terminal may have been cut when the relay was removed from the lightbar.
• Paired Red & Blue Wires: Left Light Circuit. Note: The RED wire provides constant +12V; the BLUE wire is the alternating ground loop.
• Paired Red & Yellow Wires: Right Light Circuit. Note: The RED wire provides constant +12V; the YELLOW wire is the alternating ground loop.

NOTE: The paired wires have a waterproof plug on the end of them. I cut the plugs off because I couldn’t find a matching end to connect to them.

SAFETY NOTE: Two 55-watt halogen lamps can draw nearly 10 amps continuously. Always install a 15-amp inline fuse as close to the battery as possible to protect the wiring in the event of a short circuit.

How Dual-Mode (Flash vs. Steady) Works

The 930DM switches the negative side when alternating. When the light ground wires are connected to the BLUE and YELLOW wires, the module completes the circuits, causing the lights to flash alternately. If either light’s ground wire is disconnected from the BLUE or YELLOW wire and connected directly to chassis ground instead, that light stops flashing and remains illuminated.

You can control this by using two switches:

• Switch 1: Turns the power on/off to the lights
• Switch 2: By using 6-pin Double-Pole, Double-Throw (DPDT) On-On switch, you can switch between grounding the lights through the flasher (alternating) and the chassis (steady burn).

Wiring The Lights To Flash

Your Master On/Off switch will activate the entire system by feeding power to both the module brain and the high-current grid simultaneously:

1. Run a fused heavy-gauge wire from your Battery Positive (+) terminal to the Input of your Master Switch.
2. Connect BOTH the RED Wire (from the 2-wire plug) and the single RED Wire opposite the empty cavity in the 5-wire plug together. Attach them to the output of your Master Switch.
3. Connect the BLACK Wire to a clean chassis ground or battery negative post.
4. Connect the BLUE Wire to the negative ground wire of one of the lights, and the YELLOW Wire to the negative ground wire of the other light.
5. Connect each light’s positive (+12V) lead to the paired RED output wire on the TOMAR harness. The RED Wire paired with the BLUE Wire powers one light, while the RED Wire paired with the YELLOW Wire powers the other.

Wiring the Lights to Choose Between Flash and Steady Burn

Step 1: Wire the Positive (+12V) Side

Your Master On/Off switch will activate the entire system by feeding power to both the module brain and the high-current grid simultaneously:

1. Run a fused heavy-gauge wire from your Battery Positive (+) terminal to the Input of your Master Switch.
2. Connect BOTH the RED Wire (from the 2-wire plug) and the single RED Wire opposite the empty cavity in the 5-wire plug together. Attach them to the output of your Master Switch.
3. Connect the BLACK Wire to a clean chassis ground or battery negative post.
4. Connect the positive (+) power leads of your individual lights to their respective RED output wires on the TOMAR harness.

Step 2: Wire the Negative (Ground) Side via the DPDT Switch

Look at the back of your 6-pin DPDT switch. It has two parallel rows of three pins. Wire them exactly like this to safely swap the ground paths:

Switch Pins (Back View)	Row A (Left Light Loop)	Row B (Right Light Loop)
Top Pins (1 & 4)	Connect to Flasher BLUE wire	Connect to Flasher YELLOW wire
Middle Pins (2 & 5)	Connect to Left Light GROUND lead	Connect to Right Light GROUND lead
Bottom Pins (3 & 6)	Connect to Chassis Ground (-)	Connect to Chassis Ground (-)

Driver Control Operations

Once wired, managing your custom warning setup from the cabin is simple and intuitive:

• SYSTEM OFF: Keep the Master Switch flipped OFF. The system draws zero current and is completely safe.
• ALTERNATING FLASH: Flip the Master Switch ON and set the DPDT Mode Selector to the UP position. The light grounds route through the TOMAR flasher module, creating an alternating flashing pattern.
• STEADY BURN MODE: Keep the Master Switch ON and flip the DPDT Mode Selector to the DOWN position. The light grounds bypass the flasher module and connect directly to chassis ground, causing both lights to illuminate steadily.