BYD Add-an-Ignition T-Harness User Manual & Setup Guide

Fitting the BYD Add-an-Ignition T-Harness? Need the instructions? No stress.

Every BYD in the range has the same catch for dash cam owners: the interior fuse box is all constant power, with no switched accessory (ACC) circuit to tap. Without one, your dash cam can't tell when you've parked. Our Add-an-Ignition T-Harness fixes that by giving your camera or battery pack a genuine ignition-on / ignition-off signal. Here's how it goes in and what to check.

Quick Facts

• What it is: a T-harness (Y-splitter) designed and custom-made for The Dash Cam Guys
• What it does: fits inline with an existing BYD loom that switches with the ignition, and gives you a switched output for your dash cam hardwire kit or battery pack
• Where it goes: behind the 12V socket, which means removing interior trim
• Tools: a plastic trim removal tool. No soldering, crimping or wire cutting
• Time: roughly 15 to 30 minutes for a confident DIYer
• Works with: dash cams with a hardwire kit, and dedicated dash cam battery packs

Note: "plug-and-play" means the wiring. Nothing gets cut, spliced or fuse-tapped, but you or your installer still need to pull a panel to reach the connector. It does not plug into the front of the 12V socket.

Confirmed BYD Fitment

Driving a BYD not on this list? Contact us before you order rather than guessing.

Installation Steps

1. Switch the car off. Carefully remove the interior trim panelling around the 12V socket to reach the factory loom behind it.
2. Unplug the factory connector from the back of the 12V socket.
3. Fit the T-harness inline: factory plug on one side, with the accessory feed passed straight through on the other.
4. Run the harness's switched output to your dash cam hardwire kit's ignition (ACC) input, or to your battery pack's ignition (ACC) input.
5. Connect your hardwire kit's constant and ground wires as its own manual describes.
6. Before refitting trim, use a test light to confirm the switched output is live with the car on and dead with the car off.
7. Refit the panelling, then turn on Parking Mode in your camera's settings. It should now arm when you switch off and disarm when you start up.

Common Questions & Troubleshooting

Why can't I just use a fuse tap like in other cars?

Because BYD's interior fuse box is all constant power. There's no switched ACC fuse to tap, so your camera has no way to tell driving from parked. This harness adds that missing signal.

The camera won't go into Parking Mode.

Check Parking Mode is turned on in the camera. Then confirm the T-harness is fully clicked in at both ends and that your hardwire kit's ACC wire is on the harness's switched output, not a constant source.

My 12V socket stopped working.

One of the connectors behind the socket isn't fully seated. Pull the trim again and make sure both sides of the T-harness click home.

Can I use it with a battery pack instead of a hardwire kit?

Yes. It works with dedicated dash cam battery packs as well as dash cams. Our parking battery pack is a popular pairing if you want to keep the draw off the car's battery.

I have a Sealion 5. Will it fit?

Not at the front console socket. Use the rear 12V socket, which does fit.

Do I need a professional?

It's a no-cut job, but it does mean pulling trim on a new car. If you're not comfortable with that, contact us and we can point you to an experienced dash cam installer.

Official User Manual

The Add-an-Ignition T-Harness is designed and made for The Dash Cam Guys, so this guide is the manual. If you get stuck, contact our team and we'll talk you through it.