Trunk CCFL (Cathode) Accent Lighting Install with 3-Position Selector

Pick a 12-inch CCFL kit that includes an inverter box; computer-case and automotive CCFL kits both work. A single tube is usually plenty of light for a trunk, and later posters noted that a dual-tube setup can look overly bright once the inverter reaches full output, so choose accordingly. Decide up front whether you want the optional 6-pin selector switch (two input pins, four output pins) that lets you toggle between the stock bulb, off, and the cathodes; if you skip it the tubes simply run whenever the trunk lamp would normally light.

Before touching any wiring, remove the interior-lights fuse (fuse 6, 7.5 A) so the trunk-lamp feed is dead while you work. The original writeup claimed the fuse must go back in the same orientation or it will blow; two follow-up posters corrected this - standard blade fuses are not polarized, so their direction on reinstall does not matter electrically. Note the slot position anyway so reassembly is tidy.

Insert a flat-head screwdriver at one edge of the lamp housing, press in the retaining tab, and work the whole unit free of its opening. Unplug the blue factory connector from the back of the lamp and set the lamp and lens somewhere safe.

Peel back the foam and hard-plastic covering on the harness to expose bare wire - allow for stripping back a generous length, more than seems necessary at first. Cut the blue connector off the feed wire but leave a tail long enough to solder to later. Then pull the power lead up out of the top of the sheet-metal channel and trace it back toward its source at the rear of the trunk so you have slack to work with.

Solder an added length of your 12-volt wire onto the end of the freed power lead and cover the joint with heat-shrink. Route the extended wire neatly around the trunk, using black zip ties to keep it tidy, and feed it back through the hole in the metal channel where the switch and other leads will gather.

The small terminals that fit this switch are still slightly wider than its pins, so squeeze each one gently with pliers, then ease it open again with a small flat-head until it grips the pin snugly. Slide a piece of heat-shrink onto the wire first, insert the conductor into the back of the terminal, and crimp it down with a crimp tool or pliers; shrink the tubing over the joint to finish. Always position the heat-shrink before crimping.

Fabricate a short jumper for the factory bulb: solder the blue connector (with heat-shrink) to one end of a length of wire and put terminals on the other end using the method above. Route this jumper through the metal channel so the terminal end emerges alongside the power feed while the blue-connector end comes out at the trunk-lamp opening. Plug the blue connector back into the factory lamp and reseat the lamp in its housing.

Make a third cable with terminals on one end and, on the other, the connector that mates to the cathode inverter box. Route it through the metal channel to join the other leads. Mount the inverter inside the channel with 3M double-sided automotive tape; if the inverter has ventilation slots, orient them upward and set the box low in the channel so those slots stay clear for cooling.

Fix the cathode tubes along the sheet-metal channel with zip ties. Where a tube contacts bare metal, pad the contact point with 3M tape to stop it from rattling - the trunk's low-frequency speakers sit nearby and will otherwise buzz against the tubes.

The two central pins are the inputs and the four outer pins are the outputs. Land the power-feed terminals on the two center pins. Connect the stock-light pair to one outer pair of pins and the cathode pair to the other outer pair. Before energizing, confirm that no bare conductor can touch another or the bodywork, paying particular attention to the exposed factory bulb connector. Reinstall fuse 6 in its original slot.

Work the switch through its positions and verify all three states: factory bulb on, everything off, and cathodes on. Because the switch energizes the side opposite to where it is pushed, flip it each way to identify which outer pins are positive and negative and to confirm the tubes light. If nothing works, recheck the terminal-to-pin connections - sorting out the switch orientation can take a couple of tries.

Wrap electrical tape around the terminals and switch body to hold everything in place. Tuck the leftover wire back through the opening into the hollow section of the channel until only the switch protrudes, tucked out of sight. Do a final check that nothing is pinched or shorting, then close up.