What you need to do before touching the speakers

Replacing speaker wires in a 1999 Infiniti I30 means disconnecting the old wires from the speakers themselves and running new wire from your head unit (the radio) to each speaker location. You'll need to remove door panels and possibly trim pieces to reach the speakers, disconnect the factory wiring harness, and install new speaker wire — typically 16-gauge or 14-gauge depending on the distance and power.

Before you start, disconnect the negative terminal of your battery. This prevents electrical shorts if you accidentally touch two wires together while the ignition is on. Wait a few minutes after disconnecting to let the electrical system discharge.

Gather your tools: a socket set or wrench for battery terminal, a panel removal tool (a plastic pry tool, not a screwdriver), wire strippers, a crimper if you're using crimp connectors, electrical tape, and new speaker wire. You'll also want a wire diagram specific to the 1999 I30 — your owner's manual or a service manual from a Nissan dealer will show which wires go to which speakers and what colors they are.

Key Takeaways

  • Disconnect the negative battery terminal before starting any electrical work to prevent shorts and damage to the head unit.
  • The 1999 I30 has four speakers (front doors and rear doors), and each one connects to the head unit through a separate pair of wires that run through the door jambs and under the carpet or trim.
  • Remove door panels by unclipping plastic trim pieces and unscrewing hidden fasteners behind the door handle and armrest — the speaker itself usually sits in a bracket behind the door panel.
  • Use 16-gauge or 14-gauge speaker wire depending on the run length, and match positive and negative wires by color or by marking them with tape before you disconnect anything.
  • Crimp connectors onto the new wire ends and connect them to the speaker terminals, or solder the connections if you have a soldering iron — soldered connections are more reliable than crimped ones.

Removing the door panels to access the speakers

Start with the front doors. Open the door and look for the power window switch panel on the armrest — it usually clips in from the top. Gently pry it upward with your plastic panel tool and disconnect the electrical connector behind it. Set it aside.

Next, remove the door handle trim. On the 1999 I30, there's usually a small screw or clip behind the interior door handle. Once that's out, the entire handle trim piece pulls away. Look for any screws along the bottom edge of the door panel and remove those as well.

The door panel itself is held in by plastic clips around the perimeter. Starting at the bottom, gently pry the panel away from the door frame using your plastic tool. Work your way around — the clips will pop out with a little pressure, but don't force it or you'll crack the panel. Once all the clips are free, the panel lifts away. You'll see the speaker mounted in a bracket behind it, usually held in by three or four screws.

Repeat this process for the rear doors. Rear door panels are similar but may have fewer trim pieces to remove. Once the panel is off, you'll see the rear speaker in its bracket.

Disconnecting the old speaker wires

With the door panel off, locate the speaker connector — a plastic plug with two or three wires coming out of it. The 1999 I30 uses a straightforward two-wire connection: one positive (usually red or marked with a stripe) and one negative (usually black or plain).

Before you disconnect anything, take a photo of the connector with your phone so you remember which wire is which. Then gently pull the connector apart. If it's stuck, wiggle it gently side to side rather than pulling straight out.

Once the connector is free, trace the wires back into the door jamb. They run through a rubber boot that seals the door opening. You can either pull the old wires out completely and use them as a guide for the new ones, or cut them near the speaker and leave the rest in place — leaving them in place is easier because you don't have to fish new wire through the tight spaces.

If you're removing the old wires completely, pull them gently through the door jamb boot. They may be taped or clipped to the door frame, so cut any tape and remove any clips as you go. Once they're out, you can use them as a pull-through guide for the new wire.

Running new speaker wire through the door jambs

Measure the distance from your head unit location (usually under the dashboard on the driver's side) to each speaker. Add a few extra feet for routing around obstacles. Cut your new speaker wire to length — you need two separate wires per speaker (positive and negative), so cut four pieces total for a pair of speakers.

If you removed the old wires, tie the new wire to the end of the old wire with electrical tape, creating a smooth connection. Then pull the old wire back through the door jamb boot — the new wire will follow behind it. If you left the old wires in place, you'll need to fish the new wire through manually. This is tedious but doable: push the wire through the boot slowly, using a flashlight to see where it's going, and have someone guide it from the other end if possible.

Once the wire is through the door jamb, route it along the door frame and into the door itself. find it with electrical tape or clips every 12 inches or so to keep it from rattling. Leave about 12 inches of extra wire at the speaker end so you have room to work with connectors.

Repeat this process for all four speakers. Front speakers usually run down the sides of the engine bay and under the carpet; rear speakers run along the rear doors and under the rear seat area.

Connecting the new wires to the speakers

Strip about half an inch of insulation from each wire end using your wire strippers. You should see bare copper underneath.

If you're using crimp connectors, slide the connector onto the bare wire and use your crimper to squeeze it tight. The connector should grip the wire firmly — tug on it to make sure it doesn't slide off. Then plug the connector into the speaker terminal. Most 1999 I30 speakers use straightforward push-on connectors that slide onto metal tabs on the speaker itself.

If you have a soldering iron, soldering is more reliable than crimping. Heat the connection point for a few seconds, then touch solder to the joint (not directly to the iron) and let it flow around the wire and terminal. Remove the solder first, then the iron. Let it cool for a minute before touching it. Solder creates a permanent connection that won't corrode or loosen over time.

Make sure positive wire goes to the positive terminal (usually marked with a + or a red dot) and negative goes to negative (usually marked with a − or a black dot). Reversing them won't damage anything, but the speaker will play out of phase and sound thin.

Reconnecting the head unit and testing

Once all four speakers are wired, run the speaker wires back to the head unit location under the dashboard. If you're using the factory head unit, you'll need to remove it first to access the wiring harness on the back. If you're installing an aftermarket head unit, follow the manufacturer's instructions for connecting the speaker wires to the correct terminals on the back of the unit.

The factory head unit in a 1999 I30 uses a multi-pin connector on the back. You may need to cut this connector off and splice the new speaker wires directly to the factory harness, or use an adapter harness if one is available for your model. A Nissan dealer or a car audio shop can tell you which approach works for your specific head unit.

Once everything is connected, reconnect the negative battery terminal. Turn on the head unit and test each speaker — play music and listen for sound from all four locations. If a speaker is silent, check that the wires are fully inserted into the connectors and that positive and negative are not reversed.

Reassembling the door panels and trim

With the speakers tested and working, reinstall the door panels in reverse order. Start with the rear doors, then move to the front. Line up the clips around the perimeter of the panel with the slots in the door frame, then press firmly until you hear or feel the clips snap into place.

Reinstall the door handle trim and any screws you removed. Reconnect the power window switch panel and clip it back into the armrest. Make sure all trim pieces sit flush and don't rattle.

Close the doors and test the windows and locks to make sure nothing was damaged during removal. Play music again and listen for any new rattles from the door panels — if you hear one, the panel may not be fully seated. Pop it back off and reseat the clips.

Frequently Asked Questions

Can I use the old speaker wires if they're still in good condition?

You can reuse them if the insulation is intact and they're not corroded, but new wire is inexpensive and guarantees you won't have a connection fail later. If the old wires are damaged or the insulation is cracked, replace them — a short in old wiring can damage your head unit.

What gauge speaker wire should I use?

For the 1999 I30, 16-gauge wire is standard for factory speaker runs. If you're running wire more than 50 feet or powering aftermarket speakers with higher power requirements, 14-gauge is safer. Thicker wire (lower gauge number) carries power more efficiently over long distances.

Do I have to solder the connections or can I use crimp connectors?

Crimp connectors work fine if you use a proper crimper and squeeze them tight. Solder is more reliable because it creates a permanent bond that won't loosen or corrode, but it requires a soldering iron and a steady hand. Either method works for speaker wires.

What if I can't get the old wires out of the door jamb?

Leave them in place and fish the new wire through alongside them. It's slower, but it works. Use a stiff wire or a fish tape to push the new speaker wire through the rubber boot, and have someone guide it from the other end with a flashlight.

Why is one speaker quieter than the others after I finish?

Check that the positive and negative wires are connected to the correct terminals on that speaker. If they're reversed, the speaker will play out of phase with the others and sound much quieter. Swap the connections and test again.