How to Run Wire in the Firewall of a Nissan Altima

By David Lipscomb

Running wire through the firewall of a Nissan Altima involves using the factory harness.
i engine image by goce risteski from

The Nissan Altima is a popular vehicle in the Infiniti/Nissan family. Owners of the Altima often require access to the battery or engine compartment, when they run accessory wiring from the cabin. Finding the stock wiring harness location leading into the engine compartment is the method that allows wiring with or without the presence of a clutch. Running wires through the Altima's firewall, although challenging, is made easier when you know where to look.

Open the driver's side door. Get on your knees, and peer under the driver's side dash, close to the emergency brake. Alternatively, use the hand-held mirror to get your bearings under the dash.

Reach up under the dash by the emergency brake. Look for a bulge in the carpet padding about the size of a racquetball.

Pull the carpet padding down to reveal the wire harness protruding into the Altima's cabin from the engine compartment.

Carefully make a small "X" shaped slit in the rounded bulge of the harness' body, using the utility knife.

Push the wire from the cabin into the engine compartment. The harness boot is flexible enough to not require the use of a fiberglass rod or coat hanger to assist in pushing the wire through.

Head back under the hood. Look for the wire protruding up behind the engine's air filter enclosure. Pull it up and into the engine compartment as needed.

Tie down the wire under the dash in the cabin using the plastic zip ties, so that there is no risk of a foot or pedal catching it.