2013-2016 Subaru BRZ Engine Fuse Box & Harness: Decoding Part Numbers and Critical Differences

Symptoms of a Failing Fuse Box Assembly

A problem with the main fuse box and harness assembly can create confusing electrical issues that are often mistaken for other component failures. Because it powers so many different systems, symptoms can be widespread and intermittent.

Multiple, Unrelated Electrical Failures

This is the most common sign. You might notice that your radio, interior lights, and tail lights all stop working at the same time. Because these components are on different circuits, their simultaneous failure points to a problem at their common power source: the fuse box assembly.

No-Start or Intermittent Starting

The vehicle may refuse to start, but not in the typical way. You might press the start button or turn the key and all the accessories, lights, and radio come on as normal, but the engine doesn't even try to crank. This can happen intermittently, taking 5-10 tries before the car finally starts. This often indicates a fault in the power supply path 🎬 See how to solve a Subaru BRZ no-start issue. to the starter or ECU within the main harness.

Sudden Stalling or Limp Mode

A severe failure within the harness can cut power to the fuel pump or ECU while driving, causing the engine to stall without warning. The car might also go into a 'limp home mode,' where all warning lights on the dashboard illuminate, and engine power is drastically reduced. This is a serious safety issue.

Visible Damage

A physical inspection may reveal obvious problems. Look for melted plastic on the fuse box housing, green or white crusty corrosion on the terminals, or wires that have been chewed by rodents or damaged in an accident. Water intrusion from a bad cowl seal can also lead to severe corrosion over time.

Known Issues, Recalls, and TSBs

As of this writing, there are no widespread known issues, factory recalls, or Technical Service Bulletins (TSBs) issued by Subaru specifically for the engine bay fuse box and harness assembly on the 2013-2016 BRZ. Most failures are isolated incidents resulting from physical damage, water intrusion, or previous improper repairs. While some owners report various electrical gremlins, they are not typically traced back to a systemic design flaw in the harness assembly itself.

Buying a Used 2013-2016 BRZ Fuse Box & Harness Assembly

Due to the extremely high cost of a new OEM assembly, a used part is the most practical solution for most owners. A clean, inspected used OEM harness provides the exact same function as a new one for a fraction of the price. However, you must be extremely careful to buy the correct part.

CRITICAL: Match Your Transmission and Trim Level

This is the most important step. The harness assembly is different for vehicles with an automatic transmission versus a manual transmission. They are not interchangeable. Furthermore, there are different part numbers for the 'Premium' and 'Limited' trim levels, likely due to the wiring for options like factory fog lights and heated seats.

• Manual Transmission, Limited Trim (2013-2014): Part Number 81402CA130
• Manual Transmission, Limited Trim (2015-2016): Part Number 81402CA131
• Automatic Transmission, Limited Trim (2013-2014): Part Number 81402CA170
• Manual Transmission, Premium Trim (2015-2016): Part Number 81402CA121

Always confirm the transmission and trim of the donor vehicle before purchasing a used assembly.

Physical Inspection Checklist

When buying used, inspect the part carefully or get detailed photos. Look for:

• No Cut Wires: Ensure the entire harness is intact with no cut or spliced wires.
• Intact Connectors: Check that all plastic connector housings are present and not cracked or broken.
• No Corrosion: Look closely at the fuse and relay terminals for any signs of green or white powder, which indicates water damage.
• No Melted Areas: Inspect the fuse box itself for any signs of melting or heat distortion, which points to a severe short circuit.

Scion FR-S and Toyota 86 Compatibility

The Subaru BRZ is mechanically almost identical to the 2013-2016 Scion FR-S (which later became the Toyota 86). This is great news for buyers, as you can use a fuse box and harness assembly from an FR-S or 86 in your BRZ. The same rule applies: the donor car must have the same transmission and a comparable trim level to ensure all the connectors match.

Programming and Installation

Physically, however, this is a difficult job. Replacing the entire engine room harness is a labor-intensive process that involves disconnecting dozens of sensors and components, carefully routing the new harness through the firewall and around the engine, and reconnecting everything. While possible for an experienced DIY mechanic, it is a time-consuming task. A professional shop will likely quote several hours of labor for the swap.

Cost Comparison

The cost difference between new and used is significant for this part.

Frequently Asked Questions (FAQ)