1981 Porsche 928 Green Wire Part Number: Identification and Replacement Guide

If you're restoring or repairing a 1981 Porsche 928, you've likely encountered a green wire that's frayed, broken, or just needs replacement. Identifying the exact part number for that wire can be tricky because the 928's wiring harness is complex and uses color codes that vary by circuit. This guide will help you locate the correct part number for the green wire in your specific application, whether it's for the engine bay, interior, or lighting system.

Understanding Porsche 928 Wiring Color Codes

Porsche used standardized color codes for their wiring harnesses in the late 70s and early 80s. In the 1981 928, green wires are typically used for specific functions:

• Solid green: Often indicates a ground or signal wire for sensors, such as the oxygen sensor or coolant temperature sensor.
• Green with a stripe (e.g., green/black, green/white): Used for switched power or control signals to components like the fuel injection system, ignition coil, or instrument cluster.

However, color alone isn't enough to identify the part number. You need to know the wire's location, gauge, terminal type, and the specific harness section.

Where to Find the Part Number

Factory part numbers for individual wires in the 1981 928 are not typically sold as separate pieces. Instead, they are part of a larger harness assembly or a repair wire kit. Here's how to find the right number:

1. Check the Wiring Diagram

Obtain a factory wiring diagram for the 1981 Porsche 928. This will show you the circuit that the green wire belongs to. Look for the wire's connector numbers, splice points, and the components it connects. The diagram often lists the part numbers for the entire harness, but you can narrow down the section.

2. Identify the Harness Section

The 928's wiring is divided into several harnesses:

• Engine harness
• Body harness
• Interior harness
• Dashboard harness
• Rear harness

Each harness has a specific part number. For example, the engine harness for a 1981 928 with the 4.5L V8 might be 928 612 001 00 or similar. Within that harness, the green wire is just one piece. To get the exact wire, you need to order a repair pigtail or a replacement harness.

3. Use the Parts Catalog

Porsche's parts catalog for the 1981 928 (often available online or through dealers) breaks down the harness into sub-components. Look for "wire" or "cable" listings under the electrical section. You may find a part number like 928 612 123 00 for a specific wire with connectors attached. The green wire might be listed as "CABLE - GREEN" with a part number.

4. Contact a Specialist

If the catalog doesn't have the individual wire, contact a Porsche classic parts specialist or a vintage wiring supplier. They can often identify the wire by its color, length, and terminal style. Provide them with:

• The exact location of the wire (e.g., driver's side engine bay, near the fuse box)
• The connector type (e.g., single blade, round pin)
• The gauge (e.g., 16 AWG, 18 AWG)

Common Green Wire Locations and Part Numbers

Based on the 1981 Porsche 928, here are some frequent green wire applications and their typical part numbers (verify with your VIN):

Oxygen Sensor Wire (Engine Harness)

• Color: Green (solid) or green/black
• Location: On the front of the engine, near the exhaust manifold
• Possible part number: 928 612 009 00 (oxygen sensor harness) or a repair pigtail 928 612 011 00

Coolant Temperature Sensor Wire

• Color: Green/white or green/red
• Location: On the water bridge or thermostat housing
• Possible part number: 928 612 014 00 (temperature sensor connector)

Fuel Injector Harness Wire

• Color: Green with stripe (varies by cylinder)
• Location: Along the intake manifold, connecting to injectors
• Possible part number: 928 612 036 00 (injector harness sub-section)

Instrument Cluster Backlight Wire

• Color: Green (often for the tachometer or speedometer)
• Location: Behind the dashboard, near the cluster
• Possible part number: 928 612 072 00 (instrument cluster harness)

Note: Part numbers changed during production. Always cross-reference with your VIN and production date (for 1981, typically VIN range 928 810 0001 to 928 821 0000).

How to Order the Correct Wire

Once you have a potential part number, follow these steps:

1. Verify with a dealer: Provide the part number to a Porsche classic center or an online OEM parts supplier. They can check if it's the correct wire for your VIN.
2. Check for supersession: Some wires have been replaced by newer part numbers. Ask for the latest version.
3. Consider a repair kit: If the exact wire is no longer available, buy a universal repair wire of the same gauge and color. You can also use a pigtail that includes the correct connector.
4. Match the terminal type: The wire ends must match the factory connector. Use crimp terminals or solder connections as per the original.

Practical Tips for Replacement

• Disconnect the battery before working on any wiring to avoid shorts.
• Use heat shrink tubing to protect connections and maintain the factory appearance.
• Note the routing: Take photos before removing the old wire. The original routing often avoids heat sources and moving parts.
• If unsure, buy the whole harness: For a 40-year-old car, the entire engine harness might be a good investment. Prices range from $300 to $800.

Final Recommendation

For most 1981 Porsche 928 owners, the green wire part number will be specific to the circuit and harness subsection. Start by identifying the exact location and function using a factory wiring diagram. Then, look up the harness part number and cross-reference sub-components. If you cannot find the individual wire, purchase a used or NOS harness section that includes the green wire and splice it in. For the best results, contact a Porsche specialist with your VIN and wire details. They can sell you the correct repair pigtail or advise on an alternative.

Remember, using the original part number ensures proper gauge, insulation rating, and terminal fit. Your 928 will thank you with reliable electrical performance for years to come.