With all the different wires that clutter your Honda’s engine bay, it can be absolute hell trying to discern the wiring for its alternator’s 4 pin connector.
But it doesn’t have to be that way! Not only have we got wiring diagrams for you, but we’ll even show you what these seemingly random colored wires actually mean.
Without further ado, let’s get your Honda 4 pin alternator wired up correctly and spark some life into your ride!
Honda 4 Pin Connector Wiring Diagram
When looking at a wiring diagram for a Honda 4 pin alternator, you’ll come across several connectors and wires that all connect to different points within the vehicle’s electrical system.
One of the main connectors for the Honda 4 pin alternator is the B terminal (battery terminal), which serves as a connection for both the battery and the ground source.
The other connector is the 4 pin connector (alternator connector) itself. But unlike the B terminal that only connects with one white wire, the 4 pin connector has multiple terminals connected to different colored wires that serve a specific purpose.
What are the functions of each wire on the Honda 4 pin alternator connector?
A Honda 4 pin alternator connector has a black/yellow wire as a 12v power source, a white/blue wire for the battery light on the dashboard, a white/red wire connected to the ECM, and a white/green wire connected to the alternator.
| Main Connector | Terminal | Color | Function |
| B-Terminal | Battery Terminal | White | Connects to ground source |
| 4 Pin Connector | Terminal #1 | Black/Yellow | 12-Volt (+) Power Source for alternator and battery |
| 4 Pin Connector | Terminal #2 | White/Blue | Illuminates battery light for instrument cluster (ICU) |
| 4 Pin Connector | Terminal #3 | White/Red | Sends FR signal to engine control module (ECM D9) |
| 4 Pin Connector | Terminal #4 | White/Green | Sends ECU output signal (D10) to alternator |
The Honda 4 pin alternator wiring diagram will show you several wires of different colors that all have their own roles to play in letting current flow throughout the electrical system.
As mentioned earlier, only one of these wires connects to the B terminal or battery terminal, which primarily serves as a connection to the ground and also energizes the battery.
There are four other wires that are connected to the four terminals of the Honda 4 pin connector itself, and the color of these wires will also tell you about where they’re connected on the other end.
• Black/Yellow Wire – This wire connects to terminal #1 of the 4 pin connector and also serves as the 12-volt power source for both the alternator and the battery.
• White/Blue Wire – This wire connects terminal #2 of the 4 pin connector to the battery light in the instrument cluster (ICU). In the event that the alternator has become faulty, current will flow through it and trigger the battery light.
• White/Red Wire – This wire connects terminal #3 of the 4 pin connector to the engine control module (ECM). Its purpose is to provide information regarding the alternator’s current output by transmitting FR signals (D9) to the ECM.
• White/Green Wire – This wire connects terminal #4 of the 4 pin connector to the ECM, wherein the ECM sends an output signal (D10) back to the alternator informing it of the currently required output.
Just a disclaimer that the color codes listed for these wires are only meant to serve as a general guide, as the exact color of each wire may vary depending on the model and generation of your Honda vehicle.
What are the two connectors in a Honda 4 pin alternator wiring diagram?
The two main connectors in a Honda 4 pin alternator wiring diagram are the B terminal (battery terminal) and the 4 pin connector (alternator connector).
The B terminal connects to the ground source and powers the battery, while the 4 pin connector has 4 terminals that connect to electrical wires.
B Terminal (Battery Terminal)
As its name suggests, the B terminal connects to and provides power to the battery via its own specific wire. The B terminal’s wire (or B wire) is usually a solid white color in Honda vehicles.
However, the B terminal is actually located at the back of the alternator itself, so it is not to be confused with the actual positive (+) and negative (-) terminals that sit on top of the battery.
Furthermore, the B terminal also serves another purpose, which is to connect to the main ground source.
4 Pin Connector (Alternator Connector)
The other main connector in a Honda 4 pin alternator wiring diagram is none other than the 4 pin connector, which is basically the main point of contact where the alternator is connected to the different components that make up the vehicle’s electrical system.
Also called the “alternator connector”, the 4 pin connector on a Honda vehicle houses four different terminals or “pins”, hence its name.
These four terminals then connect to four individual wires of varying color depending on their function.
The most typical colors for the wires would be white/blue for the battery light wire, white/red for the wire that sends FR signals to the ECM (D9), and white/green for the wire that returns the ECU’s output signal (D10) to the alternator.
But again, this may not necessarily apply to every single Honda model made, which is why it’s still recommended to consult your owner’s manual or a professional mechanic for your particular Honda’s wiring system.
Honda Circuit Wiring Diagram Sample
As with the wiring diagram for the Honda 4 pin connector, the color codes for each wire of the Honda circuit wiring diagram can also vary depending on the specific model and generation of your Honda vehicle.
The particular wiring diagram shown above is for the charging system of the 8th-generation Honda Civic made between 2006 and 2011. It includes the alternator, voltage regulator, different relays and fuses, and more.
Frequently Asked Questions (FAQs)
