The General Motors High Energy Ignition (HEI) system was used in GM vehicles from the mid-1970s to the early 1990s. It is a reliable and cost-effective ignition system that provides a powerful spark to ignite the air/fuel mixture in the engine. The HEI distributor uses a unique wiring diagram that can be confusing for beginners. In this article, we will explain the HEI distributor wiring diagram step by step.
What is an HEI Distributor?
The HEI distributor is a popular ignition system used in GM vehicles. It contains the ignition coil, rotor, cam gear, and distributor cap. The HEI system provides a high-voltage spark to the engine’s spark plugs, which ignites the fuel and air mixture in the combustion chamber. The HEI system is known for its reliability and ease of installation.
One of the advantages of the HEI distributor is that it eliminates the need for an external ignition control module. The HEI system uses an integrated ignition module located inside the distributor. This simplifies the wiring diagram and reduces the number of components required for the system to work.
HEI Distributor Wiring Diagram
The HEI distributor wiring diagram can be confusing for beginners. However, it is relatively simple once you understand how it works. The HEI system uses a 4-pin or 5-pin ignition module, depending on the year and model of the vehicle. The wiring diagram for the HEI distributor is as follows:
| Wire Color | Description |
|---|---|
| Pink | Ignition Power |
| Red | Battery Positive |
| White | Tach Output |
| Black/Yellow | Ground |
The HEI distributor wiring diagram may vary depending on the vehicle’s year and model. However, the basic wiring diagram is the same for most GM vehicles that use the HEI system. Let’s take a closer look at each wire in the wiring diagram.
Pink Wire (Ignition Power)
The pink wire provides power to the ignition module. It gets its power from the ignition switch or the starter solenoid. When the ignition switch is turned on, it sends a signal to the ignition module, which then sends a signal to the coil to generate a spark.
The pink wire is hot only when the ignition switch is in the “on” position. If you have no power to this wire, check the ignition switch or the starter solenoid.
Red Wire (Battery Positive)
The red wire is connected to the battery positive terminal. It provides a constant source of power to the ignition module. The red wire should be connected directly to the battery positive terminal, and not to any other wire or terminal in the vehicle.
White Wire (Tach Output)
The white wire provides a signal to the tachometer. It gets its signal from the ignition module, which sends a signal to the white wire every time the engine fires. The tachometer uses this signal to display the engine’s RPM.
If you do not have a tachometer, you can leave this wire unconnected.
Black/Yellow Wire (Ground)
The black/yellow wire is the ground wire. It provides a ground connection to the ignition module. The black/yellow wire should be connected to a good ground point on the engine or chassis.
FAQ
Why is my HEI distributor not working?
There are several reasons why your HEI distributor might not be working. The most common cause is a faulty ignition module. If the ignition module is not functioning properly, it will not send a signal to the coil to generate a spark. Other possible causes include a faulty rotor, distributor cap, or ignition coil.
Can I use an HEI distributor with a non-GM engine?
Yes, you can use an HEI distributor with a non-GM engine. However, you will need to make some modifications to the distributor to fit it to the engine. You may also need to modify the wiring diagram to ensure that the distributor is receiving the correct signals.
Can I test the HEI distributor with a multimeter?
Yes, you can test the HEI distributor with a multimeter. You can test the resistance of the ignition coil and the primary and secondary circuits. However, it is important to follow the manufacturer’s specifications to ensure that the readings are accurate.
How do I install an HEI distributor?
Installing an HEI distributor is relatively simple. First, remove the old distributor from the engine. Then, install the new HEI distributor in its place. Connect the wiring harness to the distributor and the battery. Finally, adjust the timing and start the engine to test the distributor.
What is the difference between a 4-pin and 5-pin HEI distributor?
The main difference between a 4-pin and 5-pin HEI distributor is the number of connectors on the ignition module. A 4-pin module has four connectors, while a 5-pin module has five connectors. The 5-pin module has an additional connector for the knock sensor circuit, which is used in some GM vehicles.
Conclusion
The HEI distributor is a reliable and cost-effective ignition system used in GM vehicles. Understanding the HEI distributor wiring diagram is essential for troubleshooting and diagnosing problems with the system. By following the wiring diagram and the manufacturer’s specifications, you can ensure that your HEI distributor is functioning properly and providing a strong spark to ignite the engine’s air/fuel mixture.
