LS ECU Just Swap Tune: A Comprehensive Guide

The process of swapping an engine control unit (ECU) or transmission control module (TCM) has become increasingly popular among car enthusiasts. One of the key considerations in this process is ensuring that the new unit can communicate effectively with the vehicle's other systems. In this article, we will explore the basics of ECU communication and provide a comprehensive guide on how to swap an LS ECU while keeping in mind the importance of proper communication.

Understanding ECU Communication

ECU communication refers to the way in which the engine control unit sends and receives data with other components within the vehicle. There are several types of buses that can be used for this purpose, including the PCI bus, CCD bus, and CAN bus. In some cases, it may be possible to eliminate certain buses or use a combination of buses to achieve effective communication.

CAN Bus Communication

The CAN (Controller Area Network) bus is a popular choice for ECU communication due to its high speed and reliability. When using the CAN bus, it is essential to ensure that both wires are properly connected and terminated. This can be achieved by using a 120 ohm resistor between the two CAN wires.

PCM Flashing

When flashing a PCM (Powertrain Control Module) or other control module, it is often necessary to have an ECM (Engine Control Module) on the bench with it. Alternatively, you may need to add CAN termination to ensure effective communication.

Tuning Tools and Current Draw

Most tuning tools draw close to 0.1 amps of current, while most modules will draw under half an amp of current at 12v with very few exceptions. It is essential to consider the power requirements of your ECU when selecting a tuning tool or designing a custom harness.

Pinout Considerations

When working with ECUs and control modules, it is crucial to understand pinouts and how they relate to specific components. Some pins are interchangeable with others, especially low reference (grounds), 12v power pins, and sometimes multiple CAN pairs. This can make it easier to connect the new ECU or module to your vehicle's wiring harness.

OBD2 Port Requirements

The OBD2 port requires constant 12v on pin 16 and grounds on pin 4 and 5 in addition to the communications bus wires outlined below. It is essential to ensure that these requirements are met when connecting an ECU or control module to your vehicle's wiring harness.

Wiring Color Codes

When depinning connectors, it is essential to pay attention to wire colors and ensure that they make sense. Grounds can often be identified by their dark brown, tan, black, or other earthy tones, while 12v ignition wires are usually pink or orange. Serial data lines are typically green or purple, and CAN wires on GM vehicles may have a distinctive tan color with stripes.

Disclaimer

Use of these pinouts is at your own risk. Harness connections marked with a * do not work with basic bench harness kits and would require a custom pinout or 16-pin version. Anything marked with partially works in certain situations, so be sure to review the note in each section for details.

If you are interested in building your own bench harness kit or parts list, please click here for more information. With this comprehensive guide, you should have a solid understanding of how to swap an LS ECU while ensuring proper communication with your vehicle's other systems.

LS ecu just swap tune