What makes an engine platform popular with the performance aftermarket is ease of interchangeability. This is one of the many reasons the LS and LT engines took off so quickly after they were introduced. But even with these platforms being some of the easiest to work on and swap parts on, when it comes to engine control and throttle bodies, things can still get a little foggy. That’s  why we teamed up with Performance Systems Integration (PSI) to create this three-part series breaking down throttle bodies across the Gen 3, Gen 4, and Gen 5 small-block engines. We’ve already covered drive-by-wire throttle bodies with Gen 3 LSs and drive-by-cable LS applications, so today we’re going to wrap up LS and LT drive-by-wire throttle bodies.

The E40 ECM And Silver-Blade Throttle Body

As GM transitioned from Gen 3 to Gen 4 LS engines, they needed a more capable control system to support evolving emissions standards, higher performance, and advanced vehicle networks. This led to the introduction of the E40 ECM for the early 6.0-liter LS2, replacing the older P01 and P59 modules used in Gen 3 engines. The E40 brought with it a completely redesigned four-bolt throttle body with a larger 90-millimeter silver throttle blade. This setup eliminated the need for a separate throttle actuator control (TAC) module, with all control functions now integrated directly into the ECM.

Other than the silver throttle blade, the LS2 throttle body looks exactly the same as the newer LS3 throttle body, but is not interchangeable.

Vehicles using the E40 ECM and silver-blade throttle body setup include the 2005 to 2006 Chevrolet SSR, the 2005 to 2006 Pontiac GTO, the 2005 Corvette, the 2006 Trailblazer SS, and the 2005 to 2006 5.3-liter equipped mid-size SUVs like the GMC Envoy and Chevy Trailblazer. Although these applications featured the then-new Gen 4 engine block, they still used the older 24x crankshaft reluctor wheel carried over from Gen 3. Because of that, these throttle bodies and ECMs are not compatible with later Gen 4 systems that use the 58x crankshaft reluctor wheel. Since it was only offered for 2 years, the E40 is an extremely rare ECM. If you have one of these engines but don’t have the E40 controller, don’t worry, the guys at PSI have you covered and can provide you with several options to get your engine running.

The E40 ECM and silver-blade LS2 throttle body can only work with each other, which is difficult because the E40 ECM looks very similar to the E67. The E40 has a tall black connector and short blue and grey connectors whereas the E67 has a short blue connector and tall black and grey connectors.

Gen 4 Evolution: E38 And E67 ECMs

With the introduction of the 58x crankshaft reluctor wheel, starting in 2007, GM upgraded its electronic control hardware further. Two ECMs took over at this stage: the E38 and the E67. These controllers were designed to be fully compatible with CAN-bus networked systems, and allowed greater flexibility for tuning and diagnostics.

The new body style 2007 trucks received a new intake manifold with the updated four-bolt throttle body mounting pattern from the LS2 and a new 87-milimeter throttle body. The cars received a new throttle body too, which looks identical to the LS2 throttle body but with a gold-colored throttle blade. Even though these two newer throttle bodies have the same bolt pattern and 6-pin electrical connector, the electronics inside are different, and they are not interchangeable.

GM engineered new ECMs to pair with these improved throttle bodies.. These new control modules can be identified by either an E67 or E38 stamp on the body, similar to how it is stamped on the E40 modules. GM continued to use these two ECMs for the rest of the Gen 4 LS production cycle, and they are the preferred control modules for 58x LS swaps.

The aluminum case for the E38 ECM is the same size and design as the E40 and E67, but with only two connectors.

You can see the factory applications for each ECM in the charts below. Note that the factory supercharged applications, the LS9-powered C6 ZR1 Corvettes and the LSA-powered ZL1 Camaros and CTS-Vs, are all controlled by the E67 ECM. It is recommended to use this control module if you are swapping one of these factory-supercharged LSs as these ECMs have higher capabilities for boosted engines. Something to keep in mind, if using a factory non-supercharged Gen IV engine, with a factory style supercharger like one off an LSA, PSI recommends sticking with the E38 ECM, as they offer a direct plug and play harness to work with this application that won’t require expensive coil and injector sub-harnesses. 

The E67 ECMs have three harness connections and can be found in vehicles like the CTS-V, ZL1, C6 ZR1, and Chevrolet Performance harness kits.

Gen 5 LT Architecture: Digital Control and E92 ECMs

In 2014, GM debuted the Gen V LT engine lineup, marking a complete departure from prior LS-based platforms. The new architecture included direct injection fuel systems, increased compression ratios, and redesigned cylinder heads. At the heart of the Gen V is the E92 ECM.

This new ECM is noticeably larger than earlier LS units and uses entirely different harness connectors. It was installed on early Gen 5 LT engines, including the L83, L86, LT1, and LT4 platforms. Because this ECM employs a digital communication protocol, and LS throttle bodies use analog signal-based communications, that means that LS and LT drive-by-wire throttle bodies are not interchangeable.

With all the changes and improvements with the Gen 5 LT platform comes changes with engine management. The E92 ECM is similar to the earlier Gen 4 LS control modules, but is much larger in size.

During the early years of E92 use, from 2014 through 2016, and in 2017 Corvette LT1 applications, GM utilized a four-pin fuel pressure sensor mounted to the driver’s side fuel rail. Starting in 2017 on other platforms, GM updated the design to a three-pin sensor and a slightly revised ECM, sometimes referred to as the E92a. It is critical not to mix these components, as the early ECM will not recognize the newer sensor, and the later E92a will not function with the earlier sensor. Mistakes in this area are common and frequently lead to diagnostic trouble codes and failed first starts with your swap.

LT Throttle Bodies: Unique Sizes

Although Gen 5 LT throttle bodies resemble LS units, including a familiar four-bolt flange and six-pin connector, they are fundamentally different. GM designed three primary variants depending on application: an 80-millimeter version for 5.3-liter trucks and SUVs, an 87-millimeter version for 6.2-liter trucks and sports cars like the Camaro and Corvette, and a massive 95-millimeter version exclusive to the supercharged LT5 engine found in the 2019 C7 ZR1. While these throttle bodies may appear swappable, each has its own mounting footprint. Even minor variances mean a direct replacement will often require an adapter plate or a completely different intake manifold.

The Gen 5 LT throttle bodies look identical to the Gen 4 LS truck throttle bodies, but the electronics inside are completely different.

The throttle control wiring, while still using a six-pin connector, has a different shape from previous LS versions. Furthermore, these throttle bodies use a digital signal, whereas Gen 4 units used an analog signal. Attempting to run an LT throttle body with an LS ECM, or vice versa, simply won’t work.

Matching Components for Success

Engine swaps demand precision, and one of the most critical decisions is selecting the right combination of ECM, throttle body, harness, and sensors. Each generation of GM small-block has unique requirements, and missteps here can derail an otherwise well-planned build, which inspired us to create this LS and LT drive-by-wire series.

For Gen 3 LS swaps, you’ll be using the P01 or P59 ECM with a three-bolt throttle body. These systems require a separate TAC module and communicate through analog signals. For early Gen 4 LS engines with the 24x reluctor, the E40 ECM and silver-blade four-bolt throttle body is the correct match, with no need for a TAC module. Later Gen 4 LS engines with the 58x crankshaft require either the E38 or E67 ECM. These controllers use gold-blade throttle bodies and, although they share electrical connectors, are not interchangeable with the LS2 throttle body.

Gen 5 LT engines use the E92 ECM, with throttle bodies sized to match engine displacement and horsepower output. The ECMs and throttle bodies communicate digitally, and fuel pressure sensors must match the ECM version exactly. Throttle bodies must also be chosen with care, as intake manifold flange mounting geometry can differ between the 80-millimeter, 87-millimeter, and 95-millimeter units.

Final Thoughts: Avoid Costly Mistakes

Throttle body, ECM, and Operating System compatibility issues are among the most common failure points in modern LS and LT engine swaps. Whether it’s trouble getting the engine to start, inconsistent throttle response, or persistent engine codes, mismatched electronic components can quickly bring your project to a halt.

Along with the label on the backside, the E40, E38, and E67 ECMs are stamped between the fins to identify them.

GM’s shift away from TAC modules and toward integrated, digitally controlled systems has greatly improved throttle response and reliability, but it also introduced more complex dependencies between components. Understanding how each ECM communicates with its matching throttle body, and how that changes across generations, is crucial to getting your build right the first time.

Working with experienced swap specialists like PSI can save time, money, and frustration. Their complete swap kits are built with compatibility in mind, matching the ECM, wiring harness, pedal assembly, and throttle body to your specific engine and goals. Whether you’re working with a junkyard pull or a crate engine, confirm your LS and LT drive-by-wire throttle body before beginning your install to guarantee success.