GM Gen III LS PCM/ECM: Electronic Throttle Equipment Guide

GM Gen III LS PCM/ECM: Electronic Throttle Equipment Guide

General Motors introduced electronic throttle, or drive-by-wire, with the LS1 engine in the 1997 Corvette. Electronic throttle was released before cable throttle for the LS-series engine family. In 1998, the Camaro and Firebird received a cable throttle LS1 engine. The GM trucks received LSseries engines in 1999 and, depending on make/model, were available with either cable throttle or electronic throttle. Navigating through the various electronic throttle equipment may be intimidating, but look carefully at the components to ensure success.

1997–2004 Corvette

The Corvette received the same electronic throttle equipment from 1997–2004. Other than a few GM part number updates, the equipment remained the same and electronic throttle equipment can be interchanged. The LS1 and LS6 engines received the same equipment. Everything changed (throttle body, pedal assembly, and TAC) when the LS2 engine was introduced in 2005.

With so many different throttle bodies, pedals, and TAC modules, you must take caution to choose the correct combination of components. Choosing the wrong components could result in no throttle response and an illuminated MIL lamp.

With so many different throttle bodies, pedals, and TAC modules, you must take caution to choose the correct combination of components. Choosing the wrong components could result in no throttle response and an illuminated MIL lamp.

Throttle Body

The Corvette throttle body is fitted with a TPS to monitor throttle blade angle. It is also fitted with a motor, operated by the TAC module, to open and close the throttle blade. The TPS housing contains two individual sensors with separate signals, low reference, and 5V circuits. The two TPS signals are monitored by the TAC module. As the throttle blade is opened, TPS sensor 1 voltage sweeps toward 5V reference, and TPS sensor 2 voltage sweeps toward low reference. These opposing signals are used by the PCM to monitor and make one throttle angle PID available.

This wiring diagram represents the 1997–2004 Corvette electronic throttle control system.

This wiring diagram represents the 1997–2004 Corvette electronic throttle control system.

LS2/LS3 Throttle Body: The 2005–2008 LS2/LS3 throttle body is a popular upgrade for the 1997–2004 LS1/ LS6 Corvette because it is electronically compatible with the 1997–2004 Corvette throttle control system. The larger 90-mm throttle opening and four-bolt pattern requires an intake manifold upgrade or an adapter plate. Aftermarket wire harness adapters are available for a plug-and-play installation.

The LS1 Corvette throttle body was the first electronic throttle body used with Chevrolet V engines. The throttle position sensor is mounted on the bank 2 side of the engine and the throttle shaft motor is mounted on the bank 1 side of the engine. The blade on this throttle body measures approximately 75 mm in diameter.

The LS1 Corvette throttle body was the first electronic throttle body used with Chevrolet V engines. The throttle position sensor is mounted on the bank 2 side of the engine and the throttle shaft motor is mounted on the bank 1 side of the engine. The blade on this throttle body measures approximately 75 mm in diameter.

The LS2 and early LS3 Corvette throttle body is an electronically compatible alternative to the smaller LS1 throttle body. The blade on this throttle body measures approximately 90 mm in diameter. Because the bore is larger and the four-bolt pattern is different than the three-bolt pattern of the LS1 intake manifold, the use of this throttle body requires a different intake manifold or adapter plate.

The LS2 and early LS3 Corvette throttle body is an electronically compatible alternative to the smaller LS1 throttle body. The blade on this throttle body measures approximately 90 mm in diameter. Because the bore is larger and the four-bolt pattern is different than the three-bolt pattern of the LS1 intake manifold, the use of this throttle body requires a different intake manifold or adapter plate.

The Corvette PCM and TAC monitor values from the two throttle position signals to identify proper operation of the throttle body. A DTC sets if a TPS value exceeds one of GM’s predetermined threshold values. This chart reviews the allowable operating ranges for each TP sensor (see “TPS Failure”) and the expected 0-percent and 100-percent voltage ranges for each TP sensor.

The Corvette PCM and TAC monitor values from the two throttle position signals to identify proper operation of the throttle body. A DTC sets if a TPS value exceeds one of GM’s predetermined threshold values. This chart reviews the allowable operating ranges for each TP sensor (see “TPS Failure”) and the expected 0-percent and 100-percent voltage ranges for each TP sensor.

This wiring diagram represents the 1997–2004 Corvette electronic throttle control system with LS2 throttle body. Notice the 5V reference and low reference for TP sensor 2 is not used because TP signal 1 and TP signal 2 share the same 5V reference and low reference from the TAC module.

This wiring diagram represents the 1997–2004 Corvette electronic throttle control system with LS2 throttle body. Notice the 5V reference and low reference for TP sensor 2 is not used because TP signal 1 and TP signal 2 share the same 5V reference and low reference from the TAC module.

This bench test of the LS2 throttle body demonstrates the electronic compatibility with the 1997–2004 Corvette electronic throttle system.

This bench test of the LS2 throttle body demonstrates the electronic compatibility with the 1997–2004 Corvette electronic throttle system.

The Corvette PCM and TAC monitor values from the three accelerator position signals to identify proper operation of the accelerator pedal assembly. A DTC sets if an APP value exceeds one of GM’s predetermined threshold values. This chart reviews the allowable operating ranges for each APP sensor (see “APP Failure”) and the expected 0- and 100- percent voltage ranges for each APP sensor

The Corvette PCM and TAC monitor values from the three accelerator position signals to identify proper operation of the accelerator pedal assembly. A DTC sets if an APP value exceeds one of GM’s predetermined threshold values. This chart reviews the allowable operating ranges for each APP sensor (see “APP Failure”) and the expected 0- and 100- percent voltage ranges for each APP sensor

Pedal Assembly

The LS1/LS6 Corvette accelerator pedal assembly has an APP sensor that contains three APP signals. The TAC module uses the three APP signals to determine absolute pedal position. APP sensor 1 signals voltage increases as the pedal is depressed. APP sensor 2 and sensor 3 signal voltage decreases as the pedal is depressed. The APP sensor signals are used by the PCM to monitor and make available one accelerator pedal percent PID.

The C5 Corvette (1997–2004) used only one accelerator pedal assembly. It is very popular because of its size and mounting configuration.

The C5 Corvette (1997–2004) used only one accelerator pedal assembly.
It is very popular because of its size and mounting configuration.

Throttle Actuator Control Module

There have been a few part number changes for the 1997–2004 Corvette TAC module but the Corvette TAC modules are interchangeable and General Motors maintains only one current part number for all 1997–2004 TAC modules. The Corvette TAC module looks identical to the 1999–2002 GM Truck TAC module, and even has the same harness connections, but carries a different GM part number and is not interchangeable with GM trucks.

The 1997–2004 Corvette and 2004–2005 Cadillac CTS-V use the same TAC module. Although these vehicles use a different accelerator pedal assembly and TAC-to-pedal wire harness, electronic throttle equipment can be used interchangeably among these vehicles.

The 1997–2004 Corvette and 2004–2005 Cadillac CTS-V use the same TAC module. Although these vehicles use a different accelerator pedal assembly and TAC-to-pedal wire harness, electronic throttle equipment can be used interchangeably among these vehicles.

2004–2005 Cadillac CTS-V

The 2004–2005 Cadillac CTS-V has much in common with the LS6 Corvette. General Motors used the Corvette TAC module, 2004 PCM (GM# 12586243), and LS1/LS6 throttle body with the LS6 CTS-V. In the same way that the LS1/LS6 Corvette can use the 2005–2008 LS2/LS3 throttle body, the LS6 CTS-V can use the 2005–2008 LS2/LS3 Corvette throttle body as a performance upgrade.

The 2004–2005 Cadillac CTS-V accelerator pedal assembly is unique. What is worth noting for Gen IV systems is that this pedal assembly uses the same housing (but a different harness connector) as some of the common LS-series applications (such as LS2 Trailblazer SS and Chevrolet Performance LS2/LS3/LS7 kits).

The CTS-V PCM and TAC monitor values from the three accelerator position signals to identify proper operation of the accelerator pedal assembly. A DTC sets if an APP value exceeds one of GM’s predetermined threshold values. This chart reviews the allowable operating ranges for each APP sensor (see “APP Failure”) and the expected 0- and 100-percent voltage ranges for each APP sensor.

The 2004–2005 Cadillac CTS-V accelerator pedal assembly is unique. What is worth noting for Gen IV systems is that this pedal assembly uses the same housing (but a different harness connector) as some of the common LS-series applications (such as LS2 Trailblazer SS and Chevrolet Performance LS2/LS3/LS7 kits).

The 2004–2005 Cadillac CTS-V accelerator pedal assembly is unique. What is worth noting for Gen IV systems is that this pedal assembly uses the same housing (but a different harness connector) as some of the common LS-series applications (such as LS2 Trailblazer SS and Chevrolet Performance LS2/LS3/LS7 kits).

This wiring diagram represents the 2004–2005 Cadillac CTS-V electronic throttle control system. Notice the only difference between the CTS-V and 1997–2004 Corvette is the accelerator pedal assembly and TAC-to-pedal wire harness.

This wiring diagram represents the 2004–2005 Cadillac CTS-V electronic throttle control system. Notice the only difference between the CTS-V and 1997–2004 Corvette is the accelerator pedal assembly and TAC-to-pedal wire harness.

Pedal Assembly

Even though a different accelerator pedal assembly was used with the 2004–2005 CTS-V, its APP sensor functions in similar ways to the 1997–2004 Corvette APP sensor. APP sensor 1 signals voltage increases as the pedal is depressed. APP sensor 2 and APP sensor 3 signal voltage decreases as the pedal is depressed. The APP sensor signals are used by the PCM to monitor and make available one accelerator pedal percent PID. Be careful to use a matching accelerator pedal and TAC-to-pedal wire harness. The Corvette harness does not work with the CTS-V accelerator pedal.

GM Truck

In general, trucks with a Gen III engine have two different electronic throttle configurations: 1999–2002 and 2003–2007. However, a careful look at the Gen III electronic throttle systems used in GM trucks from 1999–2007 reveals four specific configurations.

1999–2002

Throttle Body: The truck throttle body is fitted with a TPS to monitor throttle blade angle and a motor, operated by the TAC module, to open and close the throttle blade. The TPS housing contains two individual sensors with separate signal, low reference, and 5V circuits. The two TPS signals are monitored by the TAC module. As the throttle blade is opened, TPS sensor 1 voltage sweeps toward 5V reference and TPS sensor 2 voltage sweeps toward low reference. These opposing signals are used by the PCM to monitor and make available one throttle angle PID.

The GM truck throttle body looks much like the 1997–2004 Corvette throttle body but with the TPS and throttle shaft motor on opposite sides. The truck and Corvette share the same throttle shaft motor (which is not serviceable separately) but with opposing polarity. The blade on this throttle body measures approximate 75 mm in diameter.

The GM truck throttle body looks much like the 1997–2004 Corvette throttle body but with the TPS and throttle shaft motor on opposite sides. The truck and Corvette share the same throttle shaft motor (which is not serviceable separately) but with opposing polarity. The blade on this throttle body measures approximate 75 mm in diameter.

Pedal Assembly: The 1999–2002 truck accelerator pedal assembly contains an APP sensor that contains three APP signals. The TAC module uses the three APP signals to determine absolute pedal position. APP sensor 1 signals voltage increases as the pedal is depressed. APP sensor 2 and sensor 3 signal voltage decreases as the pedal is depressed. The APP sensor signals are used by the PCM to monitor and make available one accelerator pedal percent PID.

The GM truck pedal introduced in 1999 was used through 2005. There is an adjustable pedal assembly but the APP sensor is the same. The 1999–2002 systems use all three of the APP signals while the 2003–2005 systems use only two of the three APP signals.

The GM truck pedal introduced in 1999 was used through 2005. There is an adjustable pedal assembly but the APP sensor is the same. The 1999–2002 systems use all three of the APP signals while the 2003–2005 systems use only two of the three APP signals.

This wiring diagram represents the 1999–2002 GM truck electronic throttle control system. This is the only GM truck system that uses the three APP sensors in the accelerator pedal. Later systems use two APP sensors.

This wiring diagram represents the 1999–2002 GM truck electronic throttle control system. This is the only GM truck system that uses the three APP sensors in the accelerator pedal. Later systems use two APP sensors.

This wiring diagram represents the 1999–2002 GM truck electronic throttle control system. This is the only GM truck system that uses the three APP sensors in the accelerator pedal. Later systems use two APP sensors.

This wiring diagram represents the 1999–2002 GM truck electronic throttle control system. This is the only GM truck system that uses the three APP sensors in the accelerator pedal. Later systems use two APP sensors.

Throttle Actuator Control Module: The 1999–2002 truck TAC module is specific to 1999–2002 trucks and must use a 1999–2002 truck PCM. The truck TAC module looks identical to the 1997–2004 Corvette TAC module, and even has the same harness connections, but carries a different GM part number and is not interchangeable with the Corvette.

This is the 1999–2002 GM truck TAC module. It looks identical to the 1997–2004 Corvette TAC module but it is not interchangeable with other electronic throttle systems.

This is the 1999–2002 GM truck TAC module. It looks identical to the 1997–2004 Corvette TAC module but it is not interchangeable with other electronic throttle systems.

2003–2004

In 2003, General Motors introduced a new Gen III truck throttle body, TAC module, and PCM. This new throttle body is not backward compatible with the 1999–2002 trucks. Always use matching equipment to ensure compatibility.

This wiring diagram represents the 2003–2004 GM Truck electronic throttle control system. This system uses only two of the three APP sensors. As compared to the 1999–2002 GM truck TAC module, the 5V reference and low reference for APP sensor 2 have been swapped. Although 2003–2004 GM trucks use only two of the three APP sensors, the 2003–2004 TAC-to-pedal wire harness contains the three wires for APP sensor 3. This is probably a carry-over from 1999–2002 GM stock.

This wiring diagram represents the 2003–2004 GM Truck electronic throttle control system. This system uses only two of the three APP sensors. As compared to the 1999–2002 GM truck TAC module, the 5V reference and low reference for APP sensor 2 have been swapped. Although 2003–2004 GM trucks use only two of the three APP sensors, the 2003–2004 TAC-to-pedal wire harness contains the three wires for APP sensor 3. This is probably a carry-over from 1999–2002 GM stock.

The GM truck PCM and TAC monitor values from the three accelerator position signals to identify proper operation of the accelerator pedal assembly. A DTC sets if an APP value exceeds one of GM’s predetermined threshold values. This chart reviews the allowable operating ranges for each APP sensor (see “APP Failure”) and the expected 0- and 100-percent voltage ranges for each APP sensor.

The GM truck PCM and TAC monitor values from the three accelerator position signals to identify proper operation of the accelerator pedal assembly. A DTC sets if an APP value exceeds one of GM’s predetermined threshold values. This chart reviews the allowable operating ranges for each APP sensor (see “APP Failure”) and the expected 0- and 100-percent voltage ranges for each APP sensor.

The GM truck PCM and TAC monitor values from the two throttle position signals to identify proper operation of the throttle body. A DTC sets if a TPS value exceeds one of GM’s predetermined threshold values. This chart reviews the allowable operating ranges for each TP sensor (see “TPS Failure”) and the expected 0-percent range and 100-percent limit voltages for each TP sensor.

The GM truck PCM and TAC monitor values from the two throttle position signals to identify proper operation of the throttle body. A DTC sets if a TPS value exceeds one of GM’s predetermined threshold values. This chart reviews the allowable operating ranges for each TP sensor (see “TPS Failure”) and the expected 0-percent range and 100-percent limit voltages for each TP sensor.

The GM truck PCM and TAC monitor values from two of the three accelerator position signals to identify proper operation of the accelerator pedal assembly. A DTC sets if an APP value exceeds one of GM’s predetermined threshold values. This chart reviews the allowable operating ranges for each APP sensor (see “APP Failure”) and the expected 0-percent range and 100-percent limit voltages for each APP sensor.

The GM truck PCM and TAC monitor values from two of the three accelerator position signals to identify proper operation of the accelerator pedal assembly. A DTC sets if an APP value exceeds one of GM’s predetermined threshold values. This chart reviews the allowable operating ranges for each APP sensor (see “APP Failure”) and the expected 0-percent range and 100-percent limit voltages for each APP sensor.

The 2003–2007 truck TAC modules are interchangeable. This TAC module uses the same wire harness connectors as 1999–2002 GM trucks, with an aluminum back plate and smooth plastic cover, but the housing looks very different.

The 2003–2007 truck TAC modules are interchangeable. This TAC module uses the same wire harness connectors as 1999–2002 GM trucks, with an aluminum back plate and smooth plastic cover, but the housing looks very different.

Throttle Body: The 2003 throttle body was used with Gen III trucks from 2003 to 2007. The truck throttle body is fitted with an internal TPS to monitor throttle blade angle and an internal motor, operated by the TAC module, to open and close the throttle blade. The throttle body contains two individual TP sensors with separate signal, low reference, and 5V circuits. The two TP signals are monitored by the TAC module. As the throttle blade is opened, both TP sensor 1 and TP sensor 2 signal voltages sweep toward 5V reference. These signals are used by the PCM to monitor and make available one throttle angle PID.

Pedal Assembly: The 2003–2004 truck accelerator pedal assembly is the same as used with 1999–2002 trucks. With an option for an adjustable pedal assembly, the APP sensor is the same. The TAC module uses only two of the three APP signals to determine absolute pedal position. A change from the 1999–2002 truck TAC system is that both APP sensor 1 and APP sensor 2 signal voltage increases as the pedal is depressed. APP sensor 3 is no longer used by the 2003–2007 truck TAC modules, but the 2003–2004 TAC-to-pedal harnesses contain the three wires once used for APP sensor 3 (as found in 1999–2002 truck TAC-to-pedal harnesses). The APP sensor signals are used by the PCM to monitor and make available one accelerator pedal percent PID.

This wiring diagram represents the 2005 GM truck electronic throttle control system. Just like the 2003–2004 GM truck system, only two of the three APP sensors are used. By 2005 you should not expect to see the unused three wires for APP sensor 3.

This wiring diagram represents the 2005 GM truck electronic throttle control system. Just like the 2003–2004 GM truck system, only two of the three APP sensors are used. By 2005 you should not expect to see the unused three wires for APP sensor 3.

This wiring diagram represents the 2006–2007 GM truck electronic throttle control system. As shown in this schematic, the introduction of a new accelerator pedal assembly means a different TAC-to-pedal wire harness.

This wiring diagram represents the 2006–2007 GM truck electronic throttle control system. As shown in this schematic, the introduction of a new accelerator pedal assembly means a different TAC-to-pedal wire harness.

The GM truck PCM and TAC monitor values from two accelerator position signals to identify proper operation of the accelerator pedal assembly. A DTC sets if an APP value exceeds one of GM’s predetermined threshold values. This chart reviews the allowable operating ranges for each APP sensor (see “APP Failure”) and the expected 0-percent range and 100-percent limit voltages for each APP sensor.

The GM truck PCM and TAC monitor values from two accelerator position signals to identify proper operation of the accelerator pedal assembly. A DTC sets if an APP value exceeds one of GM’s predetermined threshold values. This chart reviews the allowable operating ranges for each APP sensor (see “APP Failure”) and the expected 0-percent range and 100-percent limit voltages for each APP sensor.

Throttle Actuator Control Module: The 2003–2004 truck TAC modules are interchangeable with 2005–2007 truck TAC modules. With an aluminum back plate and smooth plastic housing, this truck TAC module has an appearance different from the 1999–2002 truck TAC modules. The harness connections at the TAC module are the same, but the 1999– 2002 truck engine wiring harnesses are not directly compatible with the 2003–2007 Gen III trucks.

2005

The 2005 truck electronic throttle system uses the same throttle body, TAC module, PCM, and accelerator pedal as the 2003–2004 trucks, but the non-use of APP sensor 3 shows itself with the removal of the three APP sensor 3 wires in the TAC to-pedal harness. The 2003–2005 TAC-to-pedal harnesses can be used interchangeably because APP sensor 3 is not used by the 2003–2007 truck TAC module.

2006–2007

The 2006–2007 Gen III truck electronic throttle system uses the same throttle body, TAC module, and PCM as the 2003–2005 trucks. The only change in 2006 was a new accelerator pedal assembly. All other electronic throttle system components are interchangeable with 2003–2005 trucks.

This accelerator pedal assembly is used with 2006–2007 GM trucks and is functionally interchangeable with the 2002–2005 system. A matching TAC-to-pedal wire harness is required.

This accelerator pedal assembly is used with 2006–2007 GM trucks and is functionally interchangeable with the 2002–2005 system. A matching TAC-to-pedal wire harness is required.

Pedal Assembly: Although smaller in size, the 2006–2007 truck accelerator pedal assembly is functionally the same as the 2003– 2005 assembly. Containing only the required two APP sensors, the harness connection on this pedal assembly uses only six wires. The 2003–2005 accelerator pedal assembly contains three APP sensors, but only two are used, leaving three connector cavities unused (as is found in 2005 truck TAC-to-pedal harnesses). The TAC module uses the two APP signals to determine absolute pedal position. Both APP sensor 1 and APP sensor 2 signal voltage increases as the pedal is depressed. The APP sensor signals are used by the PCM to monitor and make available one accelerator pedal percent PID.

 

EFI Connection 24x Throttle Body Assemblies

Bringing LS fuel management to early small- and big-block Chevrolet engines requires an electronic throttle body assembly that fits the early fuel injection intake manifolds. EFI Connection’s solution was to use the 1997–2004 LS1/LS6 Corvette throttle body, but within a new housing designed for TPI and LT1 intake manifolds.

Offered with twin 52-mm blades, twin 58-mm blades, or an oval mono blade, an electronic throttle body solution is available for any intake  manifold using the popular TPI/ LT1-type four-bolt pattern. All three throttle bodies are machined from a solid block of 6061 T6 heat-treated   aluminum. The throttle blade shaft is supported by sealed ball bearings for longevity and the throttle blades are CNC machined, rather than being stamped, for a precise fit. These CNC-manufactured throttle bodies are among the highest quality from the aftermarket.

EFI Connection’s lineup of electronic throttle bodies for TPI, LT1, and Ram Jet 502 are available in common sizes: 52 mm, 58 mm, and oval mono blade.

EFI Connection’s lineup of electronic throttle bodies for TPI, LT1, and Ram Jet 502 are available in common sizes: 52 mm, 58 mm, and oval mono blade.

This EFI Connection 58-mm electronic throttle body flows approximately 1,100 cfm  making it appropriate for engines making 480 to 600 hp.

This EFI Connection 58-mm electronic throttle body flows approximately 1,100 cfm making it appropriate for engines making 480 to 600 hp.

This 52-mm electronic throttle body is installed on a TPI engine. The TPI plenum was slightly ported to line up with the 52-mm throttle bore openings. Flowing approximately 920 cfm, this throttle body is adequate for engines making 325 to 480 hp.

This 52-mm electronic throttle body is installed on a TPI engine. The TPI plenum was slightly ported to line up with the 52-mm throttle bore openings. Flowing approximately 920 cfm, this throttle body is adequate for engines making 325 to 480 hp.

This Ram Jet 502 engine receives much more air with this mono blade electronic throttle body. With an LS1 Corvette- based electronic throttle system and PCM, this engine has much more to offer than it did with the bundled MEFI (marine electronic fuel injection) ECU and 48-mm cable throttle body. This mono-blade throttle body flows approximately 1,250 cfm and is a good choice for engines making more than 600 hp.

This Ram Jet 502 engine receives much more air with this mono blade electronic throttle body. With an LS1 Corvette- based electronic throttle system and PCM, this engine has much more to offer than it did with the bundled MEFI (marine electronic fuel injection) ECU and 48-mm cable throttle body. This mono-blade throttle body flows approximately 1,250 cfm and is a good choice for engines making more than 600 hp.

 

52-mm TPI/LT1 Throttle Body

EFI Connection’s 52-mm electronic throttle body is intended to be used on stock to mild small-block engines. With nearly 920 cfm of airflow, this throttle body is good for engines making 325 to 480 hp. Most intake manifolds with the dual-bore, TPI-type throttle openings require minor port matching for smooth airflow transition from the throttle body into the intake plenum.

58-mm TPI/LT1 Throttle Body

EFI Connection’s 58-mm electronic throttle body is intended to be used on mild to aggressive small- and big-block engines. With nearly 1,100 cfm of airflow, this throttle body is good for engines making 480 to 600 hp. This throttle body requires port matching for smooth airflow transition and throttle blade clearance into the intake plenum.

Mono Blade TPI/LT1 Throttle Body

EFI Connection’s mono blade electronic throttle body is intended to be used on maximum-effort small-and big-block engines. With nearly 1,250 cfm of airflow, this throttle body is good for engines making more than 600 hp. This throttle body require  port matching for smooth airflow transition and throttle blade clearance into the intake plenum.

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