Also making a splash in 1997 was the Corvette's all-new Gen III LS1 engine. A completely new PCM was developed to control the new engine architecture. The '97 LS1 module was designed around a much faster Motorola 68000 series processor. The unit's memory was also cranked up, now with a whopping 512 kilobytes on board. The pumped-up processor and memory allowed for a single integrated computer board, responsible for both time and event related computation. The module remained identical for 1998 as well, and had a service code of 16238212. A clean sheet approach to engine control was applied for the LS1 as well. The General still used familiar algorithms, such as short and long term fuel trims, but the mapping took on new looks and the interaction became more sophisticated, capitalizing on the addition of a crank position sensor and coil-on-plug ignition. However, the LT1 individual cylinder fuel trims were gone.
In 1999, the LS1 PCM was re-designed again. The connectors look practically the same as those on '97-'98 PCMs, but the small-er body of the new '99 PCM made it clearly distinguish-able. Even though the connectors ap-pear the same, the PCMs are not inter-changeable and the pin-outs are vastly different. Just plug-ging a '99 PCM into an older harness can damage the PCM due to the wiring differences. Internally, the redesigned LS1 controller featured tighter packaged electronics, but still utilized the Motorola 68000 chip, albeit with a faster clock speed. The '99 PCM carried over unchanged for 2000, and the two share a service code of 09354896. From a operating standpoint, the big news for '99 was the extension of the MAF table range. The '99 peaked at 12,000 Hz, up from the '98 peak of 11,250 Hz, which was easily exceeded. The increase in recognized flow potential carried out in load tables as well, expanding the peak from 1.0 gram/cylinder in '98 to 1.2 gram/cylinder in '99. The extra range enabled tuning for big engines. The faster processor made chugging through the maps at high rates (aka high rpm) more efficient as well.
In 2001, the LS1 PCM was upgraded again with a faster version of the Motorola 68000 chip. Additionally, some of the internal memory was moved around, making re-flashed, retro-fit interchangeability with '99-'00 questionable. Externally, the PCM is indistinguishable from '99-'00 modules. The '01 architecture remained unchanged across platforms through 2002, and again for 2003 Vettes. The PCM used service code 12200411. From an operating standpoint, this PCM introduced various algorithm improvements and mapping expansions, such as the advanced spark control tables-i.e., modifiers based on ECT, IAT, and AFR.
 The 1997 Gen III LS1 controller...  The 1997 Gen III LS1 controller was a completely new design, sharing nothing more than the finned aluminum look with LT1 units. The new LS1 controller was actually slightly larger than the LT1 box it replaced and featured only two harness connectors,... |  ...albeit each individual...  ...albeit each individual LS1 connector was larger than two LT1 connectors. The new LS1 controller had a total of 160 terminals, bettering the LT1's 128 total terminals. The 'knock module' access panel was gone from the LS1 module as well. |  The 1999 Gen III controller...  The 1999 Gen III controller was practically a completely new design again, yet shared the same type connectors as its predecessor. But, to add confusion and risk of ill-fated interchanges, pinouts were totally re-arranged.... |