For years, I’ve been active in automotive forums, aiming to contribute to a community that has greatly benefited my career. I often address questions from enthusiasts, regardless of whether I personally align with their project directions. My goal is to offer helpful insights and avoid debates. If discussions become argumentative, I prefer to step back.
When it comes to custom engine wiring harnesses, particularly for LS swaps, my preference leans towards comprehensive integration, including Vehicle Speed Sensor (VSS), brake, clutch, and other crucial inputs. However, I recognize that some builders choose to omit certain inputs, and that’s entirely their prerogative. There are indeed applications, primarily off-road vehicles, where brake, clutch, VSS, and similar inputs might be excluded, and while these setups can function, achieving optimal performance can be more challenging.
The torque reduction mechanism linked to the Transmission Control Converter (TCC) brake input is essentially an abuse management feature. Fortunately, this can be easily tuned out of the Powertrain Control Module (PCM), presenting no significant obstacle.
The Toyota runaway throttle incident serves as a critical reminder of throttle monitoring importance. GM vehicles incorporate meticulous monitoring systems, and significant discrepancies in throttle behavior will trigger a Reduced Engine Power (REP) mode as a safety measure.
Reduced Power Mode can be initiated through various triggers. A notable variance between the expected and actual Accelerator Pedal Position (APP) sensor output can activate REP mode. Similarly, a substantial difference between the Mass Air Flow (MAF) sensor’s measured airflow and the calculated airflow based on speed density can also lead to REP mode.
Importantly, based on my review of GM service manual diagnostic procedures, the cruise control (TAC module) brake circuit does not play a role in triggering the Reduced Engine Power Mode diagnostic. This distinction is crucial when troubleshooting or designing an Ls Standalone Harness Obdii system.
