What does the TCS Off button do? - 2004 Honda Accord

TCS stands for Traction Control System.
The traction control system works in conjunction with your Antilock Brake System (ABS) and your Engine Control Module (ECM) or Powertrain Control Module (PCM) or Electronic Control Unit (ECU) (Note that ECM, ECU, and PCM all mean the computer that controls your engine, depending on make.)

Anyway, the traction control system can apply one or more of the brakes and control engine RPM in the event that a wheel slip has been detected by the traction control system.

Pushing the TCS button on most models will light a lamp in the instrument cluster that usually says "Trac Off" Pressing it a second time will turn this light back off.

When the "Trac Off" light is illuminated, the Traction Control System is disabled and will not work in the event of a wheel slip.

Also note that when the Traction Control System is working and a wheel slip is detected, The Traction Control Module will usually illuminate a light that says "Trac" as it is taking control of your brakes and engine. It can feel really strange when this occurs and some people think that their transmission is slipping or that their engine has a misfire problem.
The chances are that if it occurred on wet, slippery pavement, the Traction Control System may have just saved your life.

If this is happening on dry pavement and normal driving conditions (starting, stopping, or turning), there may be a problem with the system. "False Traction Control" can happen just like a bad wheel sensor causing "False Antilock Mode".

Also check your Owners Manual for more specific information pertaining to your particular vehicle.

Turns the Traction Control System off/on

It turns the traction control off.This feature is very useful in slippery conditions

It switches the traction control off, try it carefully and see the difference.