ASR Diagnostics
 

I found this info today on a Mercedes technical bulletin and though I'd share it.


This could help expedite an ASR diagnosis: If the ASR light comes on while driving and stays on until the ignition is turned off, but the accelerator pedal feels and functions normally, you've most probably found a failed pressure pump
(either return/pressure or the charging pump), a bad pressure reservoir or a leak in the hydraulic circuits. If the ASR light comes on under the same circumstances,
but the accelerator pedal is harder to push and the engine power output
is noticeably reduced, the problem is more likely in the electronic accelerator system rather than in ASR.