Well, the relay would not know how to tell you, because if I failed it would stop at any time, not only slowly and with the clutch pedal treaded right? In addition, in case of failing with a march, what the engine would do to you is that it would stop \ "push \" even though you step on the accelerator.
Anyway I leave you a link of an Opel forum where people who know more than me can tell you something about it.
www.clubpel.org .
Greetings and hopefully it is not serious.