Hello All,

I would ike to install a starter relay kill switch into my new scala.  I have now discovered that tyere are apparantly 2 starter relais in the engine bay fuse box. (se attached image).

Does soembody here know a bit more about the function of these 2 relais?    Why 2 ?   And what happens if I just disable one of them?   

 

I have a modified 646 relay where the actuation circuit is interrupted and is routed to an external switch which I can hide somewhere in the interior of the car.    

I could easy modify a second one but I am not sure at this stage if this is needed. 

Anybody have access to the wiring diagram of teh scala and  send me the relevant circuit?    

Further to my initial post, I wanted to add that my Scala is a DSG automatic and I have found some information on another web site that there might be two starter relais in serie. the firts relay is actuated by the starter switch and the second relay is connected to a clutch sensor.  So, only when the clutch is pressed or desingaged will the second relay be closed and to allow the signal to pass through to the starter moror (it could also be the other way around but it would result in the same scenario) .     

Could this be the case here and if so, would it matter which relay has the kill switch installed?    

Edited 20 February, 20251 yr by rrjmaier

My concerns here would be whether interfering with relays would have a knock-on effect to any other aspect of the car - particularly stop/start - and whether it would invalidate the warranty. Even moreso if done as a DIY project. 

10 hours ago, MikeHorsham said:

My concerns here would be whether interfering with relays would have a knock-on effect to any other aspect of the car - particularly stop/start - and whether it would invalidate the warranty. Even moreso if done as a DIY project. 

Mike, 

I do understand your concern but that is the reason why I am aiming for a relay.  This is a passive component which is plugged into a socket and has no other interface connections with the rest of the car.   It is actually a rather ancient technology and as such nearly bomb proof.   The circuit for the starter motor should be very straight forward and no ecu interface in the connections. 

The modification I have done to the relay (and others have done too) is to interrupt the connection between the input pin for relay actuation coil and the coil itself and have routed this to a manual switch which i can hide in the car.   When the switch is off, the relay simply will not be able to actuate.   When I want to start and drive then I flip the switch and it remains on during driving, thus also allowing start stop and any other function.   

The one issue I have is that I never had a car with two relais (or a DSG gearbox)  hence I am going at this at a slow pace, but I dont think that there is any real issue in regards to warranty or otherwise.   Simply pull the modified relay and replace it with the standard one.