Im looking for the cable that controls the fuel pump relay in an rst s2 -87
ive been testing the cables on the fuel relay, the red and black wire got +12v brown one gor earthing, red/black goes to fuel pump i guess cause when i put in +12 the fuel pump runs, then there is the misterious cable in the middle its green and red, now whats this for, its nothing on it, and if i throw on +12 nothing happens and if i throw in earthing nothing happens.
what i know is that the relay is earth controlled right?
i ask cause im putting in a management that grounds the fuel pump output when it will go active, tried to study the wiring diagrams but dont find any clue =(

 

should have wiring diagrams with your new managment...chances are you'll scrap the relay the bosch system uses

 

yeah just that the only thing the new management needs from old loom is the fuel pump start and stop, the rest is stand alone

 

wire a new relay, that would be the simplest solution...have to do this when converting to Ford EFi cos its linked in with the injector relay, if theres no link with the injector loom, just use a Ford (yellow) relay, all my diagrams are on RSmania, you can find the diagram on Steve's RSbible site too tho

 

yeah thats what i did today =) ill see how this goes hehe

 

The relay is tachometric. It needs to see pulses from the negative side of the ignition coil. The green red is connected to the rev counter if I recall correctly. and then from there back to the ignition coil on a plain gren wire.