Replacing stock Ducati 748-916-996 relays with solid state type Ducati stock relays are basically just the ordinary automotive type in a waterproof housing. They suffer from wear & tear as they contain mechanical springs which weaken and contact points which arc & burn over time. They also have slip fit spade type terminals, which can give rise to poor contact & affect function. They also don t react well to vibration, which compounds the above shortcomings due to contact bounce. I had trouble more than once in the first year with the bike, coming to a standstill twice & a bad misfire another time, All due to relays/bad contacts so I decided to do something permanent about it. My bike has 3 main relays, these are 1/. the ignition relay, 2/. the fuel pump/ignition coil relay and 3/. the ecu relay. There are also the fan relay, the side stand relay and the headlight relays. The side stand relay & switch have already been removed from this bike & the headlight relays don t seem to give trouble so I replaced the 3 main ones which bring the bike to a standstill when they give trouble with solid state Mosfet type industrial grade ones. The original relays are rated at 30/40 amps, my new solid state ones are rated at 100 amps at 30 volts DC The job was fairly simple, remove the relays one at a time, cut the wires and connect them to the new solid state relays with screw down eye terminals then mount the whole relay in an enclosure for good measure. The relays & enclosures are held down by M4 x 16 stainless steel screws with nyloc nuts underneath and the eye terminals are neatly finished with dual wall (glue lined) heat shrink tube for extra security. The screw down ring terminals are a huge improvement on the flimsy spade terminals on the original relays. I chose to mount all three relays under the seat in the same position as the original fuel pump & ecu relays. This makes for a really neat & tidy installation and gets the yellow ignition relay away from engine heat and also water splash. To do this I had to extend the ignition relay wires to reach the new location under the seat in front of the ECU. For this I used 2 twin core red/black sheathed automotive cables from the local auto electrician. I simply cut off the original relay holder, soldered the new cables on, shrink wrapped the joints and ran the cables alongside the original harness to the underseat location. Being black they look original & part of the bike. At this point I realised the fan relay doesn t actually turn the fan on, but simply supplies power to the thermal switch as soon as the ignition switch is turned on. So it is really only there to take some load off the ignition relay. As the new relays are rated at 100amps/30volts the ignition relay is well capable of supplying the fan circuit as well, so it was a simple matter to supply fan power directly from there & get rid of the last mechanical relay on the engine side of things. The fan relay socket has 4 wires, two heavy purple ones which are the power cables and two thinner cables, one black the other blue/yellow which are the control cables. I cut the socket off, connected the purple power cables together, terminals 30 & 87 and shrink tubed the joint. The control cables terminals 85 & 86 just need insulating as they aren t used any more. The whole cable end was then shrink tubed and cable tied with the rest of the harness out of the way. Power needs to be supplied now to the fan fuse direct from the ignition relay instead of direct from the battery. This is simply done by changing the link wire to the fan fuse #2 on the back of the fuse block from fuse #1 to any of the others which are all linked and supplied from the ignition relay. I used #8 as it was the only one with just the one cable already going to it s spade terminal. I removed the fuse spade, opened the crimp and attached the fan fuse wire to the original one & re-crimped. I then relocated the flasher unit to under the fuse box to enable better access to the oil filler hole at service time without having to disturb any electrics. It is now simply held in place under the fuse box with self adhesive Velcro. So now there are no relays in the original position at all, they are all tucked up cosy under the seat away from heat & water spray and the engine is completely served by modern high amperage solid state ones.
FUEL PUMP RELAY REMOVED AND CABLES TERMINATED FOR MOSFET RELAY NEW FUEL PUMP RELAY IN POSITION ON CABLES
FUEL PUMP RELAY IN ENCLOSURE WITH LID ECU AND IGNITION RELAY ENCLOSURES WITH NEW CABLES TO IGNITION RELAY
MOSFET IGNITION RELAY SHOWING NEW CABLES FROM BATTERY AREA FITTED FINISHED JOB WITH RELAY COVERS FITTED
FUSE CABLE MOD TO REMOVE FAN RELAY & USE IGNITION RELAY FOR POWER FEED ORIGINAL RELAY LOCATION WITH FLASHER UNIT MOVED TO FUSE BOX THE OIL FILLER PLUG IS ACCESSIBLE NOW WITHOUT DISTURBING ANY ELECTRICS
ORIGINAL FAN WIRING DIAGRAM, CIRCUITS SHOWN IN GREEN MY MODIFIED FAN WIRING DIAGRAM USING THE 100AMP IGNITION RELAY TO SUPPLY POWER TO THE FAN CIRCUIT VIA FAN FUSE #2 The relays I used are part # SY4086 from ELECTUS DISTRIBUTION They cost me $34 each at trade price. www.electusdistribution.com.au david jones 2011