Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 998 / 996 / 916 / 748 > Help! electrical problems

[rob holmes]

I have what appears to be a problem with the wiring that feeds the engine management fuses and relays that are under the seat.Basically whilst out yesterday my bike cut out and after checking all fuses found that the 20A fuse next to the ECU had blown,luckily i carry spare fuses and i replaced the fuse only for it to blow again after setting off. This happened several times until i ran out of fuses which then lead to me calling the AA. When the AA arrived (10 minutes by the way) he suggested that i may have a loose wire thats causing the fuse to blow or have a fault on my fuel pump, he messed about with the wiring but it still kept blowing fuses, then for some reason i tried it again and it worked. I managed to ride the bike home and then luckily as i rode into the garage the fuse went again! After changing it for the umpteenth time the bike started but cut out straight away again i went to change the fuse but it was ok!!! the relay marked N02 was now clicking, tried swapping with the relay next to it but that also clicked . Now i'm well and truly stumped, is it a faulty wire?, faulty fuel pump?, water ingress? any help or advice would be great.
Cheers Rob.

[rob holmes]

this is doing my head in now, just tried it again now and it appears to be working fine, you know what will happen though, i'll just set off out and it will stop again miles from anywhere!!! if anyone has had similiar problems as to what may be causing this please let me know.

Thanks
Rob

[weeksy2]

I had simillar back many years ago on my 95 plate 916, it was a headlight connector that kept blowing it with a bad earth. But realistically, it could be pretty much anything or everything..

[rob holmes]

Well the problem is still there i went out today and got half a mile before the fuse blew,new fuse fitted and just managed to get home as it blew again. spent most of afternoon checking all wiring and connections under the seat and around the bike but cannot find anything untoward. Has anyone got any suggestions as to what is causing the fuse to blow?

[DEMON]

Let me know your exact model mate, and ill have a look at the circuit diagram when i get in from work. (im in the us at the mo, so you may get an answer by the time you get up in the morning).
Dc circuits are prone to poor earths, so check your cables and earth returns to the frame.
Look for any wires which are discoloured, this is a sign of overheating.
When your bike was running, was it running normally, ie lights and all other functions ?

Does the bike start ok, no problems ? does your bike have an alarm, if so which one ?

any accessories fitted to the bike ? ie aftermarket indicators, digi gears, or anything else ? quick shifter.

Think back to when your fuse blew...what were you doing at the time on the bike ?

Any info will help

[DEMON]

according to the diagram i have here, the fuse you are talking about is under the rear section, on the cross bar, and should be a 15 A one...am I correct, as you say its 20A

[DEMON]

looking at the cct daig, this fuse protects the ecu and power relays, could be a faulty relay (one of the two right under your seat)
send me a pm with your contact tel no and ill ring you in the next 1/2 hour.

[DEMON]

We need to know which model bike you have, with which ecu..then we can be more specific...however check the following as a matter of course :-

1.All connectors, all earths for loose wires / poor connections.
2. All connections to sensors / fuel pump
3. check connector block to ecu
4. check power relay connectors

report back

[rob holmes]

thanks for the replys Demon, its a 99 748 Biposto, i have swapped around the relays with no effect. I have had a thought though, you mentioned about overheating, yesterday my mate noticed that the temperature gauge was between 180 and 200 but the fan did not come on. Could it be the fan is not working and when the bike reahes a certain temperature it blows the fuse? i'm getting the father in law round today he's a spark and i'll get him to have a look. Will keep you informed mate.

[DEMON]

ok, then check the fan thermostat for good function, you say that the fan does not cut in, so a simple test would be to allow the bike to run whilst on the stand and observe what happens, when it reaches the cut in temp.