Technical F30 30A fuse blowing on starting Ducato 250 2.3 mjet

[Saltpeter]

Hi, I had a breakdown. The engine just stopped while driving and all dash lights went out. The breakdown people tried to jump start it but no joy. When I got the camper home I found the main 350A? battery fuse and the 30 amp fuse F03 had blown. Replaced them, dash lights OK so tried to start but the 30A F03 fuse blew again. There was no noise from the starter relay. The main battery fuse is OK. Has anyone had a similar problem. I think that the starter motor has either jammed or has failed. Any ideas very welcome as at the moment the camper spends more time being repaired than being used!

 

[Communicator]

Hi, I had a breakdown. The engine just stopped while driving and all dash lights went out. The breakdown people tried to jump start it but no joy. When I got the camper home I found the main 350A? battery fuse and the 30 amp fuse F03 had blown. Replaced them, dash lights OK so tried to start but the 30A F03 fuse blew again. There was no noise from the starter relay. The main battery fuse is OK. Has anyone had a similar problem. I think that the starter motor has either jammed or has failed. Any ideas very welcome as at the moment the camper spends more time being repaired than being used!

I think that 150A is a more probable value for F70 which supplies the engine bay fusebox, and hence the ignition switch. As the fault occured while driving this would seem to exonerate the starter motor? Something of a conundrum, as fault reoccurred when energising starter. Am I missing something?

 

[Communicator]

Hi, I had a breakdown. The engine just stopped while driving and all dash lights went out. The breakdown people tried to jump start it but no joy. When I got the camper home I found the main 350A? battery fuse and the 30 amp fuse F03 had blown. Replaced them, dash lights OK so tried to start but the 30A F03 fuse blew again. There was no noise from the starter relay. The main battery fuse is OK. Has anyone had a similar problem. I think that the starter motor has either jammed or has failed. Any ideas very welcome as at the moment the camper spends more time being repaired than being used!

Further to post #2, I think that you should include the possibility of a wiring fault. Unless any evidence suggests otherwise you could start with the engine bay fusebox. These fuseboxes do not contain conventional wires, but have layers of folded metal strips. I have seen at least one report of such a box overheating, but to blow a 150A fuse requires a low resistance short circuit.

 

[Saltpeter]

Further to post #2, I think that you should include the possibility of a wiring fault. Unless any evidence suggests otherwise you could start with the engine bay fusebox. These fuseboxes do not contain conventional wires, but have layers of folded metal strips. I have seen at least one report of such a box overheating, but to blow a 150A fuse requires a low resistance short circuit.

Thanks for your help, What happened was strange, here is the sequence of events. After o/night stop the engine started as normal. No warning lights on.I needed to wipe the screen but strangely the wipers did not work. I set off driving and all was OK for a few minutes when suddenly the engine stopped. This has happened before, reason never diagnosed, but normally it would restart after a couple of minutes wait and continue as normal. This time when I tried to re-start everything was dead including the instrument panel lights. The breakdown people arrived (not mechanics) and they tried to re-start using a big jump starter but all remained dead. When I got home I started to check and the main battery fuse CAL5 and the ignition switch supply fuse FO3 30A was also blown. The CAL 5 fuse is the main battery / starter protection fuse and has a very high amperage. I think 700-1200A /32V according to the internet. . As you say this would need a dead short OR a faulty/jammed starter motor to blow? When I replaced this fuse and the F30 fuse everthing came on as usual and wipers, lights, indicators etc worked but when tried to start the engine again the CAL 5 did not blow but the F30 did. The thing I find hard to understand is why the CAL 5 fuse blew. Do you think this could this have been caused when they tried to re-start with the big jump starter? Now I have to find the issue, I have got some new F30 fuses but need to find the cause before replacing it again.

 

[Communicator]

Thanks for your help, What happened was strange, here is the sequence of events. After o/night stop the engine started as normal. No warning lights on.I needed to wipe the screen but strangely the wipers did not work. I set off driving and all was OK for a few minutes when suddenly the engine stopped. This has happened before, reason never diagnosed, but normally it would restart after a couple of minutes wait and continue as normal. This time when I tried to re-start everything was dead including the instrument panel lights. The breakdown people arrived (not mechanics) and they tried to re-start using a big jump starter but all remained dead. When I got home I started to check and the main battery fuse CAL5 and the ignition switch supply fuse FO3 30A was also blown. The CAL 5 fuse is the main battery / starter protection fuse and has a very high amperage. I think 700-1200A /32V according to the internet. . As you say this would need a dead short OR a faulty/jammed starter motor to blow? When I replaced this fuse and the F30 fuse everthing came on as usual and wipers, lights, indicators etc worked but when tried to start the engine again the CAL 5 did not blow but the F30 did. The thing I find hard to understand is why the CAL 5 fuse blew. Do you think this could this have been caused when they tried to re-start with the big jump starter? Now I have to find the issue, I have got some new F30 fuses but need to find the cause before replacing it again.

I have a memory of a previous similar incident, perhaps that was yours?
eLearn diagrams for the x250 show a CAL4 fuse, rather than the CAL5 that you mention. This raises the question as to it being previously replaced.
Perhaps worth keeping in mind that the CAL fuse also protects the alternator and associated wiring.
If the starter is jammed, or there is an earth fault then it is possible that the CAL5 fuse was blown by jump start attempts, but why did the engine stop while driving. If you postulate an intermittent fault in wiring protected by F03 (ignition switch) then that is possible.

Why did F03 blow when you attempted to start the engine? I have a niggling thought that the eLearn diagrams may be over simplified in that they only show one winding on the starter solenoid. Certainly starter solenoids used to have two windings. A high current operating winding, and a lower current holding winding. The high current winding was earthed via the starter motor and shorted out when the solenoid contacts closed. For an illustration see attached x230 diagram. If solenoid does not close the main contacts, then it may be that F03 cannot carry the maintained higher current? I do not know for certain.
I am still struggling to link the failure while driving on several occasions, with F03 blowing when subsequently attempting to start. I keep thinking wiring fault. If for instance the main starter cable (including alternator and connecting cable) shorted to earth briefly, then this could perhaps drop the voltage sufficiently to upset the engine control unit?
I am sorry but I do not seem to be able to do other than offer suggestions.

 

[Saltpeter]

I have a memory of a previous similar incident, perhaps that was yours?
eLearn diagrams for the x250 show a CAL4 fuse, rather than the CAL5 that you mention. This raises the question as to it being previously replaced.
Perhaps worth keeping in mind that the CAL fuse also protects the alternator and associated wiring.
If the starter is jammed, or there is an earth fault then it is possible that the CAL5 fuse was blown by jump start attempts, but why did the engine stop while driving. If you postulate an intermittent fault in wiring protected by F03 (ignition switch) then that is possible.

Why did F03 blow when you attempted to start the engine? I have a niggling thought that the eLearn diagrams may be over simplified in that they only show one winding on the starter solenoid. Certainly starter solenoids used to have two windings. A high current operating winding, and a lower current holding winding. The high current winding was earthed via the starter motor and shorted out when the solenoid contacts closed. For an illustration see attached x230 diagram. If solenoid does not close the main contacts, then it may be that F03 cannot carry the maintained higher current? I do not know for certain.
I am still struggling to link the failure while driving on several occasions, with F03 blowing when subsequently attempting to start. I keep thinking wiring fault. If for instance the main starter cable (including alternator and connecting cable) shorted to earth briefly, then this could perhaps drop the voltage sufficiently to upset the engine control unit?
I am sorry but I do not seem to be able to do other than offer suggestions.

Thanks, I think the best plan is to check the starter / solenoid assembly. A jammed or faulty starter motor could be the problem.There is no noise when the starter is switched on, no clicking. Hard to figure out what could be causing the fuse to blow. The garage can check the wiring cct. at the same time.