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[grade7]

Hi
so suddenly my car stopped after 15meters and wont turn on anymore. Turn key and nothing happens...
I found out that fuse nr 4 was blown
after i replaced it and turned on ingnition the fuse blew again.
What could be the problem and what deviced run on that particular fuse?
Thanks

[minifreek]

80amp is a hell of a fuse to blow but Id suspect alternator to begin with....

[Bigron]

"minifreek", I agree that 80 Amps is a hell of a fuse to blow, but surely it can't be the lternator? The battery connects directly to the alternator and thence on to the starter motor - no fuses in the pathway.
That said, I don't have a clue as to which circuits the 80 Amp fuse protects, but somebody will know......

Ron.

[omega2018]

FV4 (80 amp) - Ignition switch (sorry that's all it says).

FV1 (80 amp) - ABS and traction control
FV2 (80 amp) - Main Engine Relay and glowplug timer (petrol won`t have FV2)
FV3 (30 amp) - Motronic Control Unit
FV4 (80 amp) - Ignition switch
FV5 (80 amp) - 1,6,7,10,20,25,27,29
FV6 (80 amp) - 5,12,17,24, 33 (air con)

[Mr Gav]

I`d have a look at the actual switch on the end of the barrel, I had one catch fire on a MKII Cavalier and when I went to the stealers they had them on the shelf behind the counter for easy access, seems they were prone to it in those days and the switches were the same through the range.

[Kevin Wood]

First thing to do is the find out in which position of the ignition switch the fusible link fails.

Install a new one, and select each position on the switch in turn until the fuse fails. This link feeds the supply to the switch, but clearly one of the circuits fed by the switch is shorting. Once we know in which position the fuse fails, we can help.

In fact, can you remember if the dashboard lights came on in the "ignition on" position, but everything went dead when you turned the key to start the car? Or had the fuse already died just turning it to the ignition position?

[Bigron]

I hope this isn't a silly suggestion....
If you replace that fuse by a headlamp bulb, maybe you can trace the faulty circuit without costing a fortune in fuses; it will allow you time to investigate safely?

Ron.

[grade7]

thanks for replies!
so i went to repairshop and turned out that oil leak from engine had short circuited the starter motor.... (not sure if thats logical but thats what they said)
so after 100€ repairbill the car is running again.

[biggriffin]

thanks for replies!
so i went to repairshop and turned out that oil leak from engine had short circuited the starter motor.... (not sure if thats logical but thats what they said)
so after 100€ repairbill the car is running again.

For oil to be going on to the starter I would check the breather system and cam cover gaskets.

[Kevin Wood]

A short circuit at the starter motor would indeed explain it, but caused by oil? More likely the insulation failed, but, I suppose, oil leaking on it over a long period would have done it no favours.

[Bigron]

If you ever get a definitivce answer to this one, please let me know! I still go back to what I wrote 4 days ago - how come that fuse blows if the feed to the starter motor is direct, NOT via any fuse whatsoever?

Ron.

[Kevin Wood]

The feed to the starter motor is direct. The feed to the solenoid which engages it is via the ignition switch, whose supply is protected by an 80A fuse.

[omega2018]

all this is very odd, yes i'd expect the feed to the starter to be unfused but then again i wouldn't expect an 80 amp fuse to a solenoid.  i'd guess the starter takes 100amp and the solenoid less than 10. I also wouldn't expect oil to short 12V.  don't try this but it probably wouldn't even short 220V, oil is not a good conductor.  and if oil is shorting your starter what happens when it's raining?  water is a much better conductor.  perhaps the oil burnt on leaving some carbon deposit?  carbon would short it.

[Bigron]

"mogmog", I am also a little bemused by this, not least of which by the size of that fuse. Allowing for a 50% working ration, the solenoid would draw at least 40 Amps? Phew!
Also, there would need to be a LOT of carbon in a 12 volt system to blow such a fuse.
If I had to guess (and we will never know as the OP has had it replaced), I would say that the oil, etc., had gummed up the starter to such an extent that it siezed and held the solenoid in engagement - or doesn't it work like that? If it does, would the stall current of the solenoid be sufficient to blow that grown-up fuse?

Ron.

[Andy89]

The ignition barrel runs a lot more stuff and fuses, than that one solenoid. (so probably has to be 80A to be able to cope with all that's running of it.)
The 80A fuse is not even there on early models (with the rest of the fuses in the engine bay)