Roverdrive Posted March 11, 2017 Share Posted March 11, 2017 Morning all I am trying to trace an electrical gremlin on my 110. There is a battery isolation switch which is turned off when the vehicle is parked, and across this is a fused link to keep alive the radio memory and allow side lights parking at night. The problem is that this fuse has started blowing for no apparent reason. I swapped out the 10 amp fuse for a 30 amp with the same result. The concern is that when diving along with the isolator closed, there could be an intermittent short circuit. The engine bay fuses are all intact, and nothing blows in the cabin fuse box, so I am guessing it must be one of the live feeds to the fuse box somewhere. I have tried putting a lamp across the fuse terminals and shaking e wiring about, including behind the fuse box, and it does not light. Putting the side lights on does bring the test lamp on so I know it works. Does anyone have any experience on known chafing points in the loom to check? Must be live with the ignition off. many thanks Mike Quote Link to comment Share on other sites More sharing options...
mmgemini Posted March 11, 2017 Share Posted March 11, 2017 an isolation switch or an FIA battery master switch Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted March 11, 2017 Author Share Posted March 11, 2017 It is a key operated. Battery isolation switch Quote Link to comment Share on other sites More sharing options...
ballcock Posted March 11, 2017 Share Posted March 11, 2017 Does it only happen when it has been raining? Or has someone tried borrowing it without you knowing? Quote Link to comment Share on other sites More sharing options...
western Posted March 11, 2017 Share Posted March 11, 2017 4 hours ago, Roverdrive said: It is a key operated. Battery isolation switch like this one http://www.12voltplanet.co.uk/battery-isolator-switch-removeable-key-with-ignition-isolation.html this one will allow power to items like radio memory/clock or this one http://www.12voltplanet.co.uk/battery-isolator-switch-removeable-key.html this one switches everything off Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted March 11, 2017 Author Share Posted March 11, 2017 Ralph, it is one of these, or something similar. I know mine is rated for 400 A, http://www.auto-electrical-supplies.co.uk/durite_0-605-20_battery_isolator_switch_with_removable_key_in_the_on_or_off_position?gclid=CN2Yot2nz9ICFVYz0wodw0wHSg Ballcock, there seems to be no rhyme or reason to it, which makes it doubly frustrating! It can go a couple of months with no problem, and then every day blow a fuse. It blew last night as I parked up. No lights on everything off, and turned the isolator off. Within 30 seconds the fuse had blown ( I was fitting the extra security devices etc!) I went back to it this morning, and fitted the test lamp straight away and the lamp did not light. I have since replaced the fuse, and it has not blown - yet! 1 Quote Link to comment Share on other sites More sharing options...
pete3000 Posted March 11, 2017 Share Posted March 11, 2017 You haven't got any rad fans or similar that can run after shut off? Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted March 11, 2017 Author Share Posted March 11, 2017 Pete No nothing like that. From the wiring diagram, I could change out the under bonnet fuses for something below 30 amp, and disconnect the heat plugs, and see if I can get something downstream of the fuse across the isolator to blow. At least that should narrow things down a bit. Quote Link to comment Share on other sites More sharing options...
pete3000 Posted March 12, 2017 Share Posted March 12, 2017 If it does it after you have ign off, I'd look at the brown/purple feeds first. Batt side of fuses or unfused feeds. May be teaching you to suck eggs but have a look behind dash and console particulalry in centre of dash where wiring drops below the heater box to fusebox. Also headlight switch wiring is another suspect area going from live brown. Clock feeds behind speedo should be protected by fuse nut not always. Unplug rear loom section carrying the purple for the caravan socket. Glow plug timer relay on engine comp bulkhead? has brown live feed. Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted March 12, 2017 Author Share Posted March 12, 2017 Cheers Pete from my drawing the purple wire to he caravan socket is fused? i have had the fuse box out to check the wires behind, and given them a good rattle around with the test lamp in place, but found nothing. Dashboard is next. I was thinking of disconnecting the heater plug harness, as it isn't needed at this time of year anyway, so that would rule that out. I have checked the feed to the plugs in case the relay had stuck, but it is ok. Will have another look at the headlight switch. thanks for the suggestions. Quote Link to comment Share on other sites More sharing options...
ballcock Posted March 12, 2017 Share Posted March 12, 2017 Could the alternator be shorting when stopping in a particular position? Quote Link to comment Share on other sites More sharing options...
Snagger Posted March 13, 2017 Share Posted March 13, 2017 I'd be most suspicious of the wiring to the rear number plate lamp where it goes through the body panels. The side lights are unlikely to short, but checking the condition of the wiring and grommets at the back end of the tub where the wires come up from the chassis to the inside would be prudent. WHat fuse rating are you using, and are you sure it's not the fuse loop itself shorting against the panel it's mounted on? Quote Link to comment Share on other sites More sharing options...
pete3000 Posted March 13, 2017 Share Posted March 13, 2017 Also the big thick red cable from battery over outrigger to starter solenoid, could be chafing, especially if you've had any work done on BH or footwell. Quote Link to comment Share on other sites More sharing options...
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