Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) What Did You Do To Your Morgan Today?

Blew a fuse
After switching on heated seats, heater, heated windscreen and lights, BRUM came to a stop at the traffic lights. Lucky I was close enough for SWMBO to push me down slope to Maccies where I rang for roadside assistance. After a few tests, a couple of attempted bump starts, I reiterated what I had just done (switched lots of electric things on) so the breakdown chappie checked the fuses. The 30amp one had blown, not having a 30 he fixed one with wire which got me home.
Ive to get a new 30amp but does this mean I cant have everything on at once? Is this a usual morgan thing or does it sound like dodgy wiring somewhere?

Tut,tut! Strange that a breakdown guy doesn't carry a box of fuses. The problem could have been overload or it could have been an intermittent fault. But worse than that, using a bit of wire may have got you home, but it is a cowboy approach and presents a high risk of fire. The reason that fuses are encapsulated in a tube or casing is to contain the arcing when a fuse melts. A safer approach would have been to replace the fuse with a smaller one that was available with a caveat not to turn on unnecessary things like seats, etc.
Best thing now is to remove the fuse and attach a multimeter (set on amps ) in its place. Switch on each of the loads and note the current draw for each one then add them up to see total load. My guess is that the heated seats broke the camels back. If so , it may be necessary to provide them with a new separate fused supply.

I carry a box of fuses under the seat.... good for the peace of mind.
My retro-fit heated seat pads came with a relay and I wired a separate feed ... however when I checked the paperwork I was surprised at how little power they took ... only around three or four amps if I remember correctly.

Good advice from Deejay.

K

I think the blown 30 amp fuse would be the ignition switch one Scott, first in the eight position high current fuse block. It will do no harm to uprate that to 40 amp given that accessories are often added after factory build. This unless you find an obvious reason for fuse blowing other than combined current load.

BTW I have a current measuring device that clamps on individual cables. Far simpler and less invasive that using current measuring mode on multimeter which are often limited to 10 amps anyway. Note also that such tests will often be performed with engine off or at idle whereas battery volts and current drawn will be higher whilst driving with alternator providing charge current by up to two volts more.

Richard ... what clamp on ammeter do you use ? ... had one but lost it and think a replacement would be a good addition to my tool kit.

K

It's a Sealey MM405 K. They seem to have gone up a bit since I bought mine 12 years ago, at around the £100 mark now. Works on both AC and DC (which many cheaper don't) and up to 200 amps.

Cheers Richard ... will take a look.

K

Richard
Thank ou for the tip!
I just found out that there are even clamp multimeters with bluetooth function.

Thank you so much for taking time to reply like this

It was the first one, im getting fuse today so will look for a 40 amp but will also get it checked to see if there's a fault with any of the accessories. Thank you for taking time to reply and great advice.