Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Fuse Confusion

My horn stopped working so I embarked on a fault finding process to find the problem.

To cut a very long story short, I checked the fuse diagram and saw that Fuse 9 was the horn and radio. Radio still working so it can't be the fuse.

So move on and look for other issues. Horns worked when hot wired. Horn push continuity fine. Steering wheel earth contact continuity fine. Couldn't find any broken wires or loose connections.

What the heck????

Then I remembered that the radio is always live but the horn only works with ignition on so how can that use the same fuse.

Re-check the fuse diagram and spot the radio can also be covered by fuse number 17 which is permanently live for radio, courtesy light and others.

Pull number 9 fuse and low and behold the radio is still working.

So replace with a new 10 amp fuse and eureka the horn works.

The fuse diagram for my 2009 car is misleading or at least has a choice of 2 radio wiring options. One using fuse 9 and the other using fuse 17.

Anyway, problem solved but it just goes to show that Morgan fault finding is not always logical and straightforward

You can always be sure of uncertainty.

A trusted expert told me that yoy can never rely on the fuse diagram.

He also noted that a fuse sometimes develops a hairline crack and becomes intermittant, breaking down as it heats up.

I've experienced this, more than once. Testing the fuse out of the car shows a good fuse, as soon as it warms up it goes open circuit. I was advised that it is better to replace a suspect. fuse than to waste time trying to find out.

All car radio's require two fused circuits Bob, one permanently live (fuse 17) for memory. Even MMC accomodate for them

BTW the only error I have found in the 2006 -2014 Classics parts book concerns the fuse labelling in the fuse box depiction of the later chassis loom. Fuses numbered 1 - 10 are correct but in the left hand row they start with fuse 20 at the top when it should be 11 dropping to 20 at the bottom. Actual wire locations are correct.

IIRC someone developed a fuse that had a minute LED built in that somehow illuminated when the fuse blew, very helpful for finding faults in the dark or tight access

But my radio continued to work with fuse 9 pulled but would not work with fuse 17 pulled suggesting it is only wired via fuse 17.

Talking of LEDS the one on the dash on my 4/4 does not flash am i missing something is it supposed two?

Barry my 2011 4/4 the engine isolate LED in the dash does not flash. I am told that they were never connected up in the 4/4s. But should you ever need to count the flashes, (look in dim light), under the dash behind the glove box ( R/H drive car) & you should see a LED flashing away when engine switched off & key removed. R

Ivormog ... they do indeed make those ... as well as blade fuses with a little reset button on top for reconnecting when they blow.

I worked with a tech who had been a sparky somewhere with decent voltage DC equipment (possibly boats) his diagnostic tool was to spread his first two fingers and run them down the metal caps of the line of fuses ... the one that gave him a jolt was the blown one!! 🙂

K