Classic cars forum & vehicle restoration.

Rootes75 · Posted: Tue Apr 30, 2013 3:08 pm Post subject: Lucas RF95 Blowing Fuses

I have a 1947 Hillman Minx that I have just got back on the road after some 5-6 years in the garage. The car starts/runs fine and all the electrics work, ie trafficators/horn/wipers/lights etc when on tickover. But as soon as the car is driven the fuse for the horn/trafficator blows Crying or Very sad

, but everything else still works. I am no expert on auto electrics but have worked through the earths (I would presume that these are fine as everything works on tickover?) so I am thinking it may have something to do with the contacts? Has anyone got any ideas?

peter scott · Joined: 18 Dec 2007 Posts: 7117 Location: Edinburgh

Hi Rootes,

Welcome to the forum.

The wiring for the horn and trafficators goes down the centre of the steering column and comes out at the front of the steering box. I suspect that you may have an intermittent short at the point of exit from the box.

Failing that you may have a short within the steering wheel hub, beneath the horn/trafficator switches.

To withdraw the switch assembly (manette) you need to release cable at the steering box then slacken the grub screws around the steering wheelhub and pull it towards you. The pipe that carries the cable is in two parts with the upper part slotted into the lower part so you need the slots to line up when reassembling. This pipe ensures that the horn and trafficator switches don't revolve with the steering wheel. The pipe/tube is anchored at the point where the wires exit at the front of the steering box.

Peter
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1939 SS Jaguar 2 1/2 litre saloon

47Jag · Posted: Tue Apr 30, 2013 5:05 pm Post subject:

It sounds like a cable has rubbed through it's unsulation and is shorting to the body /chassis. You should do an eyeball on the harness anywhere it comes in contact with chassis. Another thing you could do is separate the wires (if there is more than one) at the fusebox. This could give you a clue as to where to look.

Art

Rootes75 · Posted: Tue Apr 30, 2013 6:21 pm Post subject:

Thanks guys.

Funny you mention the steering column Peter, I have just recently had the whole lot apart as I have had to reduce the play in the steering. The whole stator tube ect was withdrawn and when re-fitted all new connectors from column wires to the main loom were fitted. What I shall do is go back through the connectors and look for any obvious signs of wear/rubing/shorting etc.

Rick · Site Admin Joined: 27 Apr 2005 Posts: 22438 Location: UK

I suppose if you disconnect/isolate any feeds in to the column, and you're able to take it for a spin without blowing a fuse, you've narrowed the search down considerably.

It'd be interesting to see the Minx sometime, welcome aboard.

RJ
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Rootes75 · Posted: Tue Apr 30, 2013 6:55 pm Post subject:

My thought though would be if it were a short or something like that would it not blow the fuse straight away? I can leave the car idling for 10 mins and it all works but as soon as I put my foot down to pull away it blow the fuse.

peter scott · Joined: 18 Dec 2007 Posts: 7117 Location: Edinburgh

I think Rick's suggestion is your best bet.

Wires can easily remain isolated until a little vibration or disturbance of the steering causes them to make contact and short.

Peter
_________________
http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

Penman · Joined: 23 Nov 2007 Posts: 4755 Location: Swindon, Wilts.

Rootes75 · Posted: Sat May 04, 2013 1:24 pm Post subject:

After working back through the wiring connections at the base of the steering column I found that one of the connectors from the horn back into the main loom was a little loose.

After replacing the crimp and tightening it up I fitted a new fuse and to my relief after a short trip out round town the fuse and all the electricas were still operating!

Thanks guy for all your suggestions & advise. I'm glad I didn't go down the route of stripping the voltage regulator!

47Jag · Posted: Sat May 04, 2013 4:29 pm Post subject:

The fuses are independant of the voltage regulator and are there to keep things compact and covenient.

Art

peter scott · Joined: 18 Dec 2007 Posts: 7117 Location: Edinburgh

Hi Rootes,

I'm sorry but I don't think a loose connection would blow your fuses unless the connector could also short to some other metalwork.

So you may have inadvertently sorted the problem just by moving the wires but I suspect that you haven't actually prevented a recurrence.

That said, I think you can probably assume that you don't need to touch your control box (voltage regulator etc).

Peter
_________________
http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

Rootes75 · Posted: Sun May 05, 2013 8:49 pm Post subject:

Thanks Peter.

The crimp that I found loose on one of the horn wires had worked itself so loose that a very small section, less that 5mm I'd say would touch back against the horn bracket. I presume that it only occured when the car vibrated a lot rather than tickover. Due to the compact nature of the wiring coming out of the end of the steering box it looks fairly easy that if a wire were loose it would touch something else at some point under mvoement/vibration.

We took it to a show about 15 miles away today and I can say that its all working fine now.

Its a shame, its all come about by a previous owners attempts at re-wiring. All wires were replaced by wire of one colour and many connections had no crimps or bullet connectors etc so many were broken or had worked themselves loose.

peter scott · Joined: 18 Dec 2007 Posts: 7117 Location: Edinburgh

Rootes75 · Posted: Wed Jun 19, 2013 1:41 pm Post subject:

After a month or two of running fine its gone and b****y done it again! Will have to investigate again. Embarassed