412 / Beaufighter wiring & wiring diagram

[JLucy]

Following my recent post about Beaufighter spares, I'm pleased to say my car is back on the road. Now I'm working on a long list of minor problems, some of which relate to wiring.

I have had various 'issues' with the electrical components of the car over the years. One time I was nearly stranded at the BOC Concours at Brooklands when the car steadfastly refused to start. It turned out that the heavy currents passing through the ignition switch (look at the size of cables to it!) had caused it to fail. On another occasion I found that turning on the heated rear window caused the engine to cut out, which may also relate to the ignition switch. I fitted a new switch, but haven't retried the heated window. The indicators flash too slowly; there seems to be a volts drop on the way to the flasher unit, but I can't find where. The headlight main beam is intermittent; it worked fine for the MOT test, but has now failed again.

As far as I can see there is only one high-current cable leaving the battery positive, and it goes across the car to what I assume is the starter solenoid relay on the bulkhead. There a single heavy-ish, but not huge, brown wire heads back towards the fuses and probably to the ignition switch.

Can anyone point me to a wiring diagram for the Beaufighter? Or even better a workshop manual that included a wiring diagram?

James

[Kevin H]

Originally Posted by JLucy

Can anyone point me to a wiring diagram for the Beaufighter? Or even better a workshop manual that included a wiring diagram?

James

James,
A workshop manual does not exist. I've never seen a wiring diagram either, although I thought someone produced one for the 603 at some stage, which would be very similar.

If the Beaufighter wiring is anything like the 411 wiring then it leaves a bit to be desired, mainly in the form of relays! Ideally almost everything should be on a relay so that there is no significant current flowing through any switches.

Some of the other problems you describe could be earthing issues, which can create some very strange effects on car electrical circuits. Poor earthing can also cause damage because it usually results in current flowing through things it's not meant to flow through!

First of all I would check the point where the battery earth/negative connects to the body. Make sure it is a solid, clean connection. I would also consider running a chunky earth strap to the starter motor or at least the engine (this cured starting problems on my 411).

This might cure some of the issues. If not then you need to then look at each one in detail, paying close attention to the connections, at the accessory itself and the relay if it has one.

NB: I would advise against turning on the rear screen heater again until you have ascertained that it is connected correctly. I believe it is connected via a relay on the 411 so it is likely to be similar on the Beaufighter. It should also have it's own fuse, circa 35Amp.

Let us know how you get on.

Cheers,
Kevin

[Andy603]

James

I had similar problems with my 603, which being of similar vintage may have
bits in common.

The volts to the indicator flasher unit go through the hazard light switch.
All connections to this and the innards need to be clean.

The volts to my headlamps go through the switch, this had been arcing and
the casing had melted. I purchased a replacement switch from BCL, then
subsequently found one at an autojumble for a couple of quid. The main beam
on mine goes through a 26 amp relay by the fuse panel but the switch on the
indicator stalk arcs so may be badly pitted, I always use the footswitch.

Drawings are on the Bristol Owners Club website.


Andy

[browning l]

To assist further in locating these, look in the BOC site, in their Libary section, under 603s.

Here's the site: Member Area - Login

I have downloaded the complete 603 Owner's Manual, as well as a number of the wiring diagrams.

Good luck!

Lou B.

[Kevin H]

There's an online version of the owners manual on this site here . No paid up membership required

Unfortunately no wiring diagrams, but the electrical system could do with some modernisation anyway.

[browning l]

I guess I just assumed that nearly everyone seriously interested in Bristols would be a BOC member.

James, if you would like me to email you any wiring diagrams, just please let me know at mmm@maysvilleky.net, and I'll be more than happy to do so.

Here's a list of what is shown to be available:

Wiring diagrams (PDF thanks to Clive Foster)
Speed Control circuit: SVG/PDF
Headlamp circuits
Side, rear and dash lamps
Foglights & heater
Rear window & gauges
Electric Window Lifts
Boot lid, fuel filler & Sunshine Roof
Fans, horn, clock, lighters & aerial
Seat back adjustment & int. lamps including red warning lamps in door armrests
Wiper motor and wash/wipe: SVG/PDF
Flasher, Hazard, Stop & Reversing lamps and Battery condition indicator
Fuse layout: SVG/PDF
Air conditioning: SVG/PDF
Oil Pressure Unit, Carb Solenoid & electric choke: SVG/PDF
Ignition/starter switch: SVG/PDF/PNG
Alternator voltage control circuitry: SVG/PDF/PNG
Seat-belt drawings (thanks to Graham Bell)
Seat belt assembly
Long End assembly

Lou B.