Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Rewiring '74 +8

Currently rebuilding a '74 +8 on a new chassis with Rover 3.9 EFI V-8 mated to a SUPRA 5-speed steel g-box. Can anyone please provide a range of wiring diagrams, e.g. JPG files or Links, with particular emphasis on the Indicator Flasher and Hazard flasher areas.
Would appreciate any assistance. Regards John

Have you looked at gomog.com
Wiring diagram there for 1977-1982 +8 which may help?

You may have to pick and chose with wiring diagrams John given the non-original nature of your rebuild but what are available are here from GoMog site.

I've never needed a wiring diagram as long as the existing loom still conforms to the Lucas wiring colour codes!

Kind regards

Arwyn

Although this is a 1973 4/4 some of the wiring info may be helpful (eg the colour code):

https://morganrebuild.co.uk/

As you will have seen the wiring diagrams on the GoMog site jump seamlessly from 1969 -1973 to 1977.
This is compounded by the combined layout for 4/4s and +8s upto 1973 being different to the 4/4 only diagram for 1973 cars.
The essential difference between them ALL three being whether the hazard flasher relays themselves had 2 or 3 pins. (The 3rd pin being a direct output for the flasher warning light) and the pin outs/ internal switch path of the hazard switch itself.

The principle of the wiring being a switched ignition passes through the indicator relay to the indicator switch and once switched left or right completes the circuit and earths out via the corner bulbs. A thermal switch within the indicator relay doing the making and breaking.
In parallel to this, the hazard relay is fed by constant power, as the hazard switch is switched, it cuts the switched ignition feed to the indicator relay and joins the left and right hand side wires together, hence all 4 corners flashing. The hazard warning lamp being fed from either the hazard switch or the indicator relay’s 3rd pin.

SO, check what is actually on YOUR car - then pick a matching wiring diagram.

THEN understand that if the 1969 - 1973 combined layout is appropriate: the ‘pin outs/ internal switching’ of the Hazard Switch should be seen as an artist impression and not an actuality. Careful study will show that it’s not to be believed.

ADD to that: Lucas committed a major crime against electricity but shorting out the left hand side and right hand indicators through the single turn signal warning bulb.

- If you are replacing like with like it will work
- If you change to electronic indicator relays they will need earths
- If you change to LED bulbs, the units will probably get confused by Mr Lucas’s idea of earthing through a route to the opposite side of the car via the unlit indicator bulbs. A couple of diodes and separate earthing routes for indicator bulb can fix that.

Actually I thought that rather clever allowing a single direction indicator warning lamp to be used when either direction indication selected. The warning lamp being wired across left and right indicator feeds and the circuit return through the bulbs of the non-selected indicator circuit. Current flow through say a 3 watt warning bulb and the combined 42 watts of front and rear indicators. The significantly higher resistance of warning bulb allowed most of the battery volts across it with current flowing in one direction or other when a selection made. I believe it was common practice in British cars of the period allowing use of a two pin indicator flasher and no diodes.

Lucas and others got up to all sorts of inventive tricks during that period. Parking lights, still required in unlit areas, achieved by ignition off indicator selection to illuminate one side or the other. Driving lights provided by dip beam headlamp filaments in series etc. Earlier still a Lucas DB10 flasher relay box that allowed each stop light to double as flashing rear indicator when selected, and I believe fitted to some early Morgan's.

Richard .... indeed, back in the day when they really understood analogue electrickery ..... now it just gets switched by digits and they'll bung in yet another ECU for the odd details.



K