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.
