At the time Judith was built there was a requirement for new cars in the UK to have a dim-dip system. This was to ensure that when driving on side lights the dip beam of the headlights was also on but at a lower intensity than normal dip beam. Whilst a 2CV’s electrics are normally very simple, the dim-dip system was a bit tortuous requiring the addition of two relays, a diode and a resistor.
[Note that the colours of the wires can vary, the colours shown in the above diagram are the colours I found on Judith which differ slightly from the colours in the Haynes Manual for 1967-1990 A-series cars and from the wiring loom I used for my Burton.]
To restore the system to original operation both relays and the resistor need removing and the wires to pins one and five of relay one need connecting. Credit for this discovery goes to John Wood who first published it in 1995 in an article in the 2CVGB magazine.
A full fix for this would involve taking the relay wires back to the main wiring loom and finishing them off properly. This, however, will take a lot of time and require the kind of access given by taking off the wing – not really feasible at the moment.
Given the main thing to achieve is shorting pins one and five of relay one I put together a short jumper cable with two spade connectors. To err on the side of caution I used some 200A headlamp wire but, depending on the headlights you’ve got fitted, you should be able to get away with a lower rated wire.
The underside of the relay has the pins numbered and, if you clean it up and look really closely, the pins are also marked on the connector. For the avoidance of doubt, it’s worth triple checking you have pins 1 & 5 on the relay, pins 1 & 5 on the connector and the correctly coloured wires.
With both relays removed and this jumper cable in place in the block connector the entire dim-dip system is functionally deactivated. The full removal can come at a later date.