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Dim Dip Modules

Dim Dip In 1987 UK regulations were introduced that required a vehicle (which did not comply with UNECE Regulation R48) to be fitted with a dim dip device such that the headlamps were operated at between 10% and 20% of normal intensity when the side lights were on and the engine was running. The intention of the legislation was to improve the visibility of vehicles when driving in towns and cities were it was felt that the headlights were dazzling, and sidelights alone were not adequate.

In some cases the dim dip operation is acheived by placing a resistor in series with the supply to the headlamps. This article covers the alternative found on many Morgan vehicles where a dim dip relay is fitted. In this case the right hand headlamp is placed in series with the left hand headlamp, so each 12 volt bulb will have 6 volts across it, and therefor run at reduced brightness.

The relay unit is a small black, rectangular box that will be found behind the dashboard. Markings may say something like 133/21 version 1 MEH 0850 5170

When this relay fails you may lose the dim/dip function, or could lose the right hand headlamp, or lose main beam, or just end up with an intermittant fault.

Replacement relay units are difficult to find, the alternative is to rewire the headlights to remove the dim dip function, and maybe replace the headlamp units with units which have pilot bulbs fitted.

I have not found a wiring diagram or description of the relay unit, but by measurement and wire colour code it is possible to deduce the function of each connection. The result of this analysis is shown in the attached pdf.

Once the dim dip relay is removed the wires from the vehicles wiring harness can be connected as follows

Connect the black wire to the black/brown wire. The black wire is connected to ground, the black/brown wire is the 0 volts connection for the right hand headlamp unit. Here you are basically providing a ground connection for the right hand headlamp. Both of these wires have bullet connectors, so it is easy to connect them together.

There are two blue/white cables from the harness, on has a male blade connector, the other has a female blade connector, these should be connected together, this is easy to accomplish as they are mating connectors. Here you are connecting the main beam feed to the right hand headlamp.

The remaining wires ( brown, blue/red, white, red) need to be carefully secured out of the way, ensuring they cannot touch each other or any parts of the vehicle

You should now find that the headlamps work with dip and main beam. In sidelight position the wing mounted position lamps will be lit.

The next step is to purchase replacement headlamp units with pilot lamps. The Cibie H180 headlamp units have received good reports from Morgan owners. The pilot bulbs can be connected to the same wire that feeds power to the wing mounted position lamps.


High level stop lights

Modern 'classic' Morgans have aa additional brake light centrally mounted above the spare wheel.

When carrying luggage, it is easy for the central light to be obscured, which in some countries is an offence.

The advantages of an additional brake light can be obtained by using a standard LED array and mounting it under the luggage rack. It is still highly visible to following traffic, is above the legal minimum height, and is neatly tucked away out of harm's way.

A couple of simple brackets are all that is required.



Australian Plus 4 owner Neil Hurst has developed a neat low-cost option

LINK TO Morgans Owners Club of Australia to go in here.

Common Problems

Water In Lights

If you get water in your indicator lamps fit a new rubber seal and coat with silicone fluid, if that fails carefully drill a 5mm hole in the lens at the bottom to let the lens breathe.