Installing DRLs in replacement H4 Halogen MGBGTV8 headlamps

Here we consider the two options for retrofitting DRLs to a classic car like an MGBGTV8 and Chris Bound describes how he installed them.

There has been considerable interest recently in adding Daytime Running Lights (DRLs) to classic cars like the MGB and derivatives, mainly in response to concerns about the relative visibility of such a small car when alongside larger modern vehicles many of which now have bright DRLs as standard equipment.

See details of the replacement 7" H4 headlamp unit and parts for the 2-adjuster unit. More

See a copy of the full article covered by this webpage.


Replacement 7" H4 Halogen headlamp unit for a 2-adjuster back shell

Wiring diagram with the relay to automatically cut off the DRLs when the headlights are turned on.

MGBGTV8 with DRL bulbs fitted in the sidelight fitting of a pair of replacement rubber bumper H4 headlamp units

Chris Bound is carrying out an MGBGTV8 Conversion and has added Daytime Running Lights (DRLs) as an upgrade to his headlights. Here Chris describes how he installed them.
There has been considerable interest recently in adding DRLs to the MGB and derivatives like the MGBGTV8, mainly in response to concerns about the relative visibility of such a small car when alongside larger modern vehicles most of which now have bright DRLs as standard equipment.

Dedicated daytime running lights
DRLs are purpose-made, low-wattage lights that can be fitted to a vehicle and used during the day to improve the visibility of a vehicle to other drivers as well as pedestrians, cyclists and other road users. They do not need to be operated manually as they automatically activate when the engine is started and turn off when the engine stops or
when headlights are switched on at night. DRLs are necessarily bright to ensure they are visible in the daytime but not so bright that they will dazzle others. However they are too bright for night time use and are not intended to illuminate the road in the dark. If used at night they will cause dazzle and discomfort to others road users and so drivers should always switch to their position lamps or headlamps at night. Evidence supporting DRLs comes from research which has shown that DRLs are likely to reduce multiple vehicle daytime accidents and fatalities by up to 6% once all vehicles are equipped.

Retro-fitting DRLs
There is no requirement to retrofit DRLs on vehicles not fitted with them as standard. If you decide to retrofit DRLs you should ensure they have been approved to the correct European legislation standards. This can be confirmed by checking that the approval mark embossed on the lamp contains the letters "RL". Ideally retrofitted DRLs should be installed such that they activate automatically when the engine starts and switch off when headlamps are turned on. If this is not the case then you must ensure that you manually turn DRLs off at night as they will cause dazzle and discomfort to others if used in low ambient lighting conditions.

What are the DRL options for an MGBGTV8?
Several options for DRLs have been identified by members of the V8 Register of which the most popular appear to be:

Adding LED strips below the bumper.

Fitting replacement H4 headlamp units which incorporate a pilot light fitting which can be used for the DRL bulbs. Although these headlamp units were installed on rubber-bumper cars in order to provide side or parking lights, they
are easy to fit to earlier chrome bumper cars. Once installed, they can be fitted with a bright LED bulb in the pilot light fitting which can then be wired up as a DRL. The original combined sidelight and indicator unit on a chrome bumper car remains unaltered. The DRL installation using a rubber bumper replacement H4 Halogen headlamp unit can only be fitted to a chrome bumper MGBGTV8 because otherwise where would you have the sidelight for a rubber bumper model as the lamp in the rubber bumper is only an orange indicator lens and not a combined sidelight and indicator?

Need for a relay to operate the DRLs
The operating requirements for DRLs are that they come on automatically whenever the ignition is on and that they turn off when the side lights or headlights are turned on. This can be achieved quite easily using a 5-pin changeover relay such as the one shown above.

Wiring details
For details explaining how the 5 pins on the relay (see diagram above) are usually laid out and numbered together with the wiring the DRLs via the original standard fuse box on the offside inner wing are described in the full article.
See V8NOTE573

Where to get relays and other materials?
Chris Bound adds "I usually buy electrical stuff for the car from Auto Electric Supplies Ltd (or AES for short) and always keep a printed copy of their catalogue to hand. Links to their website and the relay I used (Item 140206 are:
www.autoelectricsupplies.co.uk and here: www.autoelectricsupplies.co.uk/product/174/category/36
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