Recently, I’ve been trying to convert most of the lamps on my old Mk4 Fiesta over to LEDs. There are several motivations for this:
- A better quality of light.
- Reduced chance of a failed bulb attracting the attention of the Old Bill.
- Reduced possibility of a flat battery if I manage to leave the lights on.
I have exclusively used products from Classic Car LEDs with whom I have no connections other than as a satisfied customer. They appear to make quality products and provide a good level of customer support. I was also concerned by many adverts online suggesting that their LED lamps were much brighter than the originals and found notes from some customers that they had failed MOTs or even been pulled over for having tail lights which were too bright. Classic Car LEDs seem to take a more measured approach here.
On a related point, the tail lights on the Fiesta are not a common size and few other suppliers seemed to make LEDs which would fit.
About a year ago I replaced the tail and side lights as an experiment. It seemed to go well. The lamps were easy to fit and produced a good light. The side lights were particularly pleasing as they were much more effective than the originals. Clearly, no-one is going to complain that your sidelights are too bright as they are still very much dimmer than the headlights.
The only trouble I had was that one of the sidelight lamps fell out twice. I decided that it must be a tiny bit thinner than the original bulb. Concluding that the LED was likely to outlast the vehicle, I just glued it in.
Flushed with this success, I decided to replace all of the other lamps – including interior – except for the front and rear fog, reversing and main beam. I skipped the main beam as it would be expensive and the others are used to rarely that they didn’t seem worth it. I also haven’t replaced any of the instrument lamps but may do so in the future.
Generally, this process went well, but there were a few issues of which the first one was “polarity”.
Cars are either “negative earth” or “positive earth” configuration and this described which pole of the battery is connected to the chassis. All modern cars – including my Fiesta – are negative earth (NE), but some vintage and classic cars are positive earth (PE).
Many car bulbs are bayonet fittings and the outer of the bayonet naturally connects to the chassis. On an NE vehicle the centre contact of the bulb is therefore positive and the outer negative with the opposite on a PE vehicle. For a bulb with a filament this makes no difference, but LEDs only work one way round.
To allow for this, Classic Car LEDs sell many of their lamps in two varieties for NE and PE vehicles although some have internal rectifiers to allow them to be used with either. Some others (such as my sidelight lamps) can be inserted either way round in their sockets so if they don’t work you take them out and turn them round.
The Mk4 Fiesta however is a complete nightmare. The wiring is such that some bulb holders are NE whilst others are PE. In the rear light clusters, there is actually a mixture within each cluster.
Classic Car LEDs ‘helpfully’ changed the polarity of the tail lamps in my first order assuming that they must have to be NE on such a vehicle. Fortunately they were the ones which work with either so it didn’t matter. I now make a point of being very clear that I have checked the polarity.
For the benefit of others who may attempt a similar upgrade, the PE lamps are: rear indicator, brake, tail and map.
I have been careful to match the LED colour to the filter colour, so for example the tail and stop LEDs are real red LEDs rather than having a white LED and relying on the plastic filter. As Classic Car LEDs point out, this produces and deeper and more satisfying colour of light.
With most lamps now installed, things have gone reasonably well with the exception of the indicators and the dipped beam which I will blog about later.
