J.L. Classics

LED PROBLEM when fitted to Classic car Also see page Fitting LED lights

LED LIGHTS fitted to Classic cars can "create" unwanted problems and these could be any of the following :-
The Car battery goes flat. The ignition light remains on with the engine running. The indicators do not flash nor do the hazard warning lights. The instrument back light dimmer switch does not dim the back lights. The new bulbs do not light up and other odd items now do not work. The headlights throw an odd pattern.

The practice of replacing original filament type light bulbs for LED lights is becoming more common. If there is a safety or reliability benefit I see no reason why one should not. Simply taking out old bulbs and replacing them with LED units can create unexpected electrical problems for the following reasons.
1/Work is often done by owners who commonly believe they are simply replacing an old style bulb for a brighter modern bulb; this is not the case. You are changing a filament bulb which glows white hot for a diode which emits light. The "Diode" has different properties to a standard filament bulb. This can create a wide range of unwanted problems - read on.
2/The supplier of “said” LED replacement does not know the specific application that you intend to put their items too. They do not know the exact electrical configuration, or the polarity of your vehicle`s electrics. Nor is any consideration made for the type of reflector or lens into which the new LED "multi light" source unit is going into.
3/In many cases the supplier of the LED light does not even quote the specification of their own bulb.

LED stands for light emitting diode. The job of a “diode” is to control the flow of electricity both in amount and direction. In removing a light bulb and fitting a diode into your vehicle`s original electrical circuit you might well be creating all sorts of problems that you do not want (due to the properties of the diode).
For Example - a/ The flashing indicators might not flash – this may be because the indicator flasher unit requires more amperage than that which 2 LED units are drawing down (which is a very small amount compared with 2 conventional 21w bulbs ).
b/ The dash back lights no longer dim using the dimmer switch. This might be because the system was not designed for LED`s.
None of the new LED bulbs appear to work properly. That might be because of the polarity of your vehicle relative to the current flow for your LED`s is at odds.
c1/ The Battery charging warning light or ignition warning light (what ever you chose to call it) remains lit with the engine running. No other problems exist. This may be because your charging system is not working as it should. After a while the vehicle battery will go flat resulting in starting issues etc. Some electrical generators retain a magnetic memory and continue working for a while. Dependant upon the type of electrical generating system your car has will determine how long it takes for the battery to go flat.
c2/The battery upon my car no longer charges/ my battery is flat but everything else is fine. As c1/.
Below is a recent case history ----
I was asked to investigate several car charging systems all with similar problems. Simple issues, like my battery charges but the ignition warning light stays on or I have a bright ignition warning light but the battery keeps going flat. It appears that some owners have gone LED mad, buying entire set of LED`s for every bulb upon their vehicle from Ebay or similar. In replacing their ignition warning light with a light emitting DIODE, the electrical current that should be exciting the alternator into action, is virtually cut off. It is this reason that the alternator will not work. The resolve to both the charging system problems illustrated above was to remove the new LED and put back the original ignition warning light bulb. Some alternators will temporarily retain a magnetic memory. This enables them to produce power even though the warning light remains lit (be it the 2.5 amp or an LED). This is temporary and sooner rather than later, your alternator will stop working all together and your battery will go flat due to lack of charging. By putting back the original bulbs a permanent resolve was created to both these cars problems


In the U.K. it is “illegal” to use a Classic car with LED bulbs fitted which shine upon the road. However you are permitted to fit them within the car.
British Road Vehicle Lighting Regulations 1989 specifies the dates before which lamps and light sources do not have to be Type Approved (i.e. this refers to the date the lights where manufactured NOT the vehicle). However, all newly manufactured lamps and bulbs must comply with the current regulations (i.e. Type Approval), regardless of the age of vehicle to which they are fitted.
The MOT is a minimum safety standard that does not permit dismantling to be carried-out during the examination. It does not, generally, enforce Type Approval. The current standard required by the MOT in respect of pattern and performance of headlights is much lower for a Classic car than that for modern vehicles. A poor performance or pattern may not constitute a failed test.
Most LED bulbs are made up of many different LED light sources secured to one stem, all being fixed at different angles. The way an original headlight reflector and lens concentrates these different light sources will be completely different to the way a single source of light (from the original bulb) is projected forward. Although the fitting of an LED bulb appears to the driver as being an improvement, oncoming driver may experience a negative/dangerous effect.
Currently we have yet to see any LED head light bulbs which have genuine “Type Approval authorisation” for retrospective fitment to Classic cars. If you look carefully some bulb packaging has written in small print “for off road use only”. Secondly, some of the largest suppliers servicing the Classic car parts market have recently withdrawn their LED headlight bulbs from sale.
MY HEADLIGHTS ARE DIM SO WHAT CAN I DO. See section on Headlights.

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