MG5 Light festoon mod guide

[Seaniepie]

I wanted to mod my car with a small LED wire (1 meter) to go at the front of the hood. Did some testing with the wiring and found out the following. I post here in case some find it useful.

Car Open, Power Off
Bl/wh - 11V
Rd/wh - 12V
LgtBl - .03
DkBl - 0.6
Rd/gy 0.4

Position 1 (Amber led on start button)
Bl/wh - 0
Rd/wh - 0
LgtBl - 0.03
DkBl - 0.6
Rd/gy 0.08

Position 2 (Green led on start button) - HL & Auto on (at night)
Bl/wh - 11V
Rd/wh - 12V
LgtBl - 12V
DkBl - 12Ve
Rd/gy - 12

Side Only (on stem)
Bl/wh - 11V
Rd/wh - 12V
LgtBl - 0.4V
DkBl - 0.5V
Rd/gy - 12V

Auto off
Bl/wh - 11V
Rd/wh - 12V
LgtBl - 12V
DkBl - 0.6
Rd/gy 0.3

I connected my LED wire to the Dark Blue cable and one of the blacks. This means it only comes on when the headlights are on which is perfect. The driver for the LED works best at 11.6V rather than >12V so I feed it first to a small voltage limiter. These led wires are just 0.3A (3.6W) so they barely use anything. Looks cool though.

 

[Ozzie1989]

Does look cool, but a heads up l, assuming you're in the UK as it's RHD it does contravene road vehicle lighting regulations.

7. Front facing position lamp colour:
White or, if incorporated in a headlamp which is capable of emitting only a yellow light, yellow

It's a bit like the LED headlight debate though, it's up to the driver to determine the risk which in this case is probably low and if stopped or failed MOT, worse is you'd be ask to disconnect it

 

[Alb]

It looks good and well done for the investigative effort
You do realise of course that this will attract the attention of road traffic police?

 

[Kithmo]

You just need to get it to pulsate like Knight rider. now.

 

[Seaniepie]

Thanks for the heads up. I’ve removed it now. I was being a child. Fun while it lasted. There’d be small chance of insurance liking it too it seems. Best not to play with it.

 

[biffo]

I wanted to mod my car with a small LED wire (1 meter) to go at the front of the hood. Did some testing with the wiring and found out the following. I post here in case some find it useful.

Car Open, Power Off
Bl/wh - 11V
Rd/wh - 12V
LgtBl - .03
DkBl - 0.6
Rd/gy 0.4

Position 1 (Amber led on start button)
Bl/wh - 0
Rd/wh - 0
LgtBl - 0.03
DkBl - 0.6
Rd/gy 0.08

Position 2 (Green led on start button) - HL & Auto on (at night)
Bl/wh - 11V
Rd/wh - 12V
LgtBl - 12V
DkBl - 12Ve
Rd/gy - 12

Side Only (on stem)
Bl/wh - 11V
Rd/wh - 12V
LgtBl - 0.4V
DkBl - 0.5V
Rd/gy - 12V

Auto off
Bl/wh - 11V
Rd/wh - 12V
LgtBl - 12V
DkBl - 0.6
Rd/gy 0.3

I connected my LED wire to the Dark Blue cable and one of the blacks. This means it only comes on when the headlights are on which is perfect. The driver for the LED works best at 11.6V rather than >12V so I feed it first to a small voltage limiter. These led wires are just 0.3A (3.6W) so they barely use anything. Looks cool though.

Trying to figure out which wires are powered when DRL are on only - and do the DRL dim when headlights are on? Looks like sidelights (are these the same as DRL) are powered by the Red/Grey wire - maybe!! Or is this the Light Blue?

Just curious which wire would be best to power bottom driving/fog lights if looking to wire them as additional DRLs

 

[Seaniepie]

My personal recommendation is:
For DRL extension, Light Blue. However, DRL MUST be dimmable or extensions permanently run at a lower brightness than existing DLRs at ‘their’ lowest brightness.

For Fogs, Dark Blue (as these can only run when HL are on. Make sure it is switched.
Also make sure that any lights you add are approved and certified for use on cars in the UK or EU as relevant. If they are not certified it is an immediate MOT failure.
Adding ANY lights not installed during manufacture is deemed a ‘modification’ and should be notified to insurers, so I learned. Any mods to lighting adds about 12% to your insurance IF your insurance company allows mods at all. Shop around.

My mistake was using a Green LED wire. It looked lovely but green is only allowed for medical vehicles at the site of an emergency and I’m no doctor . Although, according to the legislation (part II, reg11, section 2, subsections j and m) this only applies to the view from the rear of the vehicle, so green at the front is arguably ‘legal’ but, in reality, are not .

Bottom line, don’t bother, it’s probably illegal or just not worth the hassle adding any form of lighting beyond the vehicles original spec.

Ref:

• Suffolk Police Advice - Car Mods
• Fog light legislation including lateral and vertical distance and alignment.
• General light rules in the UK
• Vehicle inspection manual