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MG MGB Technical - LED Turn Signal Bul for a 74B

I've searched but I can't find a recent answer,

Where can I find an amber 1157 front running light/turn signal for my 74 B that doesn't require a ballast? Does that exist?
Dan Hiltz

1157 is a filament bulb that doesn't need a ballast. If you are replacing that with an LED then you will need to add a dummy load in parallel to make the original flasher unit work correctly.

It's not the bulb that needs it, they will light up on 12v but draw a current which is a fraction of a filament bulb, hence needing the dummy load to replicate that current which is what the flasher unit senses.

Some LED suppliers do talk about an internal resistor but you have to know whether it is a series resistor to reduce the voltage to what the LED elements need, or a parallel resistor to replicate the load. The latter take the same current and produce the same heat as a filament bulb, they may or may not be brighter.

Some after-market flasher units are capable of flashing led bulbs at the correct rate without dummy loads, but they do not have the safety feature of the original which lets you know when one corner is no longer lighting, and there may also be a delay in lighting up when you first operate the switch.

A huge minefield littered with cans of worms.
paulh4

Dan
I tried a few different brands in my VW golf and had no flashing happening and a globeout warning on the dash. Then found these and they work perfectly - and bright
Can't say if they'll work in your MG but replaced normal globes in the golf without any issues-
willy

https://www.ebay.com.au/itm/305378579188?
William Revit

When I put LEDs on the turn signals and brake lights of my MGA, I used the recommended transistorized flasher. It's three pronged and a direct replacement for the resistive flasher. I don't know if it tells you when a bulb is out but LEDs are supposed to last a long time.

Jud
J K Chapin

Dead link.

Anyone selling LED bulbs as replacements for filament is likely to have a 'recommended' flasher unit ...

Not even Lucas understand the 'technology' now, they are selling SFB115 indicator flasher units (MK2 MGBs and later) that have hazard flasher innards which only come on after a delay and will flash anything from 1 to 4 bulbs.
paulh4

"Dead link" Sorry Paul -looks like you might need the whole link. As said previously they work fine in my golf where other led's wouldn't flash

https://www.ebay.com.au/itm/305378579188?_trkparms=amclksrc%3DITM%26aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20240304162621%26meid%3Deeefa084ceff4810a0ce957b5f0a9bff%26pid%3D102020%26rk%3D1%26rkt%3D20%26sd%3D305378579188%26itm%3D305378579188%26pmt%3D1%26noa%3D1%26pg%3D2332490%26brand%3DSignal&_trksid=p2332490.c102020.m5276
William Revit

Willy

You needed to remove the ? from the end

https://www.ebay.com.au/itm/305378579188
Dave O'Neill 2

Cheers Dave
William Revit

'Crambus' technology - sounds like public transport in the rush-hour :o)
paulh4

all i know is paul is that they work fine in my golf and the 'globe out' warning on the dash doesn't light.
William Revit

I have 80s/90s electronic flasher units on both my MGBs for a decent flash rate and wanted LEDs that would hopefully be brighter without having to install dummy load resistors. I bought a pair described as 'canbus error free' but they flash at double the rate of filament with my flasher units, and wouldn't flash at all on the original thermal unit.

Some of these LEDs are described as 'no hyperflash', which refers to when they are used on cars with 80s/90s flasher units as they have the correct load internally and should flash at the correct rate so better to aim for those. It does mean they get as hot as filament bulbs, and I've seen reference to some having cooling fans because heat is the enemy of semi-conductors!
paulh4

This thread was discussed between 20/10/2024 and 30/10/2024

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