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MG TD TF 1500 - New flasher warning light not blinking

Hello,
I'm installing a turn signal flasher warning light because I never remember to turn the flashers off. I'm using a Moss harness with the light green wire #66 from "J" on the flasher can to the bulb. Using a volt meter I see voltage at the bulb, albeit very low. The light is not from Moss, I just picked one up at Napa for $8 bucks. I tested it directly connected to the battery and it lights up just fine so I know the bulb is ok. But it does not flash when hooked up to #66. I grounded it properly I believe to the firewall to a well grounded bolt.

Any suggestions why it won't flash would be appreciated!
Ed
efh Haskell

That is exactly what I did and haven't had a problem with the indicator light (although plenty with the flashers in general, mostly ground issues). I grounded the warning lamp to the same bolt as the battery ground connects to.
I guess my suggestions are a) connect it to the battery ground to make sure that is good b) make sure the connections are good on the lamp housing and c) what flasher unit are you using?
With my new $6 Ace Hardware turn signal switch, I also needed a warning light to remember to turn flashers off :)
Geoffrey M Baker

Geoff, I got the $8 Napa 3 way switch and one of their warning lights on the same display rack. Also a little mounting bracket made just for these items. I already did all the other things you mentioned. Flasher can came from Napa a few years ago and works fine, don't remember model #. Lamp tests fine also. Stumped...maybe these Napa lamps require more voltage than the can is pumping down wire #66?
efh Haskell

Bring it by the house tomorrow morning and I'll look at it ...if you want. I'll be out in the shop.
MG LaVerne

I'm wondering though if the L(amp) circuit on the flasher has never worked... you wouldn't ever have known until you installed this lamp! Try another flasher and see what happens....? Modern bulbs don't require any more voltage than the old ones (generally less in fact with technological advances). I'm using wire 66 (light green) and it is not giving a problem; and I'm using a very old Edison bulb in the original dash indicator light and it lights up fine.
But now I'm thinking... you bought a switch and a lamp and a mounting bracket. so you should have a three way switch (L to L bulb, middle to power, R to R bulb) and a indicator lamp wired to the middle leg of the flasher (L) and to ground. If you have it wired like that, the only possibilities are the ground is bad, the flasher L circuit is bad, or the bulb is bad.
One last possibility: is the Napa bulb an LED bulb? If so it may be polarity-specific and if you've got a positive ground system, it won't work unless you wire it in reverse.
Geoffrey M Baker

No, #66 gets wired to the P terminal, not the L. And, like I said, the bulb works fine when connected directly to the car's battery so it's not an LED problem. And I've traced all through the system with a voltmeter. It's getting voltage, but very weak for some reason?
LaVerne'l fix it! I'll call tomorrow morning first LaVerne.
Ed
efh Haskell

If you are using an LED bulb you may not be drawing enough current to make the old fashion flasher can work. There is a small amount of current going though the can when it is activated but before the relay closes to make the traditional edison bulb glow - not enough to see with a regular incandescent bulb but maybe enough to make an LED glow weakly. It's just a thought but you may need to wire a dummy load (resister but I have no idea what size or resistance) in parallel to create enough current draw to make the flasher work properly.

Jud
J K Chapin

I agree with Jud; if its an LED it may not draw enough to make the flasher fire. You can buy resistors at www.superbrightleds.com that will make sure there is enough load for your existing flasher.
Geoffrey M Baker

How can a LED bulb be determined visually? Like I said, there is no mention in the packaging or anywhere else this might be LED? The actual "bulb" part is hidden inside a sealed plastic tube and lens and does not come apart without some force (I've tried).
Here's a photo. $4 bucks at Napa or True Value vs. $$$ at M.
Ed


efh Haskell

Just a WAG but I wonder if LEDs work like old fashioned diodes (when I took EE diodes were big glass bulbs with an annode and a cathode) such that using an ohmmeter it would read high resistance (virtually an open circuit) in one direction and little to no resistance in the other direction.

Jud
J K Chapin

efh, if it's a polarity specific LED you can test by putting it back on the battery. It will light up one way but not the other.
However, it may not be polarity specific :)
Geoffrey M Baker

It lights up either way from the battery. Just did a "chat" with Napa. They "don't have that information available".
efh Haskell

Bad flasher can! "P" terminal had obviously never been tested before. New can and 5 minutes later it flashes! Brightly too! $4 Napa warning light vs. $32 other sources. Just plastic but good enough for a driver imo.

Thanks again LaVerne Downey!
Case closed.
Ed
efh Haskell

This thread was discussed between 13/05/2014 and 14/05/2014

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