LED taillites

[Brian]

I wrote a coupla years back about how my 35, equipped with LED taillites [the multi-cluster type ones mounted on a panel that fits within the confines of the taillite housing], even when turned off, flicker in time with the idling engine- rump, rump, rump; blink, blink, blink. I put that down to them picking up EMF off of the HT leads. I 'think' it was Murre, suggested I fit a resistor? [Where is Murre?- haven't seen him post for a while]....
Anyway, I digress. It has now been drawn to my attention that the taillites are on at all times; very faintly, probably one candlepower? This was first brought to my attention last week, on a terrible wet night....I figured there must be some parasitic draw, with everything being so wet, I thought possibly stoplite switch or similar was wet enough for a bit of stray current to leak through, sufficient to ever so dimly power the LED's.
Today, [a fine day], I have investigated to no avail; disconnecting the brake lite switch had no effect, so I dismantled the light switch, cleaned it thoroughly with contact cleaner, blew dry. No difference.
The draw doesn't register on the [dash] ammeter. Doesn't blow the fuse.
There seems to be a slight leak somewhere....
Where to from here?
Car is 35 sedan, converted to 12 volt, neg earth, running all original type wiring, three brush gene, etc. Stock as , apart from the voltage change.

[koates]

Brian, interesting problem and you have done some good faultfinding so far. Just try removing the single lighting fuse under the dash. I am presuming here that your wiring is the original Ford set up and not altered in any way. I will state that I dont like those rear light LEDs because they are very directional. If you stand straight in line with them they appear bright but if you step out of direct line with them they then appear dull. Also not a great increase in brightness from tail light to stop light. I had them on my 34 and ended up removing them. Also try a substitute earth wire on each light and see what happens. You could also try a diode in line with the feed to each tail light and a diode on the stoplights feed also. I have fitted LEDs to the interior lights on several modern cars and found them to just glow slightly when the doors were closed so I removed them because I couldnt be bothered messing around with customers cars. Have fun, Regards, Kevin.

[Brian]

Kevin, Thank you for your reply. Actually, I dunno what style LED's you tried in the 34, but the ones I run are the same size as the tail light lens, and fit directly behind the lens. They are bright directly behind and at an angle. Far better than a regular tail light bulb, even when fitted into a white painted housing....
Anyway, it's getting dark here, so I went out into the shed and am happy to say there is absolutely no glow emanating from the tail lights. Hopefully, now the light switch has dried out, the problem has gone! Fingers crossed. Thanks again, Brian

[koates]

Brian, good news. I think all that damp foggy weather you have over there gets into the electrics. I have fitted LED bulbs into the dash lights and the front park lights on my 34 and they work well and dont use much power. Its still a 6 volt system. Regards, Kevin.

[satfix]

I would check your grounds. If you don't have a good ground, you can have a slight voltage differential. Most LEDs only need .6v to light (less than 1 v) If your ground isn't good, you may get enough of bleed to faintly light your LEDs. I've seen this several times. I'd recommend you go to each individual tail light and use a alligator clip lead and connect the light chassis to your truck ground. Also, I assume you've properly grounded the chassis to your ground on your battery as well.

Start there, I think you may find the culprit

[farmertom]

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hey brian, this wont help your parasitic voltage draw, but i helped illuminate the taillight buckets on my 37 a little more by lining them with that mirror like reflective very stickey back tape. cant remember where i got it. prolly autozone or other. stuff works. ive had that 3" roll for a few years. good luck, farmertom.

[MGG]

I had a similar problem on my 34 BB several years ago. When I activated the battery switch I could see a slight jump on the ammeter and the tail lights went on very dim. The problem turned out to be in the connections between harnesses in the front left, by the steering box. The bullet connector at the main harness to horn wire was not pushed in quite far enough, nor was the one from the main harness to the light wire harness. I had the wires bundled close together there. The horn wire is always hot and the juice was jumping from it to the light wire at the two bullet connectors which I had laying side by side.
The easy fix was to secure both connections and insulate them with electrical tape. I always have done my wire connections in this way from then on. In troubleshooting the issue, when it was dark in the shop I could see a dim glow where the current was jumping between connectors.