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MG TD TF 1500 - Suicide Door Kit Follow Up

Last night I was out on an unlit road to adjust my headlights.
Engine off. Headlights on.
When I finished and got back in I noticed that the red LED warning lights I installed with the door kit, did not go on when I turned the key.
They work fine when the headlights are off. I turn the key and the LED warning lights go on. If I turn on any of the car lights the warning lights go off.
Apparently the car lights have a priority over the LED warning lights and steal all the smoke.
I tried all the terminals on the ignition switch and all the ones that get hot when the key is turned, drop to zero when I put on the lights.

Is there a more reliably place to draw the smoke for the LEDs?

Mort 50TD (1851) Mobius

Mort, hate to say this but not only is your frame twisted, your wiring is too. If what you're saying is true, your ignition would go off when you turn the lights on. And, I'm sure that's not happening. Where are you testing for power? Are you testing relative to ground or to your 12v line? Where did you connect your LEDs? Bud
Bud Krueger

This could happen when the LEDs draw their ground from the switched side of the headlights. When they are off, current will flow from the led through the headlight but so little that they dont show. When you switch them on, the led ground side goes to the same potential as their other side. That's how i switch my daylight driving leds. Description is for neg ground, but similar concept for pos.

Rgds Mike
Mike Fritsch

Bud,
It's my mind that is twisted!
I will try to trouble shoot it on Sun. or Mon.
Mort
Mort 50TD (1851) Mobius

Mort, not being a wiseguy, but what's the purpose of the LED? Does it illuminate to confirm that the door is latched when the ignition is on? Does it illuminate to warn you that a door is not latched when the ignition is on? Does it ever illuminate when the ignition is off? How many wires (what color) come out of the the unit? Bud (the Inquisitor)
Bud Krueger

Mort, I just found the Carolina Custom page, where they say:
A micro-switch is built in for wiring a dash warning light or beeper to alert you that a door has not been latched.
That would seem to indicate that it's up to you to figure out how to wire in the LED. Mike's suspicion may well be right. You may have wired one end of your LED to your 12v line and the other (through the switch) to your light terminal. From their literature it sounds as if the micro-switch is a free-floating 2-wire device. You need to know if the switch is normally open (NO) or normally closed (NC). Can you check that? Bud
Bud Krueger

Bud,
Believe me , I welcome your inquisition/dialog.
Your discussions have helped me, and I am sure many others, many times. So keep it coming.
The first image here is from their instructions. I added the colors and the fuse symbol. My car is positive ground. The micro switch is wired for the normally closed position. Turning the key ignites the light. Locking the door releases the micro switch and the light goes out.
Ignore the beeper.


Mort 50TD (1851) Mobius

Bud,
The next image is awkward to see but I shot it from under the dash.
The blue lead in the bottom center is the lead I used. It is only hot when the key was turned.
Everything was fine till I used the car at night. Now normally you get in the car and turn the key and start the engine then turn on the lights. In this scenario everything is ok. I turn the key and the door warning LED's go on. This reminds me to lock the doors. Then I start the car and then turn on the headlights. So far so good.
It is not to often that you run into the case where the headlights are on and then you turn the key to start. I can not think of a practical case where this occurs. I just happen to stop on the road and turned the car off while I was adjusting the headlight beams. With the headlights still on I then got in and turned the key and noticed that the LED's did not go on.
Mort


Mort 50TD (1851) Mobius

My brain is still to full of sleep but the first consideration would be the LED's. Most likely are negative ground only. I'd verify that first and then reconsider your wiring.
LaVerne

LaVerne,
I am hard pressed to find an explanation since it seemed so simple. I am not familiar with LEDs so I am hoping you are correct. But why do they work with the lights off. Still a positive ground???? If anyone can confirm I would appreciate it. They are so bright I would miss them but I could easily switch to incandescent. Would save me a lot of troubleshooting time.
TIA,
Mort
Mort 50TD (1851) Mobius

Mort, your LEDs functioned just the way you would expect them to if you connected them between your 12v source and the light switch. Mike hit on the head.
Now that I know what sort of switch you have I think I can propose a better way to wire up your system. I'll get back to you tomorrow. Bud
Bud Krueger

Mort, you did not tell us where you connected the other end, so I am illustrating here my theory, drawing what I think is the case for pos. ground. If this is what it looks like, you can test by disconnecting the end that I assume goes to the swathed side of the light switch and holding it to the chassis, then the LED should light up correctly, independent of the lights.

Hope that helps
Mike


Mike Fritsch

Mort, you did not tell us where you connected the other end, so I am illustrating here my theory, drawing what I think is the case for pos. ground. If this is what it looks like, you can test by disconnecting the end that goes to the light switch and holding it to the chassis, then the LED should light up correctly, independent of the lights.

Hope that helps
Mike


Mike Fritsch

Mike, Bud, LaVerne,
Thank you for the info and helping me shake the cob webs from between my ears.
If I was a little bit more electrically conversant I could properly explain what I did wrong. Anyway, here is the improper explanation.
My ground lead went to the wrong place.
My hot lead went to the wrong place.
Other than that everything was fine.

The blue wire where I was picking up my hot wire was the wrong terminal off the ignition switch. What I thought was ground went to the center terminal of the ignition switch.

Per Mike's suggestion I ran my ground directly to the chassis. I picked up my hot lead from the center of the ignition switch.

Now everything works correctly with the headlights on or off.

And thank you all you are a great group of instructors.
Mort
Mort 50TD (1851) Mobius

Congrats, Mort. Sounds as if you're good to go. Just a couple of comments. I'd suggest staying away from the back of the ignition/light switch. Too much of an opportunity to let the smoke out of the wires. If wired properly, any white wire will provide you with the key switched 12 volts.
Red warning/trouble LEDs are good, but you get the same indication if they're not working at all. You might want to consider switching to the use of green LEDs to say that the doors are locked. All you'd have to swap green LEDs for the red ones and switch your wire from the normally closed contact to the normally open contact.
That way, a green LED would tell you that the latch is actuated. JMHO. Bud
Bud Krueger

Bud,
That's a good idea but the thought of struggling those front panels out again makes me cringe. Remember on my car they are not molded around the pipe but forced in behind the pipe. Thank you very much PO.
If you are saying that when in failure mode the lights will stay on, then at least it will draw my attention to the locks.
By the way I don't know if you can tell from the photo of the back of the switch but I have all the wires from the ignition switch feeding various bus bars so I can attach other devices without stressing the ignition switch. I did that when I added the auxiliary fuse block. Comes in handy
Thanks again.
Mort
Mort 50TD (1851) Mobius

Mort, glad it helped. For the on if locked mode, if you have access to the LED itself, you can re-wire it without accessing the switch (using a relay). If it is of interest, I can do another drawing. If the LED is in the door a well, then I would leave it as is.

Mike
Mike Fritsch

This thread was discussed between 23/03/2012 and 26/03/2012

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