MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Opps!!! I let the smoke out

Just for the hell of it and because I must tinker(genetic disorder),I decided to add a set of air horns and halogen headlights. Both through relays. Of course Mobius gave me the usual problems and it took twice as long as I expected. It came out fine except it looks really hokey with the red horns. It's the Moss kit.
The PO removed the horn from the right side to make room for the old supercharger. Tooting the one horn just doesn't get you any respect on the road.
The air horn doesn't sound beautiful but it will get you attention. That's what I was hoping to accomplish.
But just when you think things are going well....... see the next post.

Mort


Mort Resnicoff (50 TD-Mobius)

I got the wiring done for the halogens and the relay sockets installed. Turned everything on to test it and that is when the smoke escaped. I turned everything off and reached for the fire extinguisher. I held off using it as I could see the smoke escaping and no fire.
Next I took one look under the dash and did what any backyard mechanic would do. I slammed the garage door and went to sleep.
I had dreams of a new harness, pulling the seats and floor board so I could get under and rewire the mess and replace any number of dashboard instruments. I assumed I wired something wrong.
Well today Mobius was kind to me(I think).
When I looked at it closely today I believe an arc jumped from the hot wire that goes from the ignition switch(H) to the horn/dipper switch to a ground wire. That sent current directly to ground. That ground wire goes to a buss bar I installed to ease my wiring nightmare. You can see the three little blue jumpers that make up the ground side of the buss. Just to the right of them and in the background is the blue insulation completely melted off the stranded wire. The wire is just above the insulation.

I've cleared the rubble and tried everything again and all seems to be working. The stop light wire from the ignition also got toasted so I will replace that also.
Whew.... Could have been worse.
Mort



Mort Resnicoff (50 TD-Mobius)

it's amazing how much smoke a measly little 12 volts holds. Looking at the accessory port (cigar lighter socket), I'm guessing negative ground conversion - maybe? Or just carefully located?
Jud
J K Chapin

Ground wires are black on Neg ground systems, red on pos grd ones.
ALWAYS!
The smoke knows that blue are headlight circuits, so it gets confused and tetchy.

Can you say
FUSE?

What were the voltage readings at the lamps before you screwed with it?

When do kids get old enough to listen to directions?

FRM
FR Millmore

Looks like Smurf fingers.
L E D LaVerne

Fletcher - I have to disagree with you, black is always ground, regardless of the polarity - look at the wiring diagram and color key for the TD/TF/MGA/early MGB. Cheers - Dave








Daved DuBois

An impressive bird's nest that is... At some point you may want to realize your dream of a new harness ;-)

Mike
Mike Fritsch

Jud, Positive ground. The accessory port is "reverse" wired and has been working fine for a year or two.

Fletch, I know it's shameful but color codes don't mean a lot on my car. The PO did a lot of creative wiring behind the dash. I just trace the lines. I used the blue for the ground jumpers because that's the color I had.

Mike, It's hard to believe but the harness does not appear to be very old.

I increased the number of wires in my birds nest considerably when I put in a 16 fuse block and diverted lots of wires to it, through the fuses and then back to the instruments.

I believe there was a direct short from a hot lead behind the ignition switch to ground and the nearest ground circuit got toasted. That local ground kept the current from running through the harness and making a real mess.

More to report as time permits.
Mort
Mort Resnicoff (50 TD-Mobius)

IMHO:
Classic example of why you should carry a fire extinguisher in the car & have a cut-off switch!

Glad it wasn't worse...as in "TD Flambo".
(Flashback to frying Austin in rain storm 1970...something I wish I could remove from menory)

Looking at the picture....
"Dead blue Smurf fingers" (red arrow):
Are those just jumpers from one terminal to the next?

Yellow arrow: "buss bar" to do same thing as jumpers?

Let me know if you need some "buss bars" for your terminal strip.
Pretty sure I have a bunch of them and could mail you a few! (no charge)

The again...looks like they did act somewhat as a "fuseable link" so maybe smaller wire for the next go-round wouldn't be a bad idea!


David Sheward

Dave DB - I knew that! But I was just looking at some Norton stuff, and the Lucas motorbicycles use red for + earth!

Mort - Now you have found out why I was insisting on main feed fuses, at the source. I almost had a heart attack when I saw your subject line, don't do that again!

It is a lot easier to get some correct coloured wire, and improve the situation, than it is to aggravate it and trace wires forever in homage to DPO uno, and be DPO dos as well. You will think about this a lot when smoke starts escaping at 90mph 742 miles from home in the rain!

1961 or so - Brother of a friend was in the Air Force, and brought home a lot of then hi-tech wire from fighter planes. All white. He wired his 37 Ford with it, using the spider technique - anchor one end at the terminal, then stretch the wire in a straight line to the other terminal. No harnesses, no bends, no support brackets, no slack. Then they asked me to come help them make things work - Behind the dash - Awesome!

FRM
FR Millmore

Fletcher,
"Lucas motorbicycles use red for + earth"

I forgot all about that...but you are correct!

So...must be an old Norton guy working in a factory hooking up the "pig tail" that was on my Atlas"t" 2 post lift! LOL

No documentation for wiring so when the Amish guys helped me install it I hooked up "temp" to the pig tail hanging off the electrical conection box.

220 circuit 1 Red, 1 Yellow, 1 Green wire.
Easy right? R/Y 220+ legs, G ground.
WRONG: RED was ground. Lit up an Amishman leaning against the post when I threw the breaker.

His comment: "Thats why we use Pneumatic tools, eah...they don't bite ya".
David Sheward

Wiring harness for the color blind Fletch. Your buddy ever own a TF?


L E D LaVerne

Had to grab the camera in an instant to take a picture. Lots of smoke, fortunately no damage...

Lesson learned: always disconnect the battery when working under the dash...

Jasper


Jasper Nederhoed TD #3966

Jasper,
That is a classic picture!
I am going to print that one for under my Lucas sign and jar of replacement smoke the garage!
Have a special place for it...right next to this:


David Sheward

;-)
Jasper Nederhoed TD #3966

Mort,
Need smoke?


David Sheward

LED - Not his work, he didn't route wires like that, and certainly had no tie wraps! The engine in that 37 looked as if it had been caught in a spiderweb, since he did the same thing under the hood.

Jasper - Must be a positive earth car - the smoke is draining up! Great picture.

FRM
FR Millmore

Jasper,
It's interesting to note that European electric smoke is the same color and texture as ours.
Mort
Mort Resnicoff (50 TD-Mobius)

But in "OZ Cars" ...would the smoke go "down under"?
David Sheward

David Sheward,

"Let me know if you need some "buss bars" for your terminal strip.
Pretty sure I have a bunch of them and could mail you a few! (no charge)"

Dave if you've got three or four of those little buss bars you can spare I would appreciate it very much. Would be a lot neater.

Thanks,
Mort

Mort Resnicoff
2 Whitehall Road
Monroe Twp., NJ 08831
Mort Resnicoff (50 TD-Mobius)

Before I got into the air horn project my horn would work intermittently. To resolve this I added a ground wire to one of the screws. Then I made the mistake. I thought the end of the terminal strip was ground and hooked it up there. But that was directly connected to T on the ignition switch. Everything was fine until I started working on the halogen headlights. When I got them hooked up I tried to test them and turned the light switch to the stop light position. That put 12 volts directly through the new ground wire I put on the horn. Out came the smoke. The wires from T to the terminal strip and from the terminal strip to the horn are shown below in a slightly damaged state.

As Fletcher said if I had properly color coded everything I would not have made that mistake.

All is repaired and all systems are go.

Mort


Mort Resnicoff (50 TD-Mobius)

I guess those of us not clever enough to convert to negative ground just need to stop thinking + & - and start thinking Hot and Ground.

jud
J K Chapin

The European smoke may look the same, but it comes out in liters, not gallons (at least on the continent); probably pints in the UK...

Jasper, nerves of steel to take that pic. Did you have the power off already when you took it or were you waiting for the flames to come ?

Mike
Mike Fritsch

I fixed the wiring on an MGA once where the previous owner, an engineer, built his own wiring harness. There was an issue with the turn signal relay box and the voltage regulator.

It was absolutely perfect, cloth wrapped, wires layed out and emerging exactly as the factory did, beautifully soldered connectors... All done with the same spool of red wire. Every wire.

But hey, it was a red MGA...
Dave Braun

Mort,
Finally got home ...buss bars on the way to you.
Cheers,
David
David Sheward

Thank you David.
M Resnicoff

This thread was discussed between 28/02/2013 and 05/03/2013

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.