Twin Cam Special headlights

[jbcollier]

Yup, check the connections at the ammeter.

[rjbaren]

Yes, I had the ignition switch out and the Brown Blue wire was the only wire that was warm.  I did not check if the panel lamps were on, I turned the rheostat all the way to the left which I believe is off.  I will check the connections at the back of the Ammeter tomorrow.   

[GavinT]

The wiring loom on my S2 was largely unmolested and in pretty reasonable shape.
During my first restoration, I replaced the PO's cheap/off brand ammeter with a new Smiths unit.
The new Smiths gauge had a plastic bowl/housing instead of a metal one.

Years later, I discovered the plastic bowl had melted and partially collapsed around it's innards.
I'd never had an electrical 'event' to which I could attribute this.
Consequently, I'm a little scared of ammeters.

[GavinT]

Is there a post on how and where to install the relay for the headlights?  Maybe the headlight switch is ready for a meltdown.

My relays are located up front on the right hand bonnet drip channel.
They are sufficiently out of the way, out of the weather and suitably close to the loom so as to be able to break out the high and low beam wires to trigger the relays.

[rjbaren]

I have removed the ammeter this evening and found the connections were a little dirty but nothing major.  I removed each wire in turn and cleaned the contacts with Deoxit and replaced the gauge.  I haven't tried the lights yet but I don't think this is my problem.  It was too clean.  I do have an appointment to run the car back to the shop for the lights, maybe I need to leave this one to the pros.

[rjbaren]

I took my car in to the shop and they checked everything over.  Connections at the lights, switches and a large connector behind the dash and cleaned the contacts, put a meter on and after having the lights on for over an hour they said no burning, no smell.  When the took the wires apart they saw no evidence of burning to the wires or the switches/connectors.
So, I brought her home.

[BDA]

I hope that's the end of that story! Good luck!

[rjbaren]

Thank you.  Me too!

[rjbaren]

Well, the story continues and I have questions.  I was installing a stereo and I noticed one of the light green wires from the voltage stabilizer was melted to the back of the panel light switch.  It's an old switch and I believe this is the burning smell I was smelling when turning on the headlights.  Since the car has been at the shop I noticed the lights on the gages are not working.  I talked with Ray at rdenterprises and the panel switch is not available, so I thought I would bypass the switch and connect the single red wire to the two red white wires going the gauge lights, and they would come on with the headlights, but no longer be dimmable.  Since then all that happens is I blow fuses.  The headlights stay on the but panel lights don't light and the fuse blows.   Even if I unplug the two red white wires the fuse still blows.  I am stumped.  Any help?

[jbcollier]

Steady shorts are easy to find compared to intermittent ones.

Get a headlight bulb and hook up two wires with alligator clips on the ground terminal and one of the bulb powers.  Hook this across the fuse terminals.  Disconnect wires at the fuse until the headlight bulb stops glowing really bright.  See what's not working and trace that circuit to the problem.

[BDA]

First, are you using British fuses? British and US (Buss) are not the same. See here: https://www.mgtoronto.com/pdf/Tech/fuses.pdf

You're going to have to trace the gauge light wires (including the light for heater and choke), and all your side marker lights looking for shorts. Since your fuse blows after you disconnect your panel lights (assuming you're using the proper fuses), it seems likely that your problem is with your side markers (see: http://www.lotus-europa.com/manuals/misc/electrical/tcsearly.gif).

It won't help this situation, but after you get this figured out, I'd recommend that you convert incandescent gauge lights to LEDs.

[TurboFource]

I didn't know there was a difference...thanks for the link BDA!

[rjbaren]

So where do I get the British fuses.  I mostly use rdenterprises.

There fuse that was originally in the fuse box read "17amps continuous LUCAS 35A".  I have blown another six 2 & 3 amp fuses in testing.  I have four more 25 amp fuses but I feel that is too high to use.  I plan on getting bunch of 5, 10 and 15 amp fuses for testing. 

Last night my last test I proved myself wrong.  I put in a 3 amp fuse and turned on the headlights and the fuse did not blow.  The side maker lights were on too.  I used my test light and both sides of the fuse were live, which I expected.  Then I put my test light to the lose red wire that feeds the panel light switch, and it also lit my test light.  Next, I plugged one of the red/white wires to the live red wire and the fuse blew.  Side marker lights went out, which I expected.  I ran out of low amp fuses so I stopped.
Today after I get some more low amp fuses, I am going to do the same test with only the other red white wire and see what happens.

I have been looking at the same wiring diagram and I believe one of the red/white wires feeds the instrument lamps and the facia which may be a lose light behind the dash.  The other red/white wire feeds the tunnel lamp.  I am not sure where that light is, maybe by the choke and heater control cables?

This is my first path before I do the headlight test.  Maybe I can isolate between the two red/white wires and hopefully the side markers are the culprits.
     

[rjbaren]

I found two more spare Lucas fuses in the fuse box cover.  so now I connected the other red/white wire to the red wire that supplied the panel light dimmer.  The panels lights came on.  The side marker lights came on.  The tail lights and the front turn signal lamps were on too.  There is a lose bulb behind the dash I assume is the facia and it came on.  I am not sure where it is supposed to plug in, but it lit as well.

Next I pulled the headlight switch and the headlights came on.  The I tried the high beams and they came on too and the inside blue light on the dash came on.  I depressed the brake pedal and the brakes lights work as well. 

Next I tried the turn signals and they do not work.  They used to work. 

I'm getting cloer.

[jbcollier]

If you use a headlight bulb instead of the fuse the brightness of the bulb tells when there's a short while you wiggle and poke about.  Makes finding shorts quick and easy.