Electrical not working correctly '56 Mk 1

I now have reconnected the electrical wiring at the dash and light fixtures that the PO had disassembled. I installed 15 and 25 amp fuses (replaces Lucas 35 and 50 fuses). Connected a warning light at the + battery terminal to ground. A few things are not connected and, they get power from the A4 terminal on the fuse block: Brake light, Reverse light, heater fan, wiper motor and wires to wiper switch.

Clock and fuel pump are not connected.

Near the firewall there are 3 wires from the loom with bullet connectors, their destination is still to be determined.

Both rubber bullet connector blocks on the fender walls, 5-way on right and 10 way on left, have been replaced and ground clips renewed, attachment points on fender sanded to bare metal.

My electric system function results:

Horn - weak buzz and warning light on (connected to A4 terminal)

Turn signal: right side - warning light flashes, Turn signal left side – nothing. (connected to A4 terminal)

Sidelight: Dim orange glow, warning light on.

Headlight: Nothing, warning light on.

Foglight: No Foglights connected, warning light on when switch activated.

Panel lights – nothing.

Taillight – nothing.

License plate light – nothing.

This works:
IGN light illuminated with key on.
Interior Light switch provides power to lights.

I have no idea how to troubleshoot the above faults and wondering if the HL switch faults might be located before the HL switch? And, could the horn and turn signal problems be related to the other A4 equipment that is not yet connected? Thanks

Think the first job would be to sort out the 3 disconnected wires !
Dim lights could be a bad earth ,
Horn -weak buzz , could it be the horn itself !

What I tend to do is start with the basic , rig up a test bulb , pull the live wire from the part that is not working , see if there is live getting to it , by seeing if the bulb lights up , 1 wire to the live and the other going to a good earth , if that’s ok , I then check the earth on the part , pretty basic stuff I know ,
If no live just follow the wire back to you get power , same with the earth !

Ian makes a very good point about the three not connected wires. Identify those circuits and connect then one by one work your way through using your diagram.
Much easier to start at the fitting end and work back from there using Ian’s suggestion of the light or a test meter.

Good luck and keep us updated on your progress.

I spent a few weeks trying to figure this out and I am wondering if anyone can decode the following:

I found if I use a jumper wire from the power terminal of the headlight switch to the red wire for the panel lights I get full brightness on the panel lights. Same happens when I jump power to the tail light wire and side light wire – full brightness.

When I reconnect these wires to their respective terminals on the HL switch they don’t put out the same intensity and, the test/warning light installed between the battery and earth connection glows. Does this indicate a bad switch?

The headlight wire, when jumped to the power wire: the test/warning light glowed.

When I removed the headlights from their 3 blade connector socket – there was nothing at the test/warning light.

I opened a section of the loom below the fuse block on the firewall, wires looked OK.

Does any of the above indicate a specific fault?

Thanks

Generally speaking, when a headlight glows dimly, it means there is a bad ground connection, dirty or corroded. Or in your case with the other lights, it may be a bad connection in the headlight switch.

I once took a 3 position headlamp switch (as fitted to my 3.8S) out of the car and took it apart. It was all gummed up with old grease making bad connections. Cleaned everything and put it back together with full success.

That does indicates a bad lighting switch. As @John_Quilter wrote, you can open them and clean them. I usually start by using my ultrasonic cleaner and a double bath, using Turpentine or Alcohol to dissolve the congealed grease and grime, then a squirt of contact cleaner/lube spray. This is often enough to revive a switch, but if the contact metal is worn then sometimes you need to open the switch and bend the wipers to make better contact.

A Continuity Tester (multimeter that beeps) is indispensable tracing where wires go

have wire on hand to test run new links, using a test light to chase good 12V

regarding the headlights, after checking earth, wiring a relay near the headlight will not only help isolate the fault, but also good practice for several reasons (can be temp for fault finding)…saves current thru switch, prolonging its life, saves current going thru cabin wires = less fire hazard, more power to globe means brighter lights

Agree with Mr Quilter and Mr Waugh. Test your switch. You can test either resistance (ohms) from the panel and sidelights to the power terminal, or voltage to the panel and sidelights from the power side.
It is not hard to pull the switch. 1/4 " drive sockets to remove the wires & bracket. Mark everything’s location, or take pix, or both. If you want to take apart the switch, do it carefully on a big clean surface. Remember the switch handle is held on by a detent ball. I rebuilt mine & thought it was ok, but after I reinstalled it it developed the kinds of intermittant problems that lead the restorer to the loony bin. I installed a new one - wouldn’t ya know it - upside down! So far I’m living with the switch handle pointing up rather than down.
Getting an old wiring loom to work is a real challenge. I bought a set of wiring numbers - reels of tape with #s on them - in a little red dispenser on Amazon. Very useful for marking wiring runs. I would also suggest replacing the connector blocks on the front inner fenders. Good luck. David

Thanks for the comments. I removed the Lucas HL switch to replace it with a donor from my parts car. The donor switch does not have the spring clip/push button to hold the knob securely. Is the spring clip/push button removable? It looks like it might be easily removed but, don’t want to mess with it if not removable.

I previously wrote: “When I removed the headlights from their 3 blade connector socket – there was nothing at the test/warning light.”

I tried another test with bulbs connected on the HL circuit: jumper wire from brown/blue power wire to headlight wire, removed HL bullet ends from their blocks on the fender, used a test light probe - one end to ground, the other into the connector that corresponds to the HL wires. Probe test light glowed - both left and right side for main and high beam - the test/warning light connected at the battery did not glow.

I reconnected the wires to the connector blocks and moved them a bit in the area under the fender but the test/warning light continued to glow, did not flicker. Do these results indicate a problem with the wires going, from the connector block to the headlight socket? The socket? The bulb?

Thanks

I recently fault found on a vehicle that made Lucas wiring look like Gods gift.

In the end, the ONLY way I could sort the issues is run a long loose wire to duplicate the wiring/connectors etc.

Use the long wire to go from battery to source, back & forth, leave everything connected.

In the end it turned out to be (mainly) intermittent broken wires within the harness!
(wires would usually pass a continuity test, but when more current flows, they became unreliable)

I am a qualified Electronic technician by trade…another listed commented he is an aircraft maintenance technician, and they “piggyback” wires like this “all the time” to fault find :hushed:

My neighbor (who knows more about auto electric than I do) stopped by while I was opening the loom that contains the headlight wires to/from the dip switch. He checked a few things and determined the ground point on the left fender bracket (bracket holds 10-way rubber block) was bad.

I had previous scraped off the sprayed on insulation at this ground point and sanded the metal until it was bright and shiny (both sides of fender) before the ground clip and bracket were reattached.

Even with the metal prep, the warning light between the battery ground post and firewall would glow when the headlights were on.

We ran a new wire from the fender ground point to the earth terminal of the battery and everything worked as it should and, no warning light illuminated. Headlights, sidelights, taillights, turn signals, panel lights, horns worked. Headlight switch worked when reinstalled.

Did my additional wire mask a problem that still needs to be fixed or, should I plan on making the wire a permanent part of the electric system? Thanks