And today's fault is ....

[Guest]

Yes folks, this car's taking the mickey a bit. Now that I have got the car performing correctly again, I went to boys night out at the café and the car ran perfectly. Went to move it next day to get the mower out - no problem, except I noticed that the headlights were on and the switch was on "Off". The side lights were not on and the dip worked. The headlights were coming on with the ignition. The lights were not on when I came home the night before, so why are they on now I wondered. There must be gremlins in there during the night.

So, had a look at the wiring diagram and was surprised to fine that the headlights are not fused, but the side lights are. Anyway, I decided that it had to be the switch, as there really is nothing else, so I took it off and put the multimeter on it and it worked as it is supposed to. I connected the blue wire back on (feed to headlights), switched on ignition and no headlights - unless i switched them on. Problem solved, but I've no idea how or why.

Has anyone else had this fault?

I am now waiting for the next one!

[V Mad]

You must Don, you must have a 'funny' wiring diagram. The headlamps are all fused. Main @25A, dipped @10A.

[Princejohny]

The switch action on one of mine has a loose rubbery feel to it, as you twist it and it's almost as if it clicks onto the next position if you're not careful. How positive is the switch action, Don?
Johny

[KOY 23]

You must Don, you must have a 'funny' wiring diagram. The headlamps are all fused. Main @25A, dipped @10A.

Funny fusing.......Why is a 55watt bulb fused at 10 amp when its a dip but 25 amp when its a main beam??

[Kevin Garrod]

Random guess, but is it because we flash our mains and the higher fuse is needed to cope with the current surge?

[V Mad]

Funny fusing.......Why is a 55watt bulb fused at 10 amp when its a dip but 25 amp when its a main beam??

Because its a Lucas system of course.

[Guest]

V Mad,
I was looking at ROM page 86.00.05. This shows no fuse to the master light switch. Looked again and ah, I see now, the individual fuses are downstream of the master light switch. I was expecting a whacking great fuse on the feed cable to the switch.

Come to think of it, the feed to the light switch is nothing to do with the ignition switch, so I am now puzzled again as to why the ignition switch was operating the headlights?? Maybe something funny going on inside the main/dip/flash switch and somehow I nudged it in the right place whilst fiddling around with the master light switch. I'll have a think.

Johny,

The switch has a nice positive feel to it.

[jleyton]

Hi Don,

I haven't looked to see if this is the case here, but the ROM, including the official wiring diagrams, are often wrong

Cheers

Julian

[brian0443]

Don, if headlights were on but the switch was at OFF then the flasher was stuck ON. I don't have a diagram to hand but power for the flasher comes from the ignition circuit, rather than the normal lighting circuit.
Brian

[Guest]

Brian,

You could be right. But according to the diagram I'm looking at, the ignition switch is not feeding the flasher. However, as Julian says, the diagrams are often wrong, as I have found out in the past. The next time it happens (as no doubt it will) I'll get stuck in and have a look.

[Bob Heritage]

Oh no, daughter of Christine returns

[brian0443]

Don
Just got the wiring diagrams out. If a Mk1 look at no 29..Main/dip/flash switch. If Mk2 its No 22. You will see the Master Light Switches just above them, and that services the lights in normal operation. But look carefully and trace the P (Purple) wire back and you will find it goes all the way to fuse 1/2. Its actually the one labelled Battery Control and is always live.... and bang goes my suggestion as to your problem, as the flash facility is not ignition controlled.
Still, just to highlight that there are two possible ways power can be transmitted to the headlights.
Brian

[Guest]

Went to start it up this afternoon and you've guessed it - the headlights came on with the ignition again. I took the blue wire (that feeds the headlights) off the master switch to see if it was live. It wasn't - but then the headlights didn't come on with the ignition either! More head scratching, but I can only look for the fault whilst it's there. I went for a bash around the countryside in 31°C heat , stopped and started it a few times (a really good hot starter now), but the fault would not re-appear.

So, instead I started playing with the downshift cable at the carbs and found that the outer cable had come out of the recess in the long adjusting nut, putting (or is it puting?) the cable in tension all the time.Then I put the adjuster back to where it was before carb removal and I now have smooth 2nd to 3rd changes again at around 25mph. So that's one each today.

I have not yet got as far as doing a John Cleese on it, but I have been close.

Mussels and chips at the café tonight and if the headlights come on again with the ignition, I will just pretend that I am in a Volvo.

[Guest]

Headlight update.

Last night, going down and back from the village, no headlights with ignition. Noticed that they were on when I stopped to talk to my neighbour. When I re-started, no lights.

This morning I swotted up on all the things that the ignition switch does, with the intention of isolating them one by one when the fault re-appeared. This it did when I switched on the ignition this morning. With the ignition off, I took out fuse 2/3 - ignition control - and no headlights. Put the fuse back and still no headlights, so now I am really confused, as I expected the lights to come back on when I operated the ignition swicth. I now await the next time. What worries me a bit is if I am getting a rogue feed to the lights from a wire that can't take that load and burning starts. So I think I will run with only one headlight fuse in, thereby minimising that risk.

Maybe I ought to just remove the ignition switch and have a shufti at it to see if something odd is going on in there. That's the only device that I operated before and after I removed and replaced the fuse.