7 replies to this topic

[AzMaN]

So ive had a look over my new purchase, bringing me back into the mini scene after a few years out with a 1976 clubman (998)

dosnt look in too bad condition, front floors need doing, subframes arnt in the best of conditions, exhaust leaks like a sive, still on drum brakes .

Compresions ranged between 102-110psi which i didnt think was too bad.

Pulls away nice but seams to lack power at certain revs, has the speed there just takes a long time to get there, but a RR sesion should sort that.

my question is this, on the electrics (which are shockingly poor to look at) i have a strange fault, when i put my sidelights on both front and rear lights come on as they should, when i put the dip beam on, i lose my tail lights, currently the numberplate light isnt wired in but i cant see that affecting it in only one position.

am i looking at a switch fault? i havent got any decent drawings any more, my haynes manual has more oil on it than whats probably in the car.

[dklawson]

am i looking at a switch fault? i havent got any decent drawings any more, my haynes manual has more oil on it than whats probably in the car.

You will need to get a manual (wiring diagram) that you can read and really sort through this.

I doubt you have a switch problem. You probably have a parasitic earth problem. Because of how Lucas wiring is arranged, failure of the earth in one circuit can cause one circuit to feed through another to find earth. That can cause lights (and other things) to turn on and off when you are not expecting it. With the wiring diagram you are likely to find the manner in which the circuits are connected and then you can hopefully figure out which earth connection is at fault and correct it.

[AzMaN]

thanks, theres a few little wiring issues on this car so i think i shall get a new manual, maybe a pdf version so i can just print the pages and get them oil'y then reprint them.

time and a multi-meter is required i think.

[tiger99]

The headlights do not share an earth with the tail lights. It seems to me that the light switch is defective.

You can, and should, make an improvement to the earthing by taking each light cluster to its own earth. Running the headlight earths back to the bullet connectors behind the front panel (on a roundnose, not sure if they do that on a Clubman) is very bad practice, as a single earth failure takes out both headlights, possibly when you are on the move in darkness. I really don't know what BL were thinking about to wire it that way.

Do the same at the rear too, the black wire from each light cluster to its own earth bolt. It makes things more reliable and saves a few feet of wire.

[Dan]

Are you sure the sidelights don't also fail when the headlamps are on? What about the panel lights?

[dklawson]

The headlights do not share an earth with the tail lights. It seems to me that the light switch is defective.

That is not what I said. I said he may have a parasitic earth connection where one circuit finds earth through another. That's totally different than sharing an earth.

[tiger99]

Sorry, I now see what you mean. Different terminology on each side of the pond. Actually I thought you would have called that a sneak circuit. But I still can't see why the tail lights would go out when the headlights were on, unless they were earthing via the headlights, which given the wiring layout seems to be impossible. Unless, of course, they are earthing via the indicators, which they will do if the rear earth is missing, so the current passes through tail light, which will be moderately bright, rear indicator, fairly dim, front indicator, also fairly dim, and somehow to earth, which must be via the headlights.

Seems to suggest that the rear earth has failed, and the front bullet connectors are messed up, so that headlight earth is tied to indicator earth but not body, and non-working headlight filament is tied to actual body earth.

I always recommend fitting a direct earth connection for each light cluster for safety, and to make things like this simpler to diagnose. Uses less wire too.

He has not told us yet what happens when he tries the indicators, but I expect it will be strange, to say the least!

Anyway, sorting out the rear earth connection (daft, inaccessible place under the fuel tank) and front bullet connectors should get it working for now.

[AzMaN]

i havent had a chance to check any other combinations of lights yet, work and rain put a stop to any tinker time, hopefully tomoro will give me chance to have a play.

thanks for all your sugestions .