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MG MG Y Type - YA electrics

Have fitted a power socket under the glove-box of my YA to use for things like a GPS, trouble light etc. After working out that that the GPS wouldn't work because it needed to have a circuit that was negatively earthed it is up and running OK, on it's own private circuit through a new fuse box.

Next job was to mount a switch on a bracket under the dash so decided to make use of the bolt holding the steering column to the bracket behind the dash. It's now in place BUT something has caused a short circuit maybe?

After accidentally blowing the horn several times during the course of this work as I fumbled around, the horn button now doesn't work - but if I turn the turn indicator switch to the right, the left blinker operates and the horn sounds off. Don't try turning left - that doesn't do anything.

I didn't disconnect the battery while I removed the clamp bolt before reinstalling it with the switch bracket attached. Have I short circuited the wiring at the base of the column when the column moved down a little bit, inside it or what? Anyone with a bright idea? I'm no electrician!

John Turner
Y6214
J B Turner

Hello John,
Don't panic you have not short circuited anything, you have simply disturbed the God of Lucas Electrics, andyou are suffering the first symptoms.

In my nearly 30 years of experience with Lucas electrics 99% of problems relate to a "bad earth connection".

In your case the steering column electrics have been using the bracket as an earth. There should actually be a wire at the rack end of the column to earth the horn and trafficators.

The trafficators are now being used for the horn earth.

I'll take a photo of the earth wire on my column and post it here later - in the meantime, download the wiring diagram from the IMGYTR website and understang how the horn and trafficators are supplied with power and how this power finds it way back to earth.

I would strongly advise you also change your car to negative earth - it is risky to have 2 different polarities in a car - it will lead to dramas one day.

It will take you less that 30 mins to study the changes and carry them out.

I will be in Tassis in mid November in my YT, so happy to meet up & share a coffee and MG chat about Lucas electrics then .
A L SLATTERY

Hi Tony

Be good to meet up when you're down here. Send us an email closer to the time. Like you say it would appear that the system is earthing the wrong way at present. Just talking to my son in law who runs an auto electric business in Tumut, but a bit hard for him to diagnose when not familiar with the set up. Will have to sort it before then as we are heading off on a trip down Tassies east coast soon with ten others.
John
J B Turner

Hi John, Here is a photo of the earth cable for the steering column. You need to install this if it is missing.

cheers

Tony

A L SLATTERY

Hi Tony, The missing earth cable is not missing unfortunately, so there is something else somewhere causing the problem. Also found that a left turn indication will operate the fuel pump. So it has to be an earthing problem I guess, but where.
John
J B Turner

Hi John,
The earth wire may be there but is it working ?.

You need to study the wiring diagram and check there is power at all the places expected - a test light or voltmeter will do this for you.

Do you have an early or late regulator (are the fuses part of the regulator or in a separate box) ?.

You can fix this - we are all here to help & learn from your experience. There is nothing complicated in Lucas electrics.

Tony
A L SLATTERY

Steering column earth wire is working as far as I can determine. I earthed the upper section of the steering column to the chassis with jumper leads without effecting any change in the problem. Bottom terminal of the four is live, with the other three not.
John
J B Turner

Could the problem be that the upper section of the steering column has moved upwards - of the 4 contacts on the column that the wires from the steering wheel attach to, it is the second one that is live, whereas I would have thought it would be an end one.
John Turner
J B Turner

It is more than probable that you have disturbed the alignment of the "fingers" to the slip ring. Easy way to test this is with an ohmmeter from the slip ring terminals to the terminals behind the horn push.

The hard part sometimes is getting the horn push shell out of the steering column which requires infinite patience if it is locked in there with corrosion!

The order of the slip ring, from top left to bottom right as you lean over it are:

1. Left Turn signal
2. Right Turn signal
3. Supply wire
4. Horn
Paul Barrow

I think Paul's comment of 2nd Oct is correct. I had this problem after replacing the dash. The YB manual gives a dimension for setting the slip ring assembly,
(dimension 'N' in fig M-3), page M-3 as 11/16 inch. This seems to be the same for the YA.
In pratical terms its easier just to set the column clamp back in its original position which on my car was very obvious from the state of the chrome plating! Then check if things are working OK.
Hope this helps

Tony K
A B Knowles

Situation back to normal, with blinkers, semaphores and horn working as supposed to. Thanks for the tips and help received.
John T
J B Turner

This thread was discussed between 01/10/2011 and 08/10/2011

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