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Alternator Or Fuse?


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#1 notsominiphillip

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Posted 02 March 2010 - 07:32 PM

i have an austin mini mayfair
1984
i picked it up yesterday and drove it home, half way home it juddered and stopped. managed to bump start it and got it about a mile then it juddered and stopped again. got some jump leads and jumped it it drove home no problems but would not start when home. by the time i got home i was in darkness no inside lights and no head lights...

my brother has taken a look at it and thought it might be alternator however he changed over 2 bulbs in the dash the red and orange ones which allowed the car to charge but now my lights wont come on unless its on high beam...

i have checked the battery with the multi meter which now suggests the battery is charging as it is within the recomended guide lines. all fuses in mains box are fine and both bulbs that were changed are not blown....

i have a haynes manual and have racked my brains any help would be much appreciated as i want to get her on the road asap!!

thanks in advance ^_^

#2 dklawson

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Posted 03 March 2010 - 12:38 AM

I have no explanation for why your headlights only work on high-beam.

You said that the alternator works as you've measured it. What and how did you measure?

The voltage across the battery with the engine off should be around 12.5V. After starting the engine, you should measure between 14-14.5V across the battery terminals.

You said that you changed the dash bulbs around and this somehow got things working. For future reference, the charge warning light is the red one. The orange light is typically the oil pressure warning lamp. What exactly did you switch and how?

The red charge warning lamp is more than just an indicator, it is an important part of the charging circuit. Power flows from the ignition switch, through the warning lamp, then off to the field coils of the alternator. Current MUST flow through the warning lamp to the field coils of the alternator in order for the alternator to work properly. In short, the warning lamp is more than just an indicator, it's an important, conductive part of the charging circuit so you shouldn't bypass it and/or swap it around unless you are very careful with what you are doing.

The charge warning lamp should behave as follows:
1) Engine off, key out - Red charge warning lamp "OFF"
2) Engine off, key in the run position - Red charge warning lamp "ON"
3) Engine running, key in the run position - Red charge warning lamp "OFF"
Anything else indicates a charge system fault.

#3 notsominiphillip

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Posted 05 March 2010 - 06:33 PM

Hi its the brother.

Changed for a new alternator now and its charging fine now, all lights (but the rear lights) working again brake lights fine just when you try to put the normal lights on they aren't working. any ideas on that one?

Cheers.

#4 dklawson

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Posted 05 March 2010 - 11:37 PM

Hi its the brother.
just when you try to put the normal lights on they aren't working. any ideas on that one?


Do you mean when you turn the headlight switch "on" the headlights do not come on?

Mini wiring may differ a bit from year to year but on my early car the headlights are not fused and run directly off a permanent live feed. While it could be a fault of the switch or the "hot" wire supplying it, I would focus on checking the electrical connections behind the slam panel at the front of the car. Each headlight will have its own short bit of loom that joins near the middle of the car. The multi-connector female electrical unions can fail. Since it sounds like neither headlight is working, pay particular attention to the earth wire connection for the headlights.

If you don't have a multimeter, this will be a good excuse to buy one. Even inexpensive ones can be very handy for checking voltage (both in a car and in the home).

#5 notsominiphillip

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Posted 09 March 2010 - 09:56 PM

thanks very much for your help have done as much as we can do now and its off to a mechanic for the last few bits :thumbsup: she is on the road now!

#6 dklawson

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Posted 10 March 2010 - 01:23 AM

Were you able to resolve the wiring/lights issues?

I'm glad you're on the road. Do let us know what you and/or the mechanic finds.

#7 notsominiphillip

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Posted 12 March 2010 - 09:46 PM

yes we changed the head lamps to standards as they were angle lights it seems to have fixed all the lighting problems it may have been a fault with the lights?? ask no questions and hope for the best!!! im going to get her checked over anyway incase i have missed something but its looking good just in time for the mini season ;) thanks again




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