9 replies to this topic

[The-Womble]

I pulled my Mini out of the carpark this morning, charge light came on at ignition and went off once it'd fired up as usual, but within a minute of setting off I noticed a bit of smoke drifiting around the dashboard area. I immediately pulled over and switched everything off. The smoke diffused and after struggling to see where it had come from or if anything was unusually hot, I fired it back up to see if it'd do it again. It didn't, but the charge warning light stayed on. Everything is still working on/in the car, it seems.

 

My car is an '89 Mayfair although someone has retrofitted the centre clock setup, but unfortunately they have used some of those horrible choc-bloc connectors. I found that the brown wire with yellow stripe (to charge warning light), and a black (surely an earth?) wire had melted the plastic slightly. Thought it might be the alternator over-charging, so I've changed the alternator but the light still remains on the dashboard. It is still only registering ~12.5v across the battery too.

 

I can't get my head around what could be the issue (other than that knackered plastic sheathing) or what might have caused it? Surely if the light illuminates, the warning circuit is not the problem? Is that correct?!

 

Thanks in advance!

Chris

[KernowCooper]

You need to look carefully at the charge light wiring as it goes from a ignition controlled feed in a special bulb holder which is not earthed, 12v feed goes into the bulb and the wire out the bulb goes to the ind small terminal on the alternator. See here how it works http://www.theminifo...g-how-it-works/

 

Once you have read that and understood the system then do the alternator tests here http://www.theminifo...ng-basic-tests/

 

 

There is enough information to follow there to identify where the problem lies, once you've done those shout back

[The-Womble]

Thanks for the info Kernow, I've had a quick read over it. I think I understand how the warning light system works now! Just to clarify my previous post, the light is connected correctly; the black wire is not connected to the light, but does seem to have melted a little. Whether that is just because it was touching the brown/yellow wire which was very hot, I'm not quite sure.

 

I have checked the fan belt for tightness, replaced the alternator and checked the battery condition, all to no avail so far. The light is simply staying illuminated and I'm only getting ~12.5v at the battery.

 

Everything has been working perfectly for months, and then all of a sudden there is smoke, and the charge warning light wire has melted a little. I don't understand where all of the extra current would have come from?

 

Cheers again!

[KernowCooper]

Pull the plug from the rear of the alternator check the  charge light wire from the IND terminal on the alternator, check it with a voltmeter do you have 12.5v coming down this wire.

[The-Womble]

Ok, I've had a check. With the plug disconnected from the alternator I get 12v on both of the large terminals, but 0v on the smaller terminal whether the ignition is on or off. Does this tell us anything? The light on the dashboard still comes on as normal.

 

Thinking about it today, could this have been caused by the coil by any chance? The car had an electronic dizzy fitted to it a few months back (one of the ones with the black box on the side). The coil was also changed and a 12v feed taken straight from the fusebox to the coil, although the coil does not say on it if it is ballasted or not. I assume it shouldn't be?

Edited by The-Womble, 02 September 2013 - 05:33 PM.

[KernowCooper]

Yes it tells me the brown/yellow  wire to the ind terminal on the alternator is finding another earth to bring the light on other than through the diode pack, this small brown/yellow should have 12+ on the small lucar end when the ignition is on.

 

When you started up and noticed the smoke, that was being caused by a 12v current coming back up the brown/yellow from the alternator and a dead short to earth, you need a probe tester now and probe the brown/yellow and see where the ignition light is getting its earth from, as with the alternator plug out there should be no ignition light, except like in your case the ignition light has shorted to earth somewhere between the back of the dash and the alternator IND connection on the alternator

 

Nothing to do with the coil, 12v coils should have a reading of 3.5ohms on the +/- terminals and a 12v feed from the white wire on the fusebox

[The-Womble]

Ok great, thanks a lot!   I'll go and have a hunt through it now.

 

Looking at the wiring diagram, I could run a wire from the small IND spade on the alternator to the back of the charge warning light (obviously with the existing IND wire disconnected at both ends) and it should behave normally, is that right? Just as a test, not a permanent fix.

[KernowCooper]

yes thats a test, 12v in one side of the bulb from a ignition controlled feed, out on your new wire to the ind terminal which should show 12v with the ignition on, but I suspect it wont charge as the diode pace is probably toast.

[The-Womble]

I'll go and give it a shot. This is a different alternator to the one that was on it when it cooked itself, so it should be alright I hope! I'll post up the results shortly

[The-Womble]

Hooray! It's fixed! I ran a new wire from the IND spade on the alt to the charge light, but that didnt seem to work. Had a wiggle around of the connections and the light flickered on and off so I pulled the light fitment out and turns out the bulb is too small for the thread and was just kind of...rammed in there. It had worked itself loose and corroded itself to the side. Gave it a clean up and re-seated it and voila....13.8v at the battery and no light! Will get a new properly-fitting bulb tomorrow.

 

Thanks a lot for your help Kernow! Much appreciated!