11 replies to this topic

[Colbs]

Evening all i started my mini up tonight for the first time in a while,after ticking over for 5 mins or so i shut the engine off and noticed the little red ignition light was still glowing,any ideas why this might be?.Upon start up the oil light and the red light went off quite rapidly as normal and all other functions worked apart from horn.Thanks all.

[bmcecosse]

Does it have a dynamo?   Did you leave it with the red light on??  

[KernowCooper]

Ignition light glowing if you have a alternator with the key turned off usually indicates a faulty diode in the alternators rectifier pack, pull the plug out of the back of the alternator and then recheck the ignition light should go out

 

Another test is with the key off probe the small terminal on the alternator with the plug in with a multi meter on DC Volts and earth and check for any voltage, key off should show no voltage.

[spaulwill]

As Dave says if a diode in the rectifier has gone you are getting a reverse feed back through the alternator. This is a repair shop job not somthing you would generally tackle yourself, somtimes cheaper to get a recon alternator.

[Colbs]

Hi folks thanks for advice i went to check the plug that goes into the alternator as suggested and have discovered all the wires leading into said plug have melted down to the inner wire having burnt right the the leccy tape and outer coating.I feel bearing in mind the main loom is attached further down i may be up s%*t creek,am i right???.I fear an incorrect battery connection has caused this :-( ?? cheers

[Dan]

  The cables for the alternator connection only run as far as the solenoid so it might not be too bad.  You need to open up a fair chunk of the loom for inspection now though.  Have you got an uprated alternator fitted?

[KernowCooper]

As Dan pointed out the 2 brown wires dont actually go that far, I'd be checking the terminals in the alternator as well, as loose terminals caould have caused it by not making a good contact under load the heat has burnt the cable. Cut the loom back and replace th 3 as required

Edited by KernowCooper, 29 July 2013 - 09:02 PM.

[Colbs]

Hi Dan i don't think it's an uprated one but can you tell me how i'd tell please.Lastnite i nipped in house for a leak and when i came back out my mate had took it upon himself to connect the battery,i noticed a smell of burning but i put that down to the grinding i'd been doing previous to going indoors.... anyhow i called him a bonehead and reconnected the battery correctly.I didnt think anymore of it so i pulled out the choke and turned the key and she fired up firstime.After 5 mins of tickover i tried lights,indicators,wipers etc snd all worked barring horn and stereo and the red light sfter switch off was also an issue.
After reading responses from the guys on here i went out to garage tonight to do as suggested and thats when i noticed the charred remains,the copper internals of the wire have almost dissolved and yet the plug that goes into alternator has not melted.Is this likely to be an auto electrician job??.cheers

[KernowCooper]

Not a problem if your OK on wiring and could be done inside a hour, just depends how you feel about replacing the wires and fitting th correct terminals

[Captain Mainwaring]

Not a problem if your OK on wiring and could be done inside a hour, just depends how you feel about replacing the wires and fitting th correct terminals

 

 

Depending on the year some vehicles were fitted with fusible links (hypalon or something like it) between starter lug and alternator - could be this has failed as a result of the reverse polarity. 
It's supposed to be practically impossible to source new links now except from scrap vehicles so you could just replace with normal stranded copper if indeed you had fusible links in the first place.

[Dan]

Hi Dan i don't think it's an uprated one but can you tell me how i'd tell please

 

 

 

  If you don't know about the car's history then check the data plate on the alternator.  Although the fusible link sounds like a more likely culprit, but you haven't said what car it is so it's hard to help much.  I don't think when the links fail there is all that much physical heat damage around them usually.

Edited by Dan, 30 July 2013 - 07:53 AM.

[Colbs]

Hi sorry yes it's a 1991 mini cooper s twin carb and i'll check the alternator this evening and see what i can learn.I think what i need to do is get the front grille removed and see from the front the extent of the damage.Im hoping if i can strip the cable back i may be able to replace like for like as some of the guys have suggested.My knowledge on electrics is generally terrible to be honest but i've just ordered haynes automotive manual to gain an insight.If i get out my depth i'll have to call on some help i think.Im hoping from what you guys are saying the damage is limited.cheers