ClassicRangieLeigh Posted January 24, 2014 Share Posted January 24, 2014 Hi all, Just recently I've had a random bout of electrical faults. This week alone, a hundred yards from work and in the pouring rain the sunroof opened all by itself, completely wide open. So armed with a screwdriver I wound it back shut manually and unplugged it. Then, yesterday the battery light was on at first start up and the engine was running like a sack of carp. So obviously the first thing I though was the alternator. However, after limping it home and getting the multimeter on it there was 14.2 Volts there. All the wires are on the alternator fine, and I haven't had chance to dig out the wiring diagrams to chase it round yet. To be fair, my old Classic has been stood for about 2 weeks and has got damp inside, but still, there's no need for this bad behaviour!!! Quote Link to comment Share on other sites More sharing options...
Highway_Star Posted January 25, 2014 Share Posted January 25, 2014 Does the light go out with the ignition off? If not, then you've a failed diode in the alternator. You can replace the entire diode pack. At the age of these cars now, it's worth giving the alty a good clean, some lube in the bearings and treating it to new brushes if nothing else. Quote Link to comment Share on other sites More sharing options...
ClassicRangieLeigh Posted January 25, 2014 Author Share Posted January 25, 2014 The alternator was reconditioned about 8 months ago, so I'm thinking it's something else. Like I say, it's making 14.2 volts at the battery. Also, after a half an hour drive the alternator is still only warm, not hot, so there's no big friction issues from bearings etc. The light goes out when the ignition is turned off. I've read the wiring diagram, and I've got it down it the battery light wire rubbing on an earth somewhere, however, I've not tested this yet. Quote Link to comment Share on other sites More sharing options...
DaveSIIA Posted January 25, 2014 Share Posted January 25, 2014 Can you disconnect the wire for the warning light from the back of the alternator to isolate a wiring fault? Switch the ignition on (no need to start the engine)- warning light should be off (if on then suspect a short somewhere in the loom). Earth the warning light cable at the alternator end and the warning light should come on. If you can control the warning light this way then the fault is in the alternator. Quote Link to comment Share on other sites More sharing options...
ClassicRangieLeigh Posted January 25, 2014 Author Share Posted January 25, 2014 Can you disconnect the wire for the warning light from the back of the alternator to isolate a wiring fault? Switch the ignition on (no need to start the engine)- warning light should be off (if on then suspect a short somewhere in the loom). Earth the warning light cable at the alternator end and the warning light should come on. If you can control the warning light this way then the fault is in the alternator.This sounds a good way to diagnose it, I'll have a go tomorrow (Sunday). Cheers DaveSIIA Quote Link to comment Share on other sites More sharing options...
ClassicRangieLeigh Posted February 10, 2014 Author Share Posted February 10, 2014 How do? Right, managed to find time to have a go at this over the weekend. Removed the little brown and yellow wire from the alternator and the light went out, which means everything is pointing at the alternator being at fault. It was only reconditioned last year as well!!! I'll take it back and see what comes of it. Thanks for your help so far folks. Cheers, Leigh. Quote Link to comment Share on other sites More sharing options...
Snagger Posted February 11, 2014 Share Posted February 11, 2014 There's more con than re in recon. I don't think an open sunroof should let water affect anything other than the switches on the centre console, ie. the window switches (and heated seats, if fitted) - I can't imagine the airbag system being affected either as the ECUs would be shielded by the console and drips onto the ECUS are unlikely. Quote Link to comment Share on other sites More sharing options...
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