Mavic82 Posted February 28, 2015 Share Posted February 28, 2015 Triggers broom has been upgraded from a Lucas brick alternator to a nice new Denso unit.the Lucas had two +ve battery connections and the alternator warning light. This worked fine and the light would go out above 600rpm.wiring the Denso seemed straight forward, the +ve connections both connected to the main battery post. The warning lamp wire connected to the L terminal and a new switched live connected to LG. Started the car and it all runs great, charging at a healthy 14.5 volts.but the warning light does not go off. Any one else done this conversion and had and solved the issue? Having searched there seem to be similar issues but no solutions.just to add it is an LED warning light, with a resistor but worked fine before.thanks Link to comment Share on other sites More sharing options...
Klunk Posted February 28, 2015 Share Posted February 28, 2015 Quick recap on the theory: When the ignition is on, but engine off, 12v is supplied to the dash warning light from the loom (green wire). 0v is supplied from the alternator (brown/yellow wire) so there is a potential difference of 12v-0v = 12v and the LED lights. With the engine running 12v is supplied from the alternator. As a result the potential difference is 12v-12v = 0v and the LED goes out.With that in mind:To check the warning light wiring. Remove the brown/yellow warning light wire from the alternator. With the ignition on, first 'earth' the wire. The warning LED should light. With the ignition still on, apply 12v to the wire (touch onto the main alternator post). The warning LED should go out. If it doesn't the issue is in the warning lamp wiring.If all is okay, leave the brown/yellow wire disconnected from the alternator and do the following. With the ignition on, but engine not running, you should get a voltmeter reading of 0v on the alternator's 'L' pin. Next start the engine, rev it, then check again. It should now be 12v. If this isn't the case it would suggest there's an issue with the lamp feed on the alternator. Link to comment Share on other sites More sharing options...
Mavic82 Posted February 28, 2015 Author Share Posted February 28, 2015 That's a good diagnosis plan Klunk, thanks.the alternator is producing 12v as I use this to also power my DRL's but the wiring I suppose could be the issue having pulled everything apart. Link to comment Share on other sites More sharing options...
Klunk Posted February 28, 2015 Share Posted February 28, 2015 Bear in mind it is possible for the main alternator post feed to be ok but the lamp (L) feed not to be Link to comment Share on other sites More sharing options...
Mavic82 Posted March 1, 2015 Author Share Posted March 1, 2015 One would hope not with a brand new unit! Link to comment Share on other sites More sharing options...
Jochen Posted March 1, 2015 Share Posted March 1, 2015 /sites/default/files/images/users/1211/image_7.jpg Link to comment Share on other sites More sharing options...
Mavic82 Posted March 1, 2015 Author Share Posted March 1, 2015 Pin L does not generate 12v. So either the unit is faulty or I have blown something. Not sure how I could have done that but seems odd for a new unit to be faulty.i do power some DRLs off this connection but it never bothered the previous alternator.very odd. Link to comment Share on other sites More sharing options...
Klunk Posted March 1, 2015 Share Posted March 1, 2015 Strange . Out of interest, where did you take the switched live from? Have you checked that is working as expected? Link to comment Share on other sites More sharing options...
Mavic82 Posted March 1, 2015 Author Share Posted March 1, 2015 Yes the switched live works fine and the alternator does charge ok.the feed comes off the live switched feed to the rad fan. Link to comment Share on other sites More sharing options...
Klunk Posted March 1, 2015 Share Posted March 1, 2015 Humour me with this one...In case I'm wrong about checking the voltage reading at the 'L' pin, Remove the warning lamp wire from the alternator again and rig up a separate filament bulb between the battery +ve and 'L'. See if that goes out when running. Just trying to eliminate the LED aspect.As you say there are loads of incidences of this on the internet which leads me to think it's a foible rather than fault.Do you have the exact model number of your alternator? Link to comment Share on other sites More sharing options...
Mavic82 Posted March 1, 2015 Author Share Posted March 1, 2015 Klunk,the alternator is now back off the car, but I was using a DVM between a known good and tested earth and pin L. Part number is 16241-64012. Link to comment Share on other sites More sharing options...
Klunk Posted March 1, 2015 Share Posted March 1, 2015 Sorry, I wasn't questioning your method of testing. Rather, mine. I was wondering, if 'L' doesn't 'see' ~12v from the warning lamp on start up, does it decide not to switch from 0v to 12v? You would think the switched +ve would be this trigger but....The use of a filament lamp was to keep the ~12v at 'L' whilst eliminating the LED playing any part in the problem.Mine came off a Daihatsu Charade and had a multigroove pulley but pins looked the same. Your number cross references with a Daihatsu Cuore so probably the same internally. Mine worked as per your set up with an LED light, but I used an unfused switched live (white wire). I no longer have the car hence my haziness Link to comment Share on other sites More sharing options...
Mavic82 Posted March 1, 2015 Author Share Posted March 1, 2015 I see your point. I assumed that the power at L would not occur until the alternator is running and generating current rather than being triggered by the switched live. As you say the alternative is that it switches to earth, simply making or breaking a circuit. If that is the case the warning light will need a complete rewire which is a pain. Finding an alternate alternator would be a better option.thanks Link to comment Share on other sites More sharing options...
Klunk Posted March 1, 2015 Share Posted March 1, 2015 Useful info and better explanation of my point in the second paragraph here . Might be worth throwing it back on again and trying the bulb before you ditch it? Link to comment Share on other sites More sharing options...
Mavic82 Posted March 1, 2015 Author Share Posted March 1, 2015 Been thinking, if it does switch to earth, ie earth when the engine is off and connection broken when running the original charge light would still work as it would have no earth to light the light. I however added the DRLs giving a, all be it poor, link to earth permenantly. Fine if the alt generates 12 v not if it switches earth.will have to find out.i don't think the info you linked to applies, my switched live ignites the field and the alt charges fine. It is just the light. Link to comment Share on other sites More sharing options...
Mavic82 Posted March 3, 2015 Author Share Posted March 3, 2015 Update,having now now talked to the supplier they have confirmed that the L terminal is a switched earth and not a 0-12v output.easy switch to wiring to sort. Now just gut remake my push I pressed out thinking I would be sending it back :-( Link to comment Share on other sites More sharing options...
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