Author Topic: Generator charge warning light not coming on  (Read 419 times)

Offline speedyg

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Generator charge warning light not coming on
« on: April 25, 2021, 01:10:47 PM »
1983 Le Mans III. Just got the bike out of winter storage and noticed that the generator light is off when turning on the ignition switch. Engine not running.
Battery is good. 12.75V
I thought it might be the lamp so got into the back of the console. All other lights are good and checked the voltage on the red daisy chain connection to the other lamps. All is good.
I have continuity on the sky blue wire from the lamp to the 61 terminal (difficult to read on the schematic).
If I fire up the engine, still no light at low idle where it usually comes on.
Everything was fine prior to laying up for the winter.
I do have a diode test function on my fluke multi meter.
Could the problem be the rectifier or voltage regulator?

Online Tom

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Re: Generator charge warning light not coming on
« Reply #1 on: April 25, 2021, 01:15:45 PM »
Did you check continuity on the bulb? 
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Online ohiorider

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Re: Generator charge warning light not coming on
« Reply #2 on: April 25, 2021, 01:33:44 PM »
I looked up 'alternator' for 1984 Moto Guzzi.  It appears to be identical to the Bosch alternator BMW airheads used for several years.  I have documentation from Rick Jones at Motorrad Elektrik that discusses the lamp status and potential electrical problems I can send you if you think it'd be useful.  When working correctly, does the light come on when ignition is switched on, then go out once started.  Is the alternator outputting power?

Bob
« Last Edit: April 25, 2021, 01:35:44 PM by ohiorider »
Main ride:  2008 Guzzi 1200 Sport (sold July 2020)
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Online Tom

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Re: Generator charge warning light not coming on
« Reply #3 on: April 25, 2021, 03:21:59 PM »
The pins are small on the bulb.  Maybe corrosion on them.  If the bike is stored with battery connected and on a charger during the off season.  Check the where it clips in to the socket.  BTDT.
« Last Edit: April 25, 2021, 03:23:30 PM by Tom »
From the Deep Deep South out in left field.  There are no stupid questions.  There are however stupid people asking questions.  🤣, this includes me.  😉

Wildgoose Chase Moto Guzzi

Re: Generator charge warning light not coming on
« Reply #3 on: April 25, 2021, 03:21:59 PM »

Offline speedyg

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Re: Generator charge warning light not coming on
« Reply #4 on: April 25, 2021, 03:30:25 PM »
I did check the lamp with a ohmmeter it was good. I also tried the lamp in another socket and it was good.
I did more checks and found that the plug in connector had somehow pulled out of the regulator receptacle.
Reconnected and light comes on. Fire the engine and light on a low idle and goes out as you come off idle as it should be.
Thanks for your inputs. Appreciate.

Online Tom

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Re: Generator charge warning light not coming on
« Reply #5 on: April 25, 2021, 04:15:54 PM »
Hey.....cool.   :thumb: 
From the Deep Deep South out in left field.  There are no stupid questions.  There are however stupid people asking questions.  🤣, this includes me.  😉

Offline n3303j

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Re: Generator charge warning light not coming on
« Reply #6 on: April 25, 2021, 05:38:59 PM »
If it's like the BMW Bosch a hung (or worn) alternator brush will disconnect the indicator lamp.
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