bonjour a tous,
sur ma b de 1977, le voyant de charge s'allume, mais après vérification la batterie charge bien , ce n'est donc pas l'alternateur qu'est ce que cela peut être?
merci de vos lumières
Patrick
voyant de charge allumé
-
temp5
Le voyant est alimenté par un + batterie venant du contact, par contre le - est relié à l'alternateur. Si celui-ci NE fournit PAS de +12V ---> 0V = masse ---> le voyant s'allume.
Si l'alternateur fourni bien du +12V le voyant se retrouve entre +12V et +12V et s'éteind.
Alors verifie la continuité de la liaison à l'alternateur (pb de mauvais contact des causses peut être)
NB : Sans vouloir être trop défêtiste, je soupçonnerai plutôt un PB d'alternateur.
Si l'alternateur fourni bien du +12V le voyant se retrouve entre +12V et +12V et s'éteind.
Alors verifie la continuité de la liaison à l'alternateur (pb de mauvais contact des causses peut être)
NB : Sans vouloir être trop défêtiste, je soupçonnerai plutôt un PB d'alternateur.
-
Renou-Invité
-
Renou-Invité
-
Renou-Invité
Bonjour,
Je voulais dire: retirer le voyant de son logement. Mais sur une B de 1977, il doit y avoir
des diodes sur le circuit électrique et les diodes ça claque. Tu peux trouver les schémas électriques sur ce lien:
"http://www.mgb-stuff.org.uk/s_charge.htm" Sans ce support, il est difficile de faire un diagnostique précis. Je te fais suivre un troubleshoot guide pour analyser ton probléme:
It glows all the time
This usually means the dynamo/alternator is not charging, although it could be a fault in the warning light circuit. Check the system voltage with the engine running at a fast idle.
If you see at least 14v then the system is charging. Use "It doesn't glow when it should" above to check the warning light circuit, making sure it isn't grounding at any point and is connected to where it should be.
If you only see 12v then the system isn't charging:
Dynamo: Test the dynamo by removing both connections and bridging the two spades on the dynamo. Connect a voltmeter between here and ground and start the engine DO NOT REV IT. Slowly increase the engine speed whilst watching the voltmeter. Do not allow the voltmeter to reach 20v, this should happen before the engine reaches 1000 rpm.
If the voltmeter reads 0.5v to 1v then the field winding may be faulty.
If the voltmeter reads 4 to 5 volts the armature winding may be faulty.
If the correct voltage is obtained the control box may be faulty.
Control Box: The control box monitors the output voltage from the dynamo and when this has reached 12.7v to 13.3v the cut-out relay operates connecting the dynamo output to the battery. The other two relays are the current regulator to stop an excessive load damaging the dynamo, and a voltage regulator to stop overcharging the battery. Both work by opening a contact when they operate introducing a series resistance into the field circuit, so reducing the excitation and hence the output current/voltage.
Alternator:
Use "It doesn't glow when it should" above to check the warning light circuit, making sure it isn't grounding anywhere, and making sure it does get back to the alternator.
Check the voltage on the thick brown(s) at the alternator plug (remove the cap but leave the plug plugged in). If this is also 12v then replace the alternator. If you see higher than this then a break in the thick brown between the alternator and where it picks up the heavy current cable is indicated. The thick brown connects to the heavy current cable either at the solenoid, or at a copper stud under the toe board on the RHS. It doesn't glow when it should
Your ignition warning light should always glow when you first turn on the ignition, before you have started the engine. If it doesn't, and at some point in the future your dynamo or alternator stops charging, you are unlikely to know about it until the car conks out and you are stranded. At which point you will probably blame Lucas instead of yourself.
Check that with the ignition on (the engine needn't be running) you have 12v on the white at the warning light lamp-holder.
Check that this 12v flows through the bulb and appears on the brown/yellow at the lamp-holder.
Check that the body of the lamp-holder is not in contact with a ground when it is plugged into the tach.
Check that the 12v reaches the control box/alternator on the brown/yellow.
If you have any doubts about this next bit, don't do it: Connect the (unplugged) brown/yellow at the control box or alternator to ground and the warning lamp should light. DON'T connect the thick brown(s) in the alternator plug to ground.
If you have got this far you should have found any faults in the warning light circuit itself. If the warning lamp glows when you ground the brown/yellow but doesn't glow when connected back up to the control box/alternator:
Dynamo: The warning light terminal is connected to the 'D' terminal on the control box, which has another brown/yellow to the output terminal on the dynamo. With both brown/yellow wires connected back up at the control box, grounding the brown/yellow at the dynamo should light the warning lamp. If this works, but the lamp doesn't light with the wire connected back up to the dynamo, then you have an internal disconnection in the dynamo - follow the circuit through the brushes and the commutator to the body of the dynamo.
Alternator: There may be a simple internal disconnection. If you know what you are doing it might be worth looking for it and trying to fix it, otherwise replace the alternator.
Il faut absolument savoir qulles sont les spec. du véhicule.
Cdt.
Je voulais dire: retirer le voyant de son logement. Mais sur une B de 1977, il doit y avoir
des diodes sur le circuit électrique et les diodes ça claque. Tu peux trouver les schémas électriques sur ce lien:
"http://www.mgb-stuff.org.uk/s_charge.htm" Sans ce support, il est difficile de faire un diagnostique précis. Je te fais suivre un troubleshoot guide pour analyser ton probléme:
It glows all the time
This usually means the dynamo/alternator is not charging, although it could be a fault in the warning light circuit. Check the system voltage with the engine running at a fast idle.
If you see at least 14v then the system is charging. Use "It doesn't glow when it should" above to check the warning light circuit, making sure it isn't grounding at any point and is connected to where it should be.
If you only see 12v then the system isn't charging:
Dynamo: Test the dynamo by removing both connections and bridging the two spades on the dynamo. Connect a voltmeter between here and ground and start the engine DO NOT REV IT. Slowly increase the engine speed whilst watching the voltmeter. Do not allow the voltmeter to reach 20v, this should happen before the engine reaches 1000 rpm.
If the voltmeter reads 0.5v to 1v then the field winding may be faulty.
If the voltmeter reads 4 to 5 volts the armature winding may be faulty.
If the correct voltage is obtained the control box may be faulty.
Control Box: The control box monitors the output voltage from the dynamo and when this has reached 12.7v to 13.3v the cut-out relay operates connecting the dynamo output to the battery. The other two relays are the current regulator to stop an excessive load damaging the dynamo, and a voltage regulator to stop overcharging the battery. Both work by opening a contact when they operate introducing a series resistance into the field circuit, so reducing the excitation and hence the output current/voltage.
Alternator:
Use "It doesn't glow when it should" above to check the warning light circuit, making sure it isn't grounding anywhere, and making sure it does get back to the alternator.
Check the voltage on the thick brown(s) at the alternator plug (remove the cap but leave the plug plugged in). If this is also 12v then replace the alternator. If you see higher than this then a break in the thick brown between the alternator and where it picks up the heavy current cable is indicated. The thick brown connects to the heavy current cable either at the solenoid, or at a copper stud under the toe board on the RHS. It doesn't glow when it should
Your ignition warning light should always glow when you first turn on the ignition, before you have started the engine. If it doesn't, and at some point in the future your dynamo or alternator stops charging, you are unlikely to know about it until the car conks out and you are stranded. At which point you will probably blame Lucas instead of yourself.
Check that with the ignition on (the engine needn't be running) you have 12v on the white at the warning light lamp-holder.
Check that this 12v flows through the bulb and appears on the brown/yellow at the lamp-holder.
Check that the body of the lamp-holder is not in contact with a ground when it is plugged into the tach.
Check that the 12v reaches the control box/alternator on the brown/yellow.
If you have any doubts about this next bit, don't do it: Connect the (unplugged) brown/yellow at the control box or alternator to ground and the warning lamp should light. DON'T connect the thick brown(s) in the alternator plug to ground.
If you have got this far you should have found any faults in the warning light circuit itself. If the warning lamp glows when you ground the brown/yellow but doesn't glow when connected back up to the control box/alternator:
Dynamo: The warning light terminal is connected to the 'D' terminal on the control box, which has another brown/yellow to the output terminal on the dynamo. With both brown/yellow wires connected back up at the control box, grounding the brown/yellow at the dynamo should light the warning lamp. If this works, but the lamp doesn't light with the wire connected back up to the dynamo, then you have an internal disconnection in the dynamo - follow the circuit through the brushes and the commutator to the body of the dynamo.
Alternator: There may be a simple internal disconnection. If you know what you are doing it might be worth looking for it and trying to fix it, otherwise replace the alternator.
Il faut absolument savoir qulles sont les spec. du véhicule.
Cdt.
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