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Ludders

Mi16 Not Charging At Low Revs

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Ludders

Hi everybody,

 

My newly rebuilt 205 MI16 has some strange charging behaviour. Please bear in mind my mechanical knowledge is very limited!

 

When first started and driven I notice the lights (exterior & interior) are very dim. If you give it some decent acceleration at about 3-3500 rpm everything brightens up and then I don't have a problem again even at low revs. You do have to accelerate quite hard to get it to wake up though.

 

I had a quick look under the bonnet, along the fuel rail there are two earth points, one fitted nicely and the others bolt is missing and so it is not earthing. I asked the garage I have it booked into it if this could be the problem and whilst they will fit it properly they said it is unlikely to be causing this problem.

 

This is a bit of a nightmare as the battery drains quite quickly and first thing in the morning I'm stuck in traffic and don't really want to be racing my cold engine.

 

Any advice would be very highly appreciated.

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pa402

Mine used to do this, just a 1.9 though. Battery wouldnt charge properly until revved over 3k.

 

Mine was due to the wire that should be attached to the alternator not being attached. Reattached the wire and back to normal.

 

Might be this.

 

Paul

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Tom Fenton

Yep, signal wire has either dropped off, or the brown plug is corroded to hell meaning there is no connection back to the loom. If you sort this out it will charge normally.

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Ludders

Thanks for the info. Will check this tonight and let you know.

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Peetypug

if that doesnt solve it, make sure it aint the dash bulb that has blown as this also stops the initial 12v needed getting to the alternator

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Ludders

The dash bulb? Sorry I don't totally understand. A blown bulb in the dash can stop the alternator charging? There are a few bulbs blown in the dash that I haven't got round to changing yet, am I being dumb? Also if this wire has become disconnected from the alternator will it be fairly easy to see and reconnect? Thanks

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C_W

Mine used to do this too, all wiring was ok and it was only cured when I fitted a new alternator.

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Ludders

The alternator is new so I'm assuming it's not faulty. . .

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bondo
The alternator is new so I'm assuming it's not faulty. . .

 

It really does sound like a problem with the exciter circuit. Alternators don't produce current on their own as they don't have permanent magnets in them. Consequently they need a power feed from the battery. This is connected to your dash light which will go out if the alternator is charging.

 

They will 'self excite' over about 3000 revs and carry on until you turn the car off again.

 

So you see your problem points to a fault with that circuit. Probably just a duff connection.

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Ludders

Thanks everybody. It goes into the garage tomorrow for a new steering rack so hopefully this charging problem should be an easy fix.

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Peetypug

this is straight out of the haynes

 

1 If the ignition warning light fails to illuminate

when the ignition is switched on, first check

the alternator wiring connections for security.

If satisfactory, check that the warning light

bulb has not blown, and that the bulbholder is

secure in its location in the instrument panel.

If the light still fails to illuminate, check the

continuity of the warning light feed wire from

the alternator to the bulbholder. If all is

satisfactory, the alternator is at fault and

should be renewed or taken to an autoelectrician

for testing and repair.

2 If the ignition warning light illuminates when

the engine is running, stop the engine and

check that the drivebelt is correctly tensioned

(see Chapter 1) and that the alternator

connections are secure. If all is so far

satisfactory, have the alternator checked by

an auto-electrician for testing and repair.

3 If the alternator output is suspect even

though the warning light functions correctly,

the regulated voltage may be checked as

follows.

4 Connect a voltmeter across the battery

terminals and start the engine.

5 Increase the engine speed until the

voltmeter reading remains steady; the reading

should be approximately 12 to 13 volts, and

no more than 14 volts.

6 Switch on as many electrical accessories

(eg, the headlights, heated rear window and

heater blower) as possible, and check that the

alternator maintains the regulated voltage at

around 13 to 14 volts.

7 If the regulated voltage is not as stated, the

fault may be due to worn brushes, weak brush

springs, a faulty voltage regulator, a faulty

diode, a severed phase winding or worn or

damaged slip rings. The alternator should be

renewed or taken to an auto-electrician for

testing and repair.

 

cant find a pic of the dash

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