Hi -

I'm trying to work out if my alternator is dead. I have an 1997 899 Cinquecento SX.

First of all, when I turn the key to acc. the battery warning light doesn't come on at all. It never has, and I assumed this was just the bulb. Anyway, it's run fine for a year like this.

However, last night when driving home the instrument lights seemed very dim, and the battery warning light came on very briefly when the revs were low.

This morning it wouldn't start (dead battery), so I get the jump leads out and fire it up. Disconnected the jump leads and put a voltmeter on the battery and it read about 12.5V, so I assume it's not charging. So far, it looks like the alternator is dead.

However, while the engine was still running, I unplugged the signal wire (at least, i think it was the signal wire - it was the thin purple one) and suddenly the battery voltage jummps up to about 14V and the revs drop a bit suggesting there is a bit of a load on the engine.
So I assume it's now charging, and I plug the signal wire back in and go for a wee drive to charge the battery up a bit.

When I get back, I put the voltmeter back on, but now with the engine running the voltage is back to 12.5V, and unplugging the signal wire has no effect any more. But the battery has definately charged up because it starts on it's own without the jump leads.

What's going on?
Is my alternator dead?
Is there a regulator I can replace seperately?
Why does my warning light never come on?
If I ground the signal wire, should the light come on?

Cheers for any suggestions -

Leo

Signal light behaviour seems right. Everything suggests that the alternator is on its last legs (should be 14.5v). Although the rectifier/regulator is, theoretically, available seperately you'll really struggle to get one. May be easier to get it rebuilt at a specialist. See if you can borrow a decent battery just to check it all out again.

Hi -

Thanks for the reply -

fingers99 said:

Signal light behaviour seems right.

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Really? I thought it should come on when you turn the key, then go out when you start it.

fingers99 said:

Everything suggests that the alternator is on its last legs (should be 14.5v). Although the rectifier/regulator is, theoretically, available seperately you'll really struggle to get one. May be easier to get it rebuilt at a specialist. See if you can borrow a decent battery just to check it all out again.

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Will try another battery. Saw an alternator on eBay for £20, so might try that.
Are they easy to swap out? (a quick search suggests it's just a case of taking the engine down a bit on a jack and pulling it out via the front wheel arch. Is that right?

Leo

LeoC said:

Really? I thought it should come on when you turn the key, then go out when you start it.



Are they easy to swap out? (a quick search suggests it's just a case of taking the engine down a bit on a jack and pulling it out via the front wheel arch. Is that right?

Leo

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Apart from that bit, which is odd!

Never done it on an 899, but should be a little easier than on an 1108.

fingers99 said:

Apart from that bit, which is odd!

Never done it on an 899, but should be a little easier than on an 1108.

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Yes, and er , no.

You need to be careful of the crank sensor bracket.

Would rather remove the crank pulley than try and remove the bracket. Its very easy to shear the wee 6mm bolt.

This rather assumes you will be changing the belt at the same time, which would be sensible.

Cheers

SPD