Battery light on dash staying on

im just going to get a patrol one before i do my drive back to nsw,till then shell be fine,or if i get bored ill recondition it myself

Why would it have anything to do with the diodes or the regulator if it starts working after he revs it? I think it's mostly likely worn brushes. If u have a few days when u don't need the car pull it out and check them yourself.

Matty450 do you know how an alternator works? it could be worn brushes, the slipring is nearly worn out, regulator, diodes, loose terminal, bad connection.
you could pull the alternator off and pull it apart and break the brushes if ur not careful. has anybody on the forum actually rebuilt an alternator?

Placey001 said:

Matty450 do you know how an alternator works? it could be worn brushes, the slipring is nearly worn out, regulator, diodes, loose terminal, bad connection.
you could pull the alternator off and pull it apart and break the brushes if ur not careful. has anybody on the forum actually rebuilt an alternator?

Click to expand...

Probably 200 maybe 300 of them. Ranging from cars to buses and trucks.
In short, yes, I have

FatBoy89 said:

Probably 200 maybe 300 of them. Ranging from cars to buses and trucks.

Click to expand...

But you don't like to brag

my appologies to those members that have rebuilt an alternator. i have too, many times and on various different vehicles as its part of my job.

if the exiter diodes are gone, or there is a bad connection inside the alternator preventing power or earth getting to the rotor, the alternator will still charge, and put the light out, if there is some residual magnetism in the rotor and you give it a rev.

KraftyPg said:

But you don't like to brag

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I thought everyone in the universe should know. Just incase

I feel better for knowing.

I feel better for letting you know

I have also rebuilt alternators before placey as I am an auto electrician. All I was saying is that i am 99% sure that it wouldn't be the exciter diodes or regulator for the following reasons.
1 it is very unlikely that the diodes would be causing an intermittent fault as they are solid state electrical components that will almost always open circuit if there is an issue, in which case the rotor wouldn't be excited at all from the battery and the residual magnetism wouldn't be enough for him to run the car very far at all.
And 2, the regulator is doing its job as it is charging his car at the correct voltage which I think is enough evidence to say its ok lol

if its a d40 they come with a clutch pulley on the alternator and may not be spinning the alt fully

Hi, we have the same issue on our D22, the light goes out after 1500RPM but we checked the charge rate and it sits at about 11.8V DC regardless of revs. I was told the belt could be loose, seems like a common problem though. someone advise if they believe it could be the alternator going and how to diagnose if the alternator isnt pumping enough power out?

If you are only getting 11.8 the alternator isn't putting any charge out. Check the fuses first, including fusible links, if they are OK it is either the brushes or the diode pack in the alternator. The brushes are easy to replace, the diode pack not so much. If you're not confident doing it yourself you can either take the car to an auto electrician or just pull the alternator out yourself and take it in for them to check and repair.

If the belt wasn't tight enough generally you would hear it squealing as the alternator loads it up, but that's not to say you shouldn't check it.

If it was the belts the charge light would stay on even at high revs..?

FIX FIX FIX....DO NOT REPLACE YOUR ALTERNATORS....This fault is common on D22, it is a high resistance within the instrument cluster charging circuit, lamp stays on and doesnt charge until revs raised. Easy way to confirm- Connect a test lamp between the battery and pin 3(Y/B wire) on the alternator when the fault occurs, the alternator will immediately start charging. . Then get your instrument cluster repaired. You can thank me later..

Can confirm comments of seventies47. Replaced my instrument cluster and problem gone. Tried everything else first to no avail.

Seventies 47,
Thanks for the info. I have the same problem of battery light staying on

until I give the engine a rev. It then goes out and alternator starts charging. Did you

find out exactly where the high resistance in was in the cluster? Thanks

check the terminals, the stock ones are crap.

Thanks Baylock,
But it is not the terminals. It is either the alternator or as
been suggested before. ie the instrument cluster.

just adding that mine does the same behaviour (red stays on till 1500rpm). never had an issue starting, and no other signs of a problem. Done it for the whole 6 months i have owned it.

if it wont start one day, ill get a patrol alt but until then ill just keep on going