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Charge light on BUT alternator charging well


series3100
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Ok... electrics isn't my strong point firstly...

I fitted a 200tdi into the series 3 and rewired everything so wiring wise there's nothing normal about this :unsure:. The alternator's putting out 14V but the charge light stays on... weird!?

From the ignition switch the white wire goes to (among other things) one side of the charge light than the brown/yellow wire from the alternator is going to the other side of the light. Being a light bulb it shouldn't matter what side what's attached to it should it?

I'm a bit baffled cos i thought i'd started to understand electrickery :lol:

So what stupid thing have i done this time?

Cheers, Brian

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Ok... electrics isn't my strong point firstly...

I fitted a 200tdi into the series 3 and rewired everything so wiring wise there's nothing normal about this :unsure:. The alternator's putting out 14V but the charge light stays on... weird!?

From the ignition switch the white wire goes to (among other things) one side of the charge light than the brown/yellow wire from the alternator is going to the other side of the light. Being a light bulb it shouldn't matter what side what's attached to it should it?

I'm a bit baffled cos i thought i'd started to understand electrickery :lol:

So what stupid thing have i done this time?

Cheers, Brian

Pretty sure there needs to be a diode like in this pic

ALT4.GIF

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Is it fully lit, or glowing? Does it light up when you put the ignition on, but before you start the engine?

Most likely the bulb wattage is too low, so the alternator current draw through the bulb is enough to put the light on. Try temporarily adding a second bulb wired across the first one to check.

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Doesn't matter about the diode on these - you really only need it when running EFI because the alternator will backfeed a very small current into the ignition - enough to keep and ECU 'on' and therefore your engine running! The small current isn't enough to keep the stop solenoid open on a diesel.

Could be bulb wattage, or could be a 'ked regulator in the alternator.

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It's not a glow, it's good n proper!

Engine off, ignition on - light on.

While running should I have 12v coming from the brown/yellow wire on the back of the alternator? maybe I should check that? With the ignition on and the engine off the bulb is lit and there is about 1v at the alternator... is this as it should be? I have a second alternator i could swap in but wanted to check first.

Ooh another electrickery question! My water temp gauge over reads massively, the water's at 60 degrees odd and the needle's in the red. Is this me doing something stupid again or is it just the fact it's a Britpart sender? :huh:

Brian

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Yes, that all sounds correct. Try adding another bulb in series, or changing the bulb to one from a disco.

No, your water gauge will read waaay out. You need a matched sender/gauge pair. Either use the sender from the series, or somehow bodge a disco gauge into the series. You should also be able to use a resistor of the right value to match an unmatched pair, but I've never got around to trying it.

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Yes, that all sounds correct. Try adding another bulb in series, or changing the bulb to one from a disco.

In parallel I think, rather than series, though might as well try both. But the disco one would be a better check.

If the light is full on, it's unlikely to be due to that though, I'd suspect a duff regulator.

You can often bodge the sender with one or two resistors (one series, one parallel) but it's likely you get a gauge that only reads right at two places. Done it for fuel gauges in the past, where it can be harder to change the sender. Try to use a series sender if you can though, it's likely to be much less hassle.

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In parallel I think, rather than series, though might as well try both. But the disco one would be a better check.

If the light is full on, it's unlikely to be due to that though, I'd suspect a duff regulator.

You can often bodge the sender with one or two resistors (one series, one parallel) but it's likely you get a gauge that only reads right at two places. Done it for fuel gauges in the past, where it can be harder to change the sender. Try to use a series sender if you can though, it's likely to be much less hassle.

The light is fully on good and bright so i'll try swapping out the the alternator cos i have a spare, then if that doesn't work i'll start playing with bulbs...

I fitted a series petrol sender with a thread adaptor so i'm not sure what's going on here! :ph34r:

Cheers, Brian

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I fitted a series petrol sender with a thread adaptor so i'm not sure what's going on here!

Britpart?

...Is this me doing something stupid again or is it just the fact it's a Britpart sender? :huh:

Brian

Yup :rofl: I think you may of just confirmed my suspicions...

Brian :i-m_so_happy:

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