Dimming/flickering lights

Hi

Haven't been on for a while, i've just bought a new disco and there are a couple of problems i want to get sorted.

All my lights seem to flicker, i've put a multimeter across the battery with it running and i was getting a reading of about 14.8/9 volts so can't see it being the alternater.

I've cleaned up the earth points from the battery negative cable and it's still doing it.

Has anyone got any idea's?

My rev counter seems to go through a phase of doing what it wants just going all over the place but no fluctuation of the actual revs. Just the needle go's up and down, i wouldn't of thought there related and more likely just a loose cable.

Thanks

Check the wiring behind the lamps and the 3 pin headlamp connectore, they have a habit of melting and/or falling to bits.
The revcounter is driven off the alternator so check the connections there.

hughesy said:

Check the wiring behind the lamps and the 3 pin headlamp connectore, they have a habit of melting and/or falling to bits.
The revcounter is driven off the alternator so check the connections there.

Click to expand...

would the headlamp wiring affect all the lights to dimmer inc interior and even the yellow fuel light!!

ok i'll check out the connections on the alternator, it doesn't look that old so they might be loose. Thanks for that.

it could be that the brushes in the alternator are worn.your meter would still give a reading saying your alt is charging but it could be "pulsing" rather than having a steady charge but failing that it could be just down to earth problems!

If it's all the lights it's likely your earth is no good and will probably fail altogether at some point. Check any earthing wires best to take them off, clean and re fit.

Ok thanks for your help,

I'll start with the earth wire's and if i don't get much luck from that, then alternator cause i'm pretty sure the alternators reasonably new as it's pretty clean.

Thanks

Which model of Discovery?

Be not so sure the alternator is OK yet.

14.8 to 14.9 volts is quite a lot. Usually it should not exceed a nominal 13.8 for any length of time.

CharlesY

I did find a wire that didn't have a brilliant connection on the back of the alternator, The lights are loads better not sure if it's spot on now or whether i'm looking at them too closely!!! And abit early to tell if it's sorted the rev counter as it was tempremental and didn't do it all the time.

Oh i thought it was around 14.6 with it running?
So if it is high, what's likely to be coursing that?

Thanks

nicedayforit said:

Which model of Discovery?

Click to expand...

It's a 98 300tdi disco

The wire that was questionable is probably the feeder to the alt's field windings.
That may be why the previous owner replaced alt.

It's poss that the internal voltage regulator is damaged but, it won't hurt to drive it.
(of course it's not me)

the 14.8-9 volts is on the high side, for sure -- it will boil the electrolyte out of your battery alot sooner than 13.6-14.3volts will

I'd try revving 'er up while reading the voltage to see if it holds @ 14.8

luck,greg

your alternator is overcharging if anything over 14volts as it should only be 13.8v.eventually you will fry your battery!

try reading this http://www.landyzone.co.uk/lz/f38/alternator-troubleshooting-75224.html

Check the resistance between the body earth and alternator bracket.

If the earth is a bit on the poor side then it is unlikely the engine would crank and start in the first place i.e. the starter would need more 'earth' if you like than the lights. Do the lights flicker with the engine off?

Is the flicker constant (if that makes sense) for example does the frequency of the flicker change with engine revs? I have no doubt you have checked the drive belt for areas off damage so the alternator is suspect, add this to the fact you have such a high voltage reading.

As mentioned the rev counter takes it's feed from the alternator, this needs a 'steady' feed to be accurate. The rectifier (AC to DC) is normaly the issue with this kind of fault bearing in mind that AC 'pulses'.

regards

Dave