Electrical Woes!!

[k77-widow maker]

Hows this....the car has been playing up for the last couple of days, in that in the morning the battery is as flat as a pancake, if you jump start it, it will run fine until the fans kick in and then it will die.
I have a spare battery which i fitted, and ran the car for the day without any problems, then next morning... you guessed it! the thing was flat again.

This morning i refitted the now fully charged previous battery, and have used it all day, however on the way home tonight, i noticed that the red warning light comes on, depending on revs at the time. I did notice that the light was coming on when the volt meter was sayoing it was running at about 14 volts (ish) then if you backed off the throttle, the light went out. Soon after the light stayed on very dimly no matter what the revs were.

I'm guessing that the much mentioned 100A fuse underneath the car must be ok, else the light will be on all the time????

Or am i looking at a new alternator? What sort of tests should i be doing??

[Ballistic Banana]

probably like you said the fuse,but hows the fan belt? may be slack.

just a thought

BB

[k77-widow maker]

thanks for that, the belt is quite new, and feels tight....if it was loose then it would squeel??

[andy43]

As far as I'm aware, and I could be wrong ?? the precats don't have the 100A fuse - not noticed one under mine anyway. Could possibly be a dodgy alternator diode pack - had it on mine - it's fine when the engines running, but as soon as you switch off, the battery drains through the faulty diodes - killed my battery twice over nights - ended up with a recon alternator. Testing it might be tricky without the right equipment. No idea why the fans could stall the engine, unless they just take that little bit too much extra current from a freshly drained battery?

>> Edited by andy43 on Friday 3rd September 23:00

[simon.b]

Check that fuse, don’t just look at it, remove it. Mine was in two pieces but looked OK.

Cheers,

Simon.

[heliox]

there isnt a linked fuse on early models.

as andy43 has sugested, check alternator for faults.

secondly check fuel pump relays arent draining your power as they can do when the alternator is faulty.

h

[stesrg]

Almost certain its your alternator diodes, if you remove it take it to an autoelectrition and he will test it for you.
Steve....

[k77-widow maker]

Cheers Guys, it's looking like the alternator is the guilty party then, then fuel pump relays were both changed a few weeks ago, so i'm going to hope that they are ok.
The diode problem does seem to be the logigal answer, BUT didn't i read somewhere that the red light normally stays on after the engine is switched off, if the diode is at fault?

[shpub]

You can get all sort of faults and symptoms including a very bizarre let's pulse the lights failure mode. worth chceking the fan belt but I suspect that the alternator has given up the ghost. As been said, an alternator guy shoud be able to sort it out for you.

[k77-widow maker]

shpub said:

You can get all sort of faults and symptoms including a very bizarre let's pulse the lights failure mode. worth chceking the fan belt but I suspect that the alternator has given up the ghost. As been said, an alternator guy shoud be able to sort it out for you.

I think the fan belt is ok, there is no problem with the cooling, esp being sat on the m25 for 20 mins yesterday, at 1300hrs....i'm still a nice salmon pink too!

[Northern_Paul]

k77-widow maker said:

BUT didn't i read somewhere that the red light normally stays on after the engine is switched off, if the diode is at fault?

Drove mine for the 1st time in 2 years yesterday to the Auto Electrician 4 miles. Lots of switching the ignition ON, but not firing up the engine and my red led would stay ON after I switched it OFF (only way to extinguish it was to turn the engine over and then OFF).

Do you think I've got a knackered diode pack?? Can you elaborate??

[andy43]

If its any help, I had no warning lights up when mine went. You can also upgrade the alternator to a higher ampage/amperage/whatever/bigger one... link to when I had problems....
[url]www.pistonheads.com/gassing/topic.asp?f=9&h=&t=39876[/url]
why I can't get a proper link to appear I've no idea...

[Northern_Paul]

I've took mine to get checked, he also reckons that the diodes are gone - won't know until Monday lunchtime.

If it's expensive I think I'll upgrade as per your link.........Thanks.

[k77-widow maker]

It was the alternator, something inside must have been causing a drain, Got a new alternator from a land rover spares place in Cambridge £57 inc vat.

Once again a happy chappy, and the griff is no longer under threat of dealing sold