Continual beep till 2000+ revs

[Tonka]

Hi there. I recently replaced my alternator as it was diagnosed as duff, with a new one. Happy days.

A couple of weeks ago, I started getting a continual beep from the dashboard until I get the engine over 2000-2500 revs. I've already searched on here and mostly it's a case of tightening the belts and it should go away. Well, I've just finished removing most of the skin from my right forearm doing that and it's still beeping.

What else should I look at? I have a multimeter and I'm not afraid to use it, I just need a bit of direction!

Many thanks.

[NiftyNev]

Connect multimeter to battery terminals and see how much voltage the alternator is producing at idle and the 2 - 2 1/2K revs.

Nev.

[Tonka]

Thanks Nev, yes I will do some testing today as I have time.

[Tonka]

Voltage over the battery terminals is 12.4v engine off.
Voltage with engine idle is 11.93v - so not enough obviously.

Now to figure out what's up......
I'm beginning to wonder whether I needed to replace my old alternator in the first place

And then it started to rain and I've had to give up!!

[Tonka]

Any ideas?

Well I've been poking around most of the afternoon.....

I've tightened the alternator belts, that's made no difference but how tight should they be?

The lights and alarm still go out at about 2200-2500 revs, at which point a current flows through the "charge" fuse mounted on the o/s inner wing. Up until then nothing.

Is there anything else in the circuit I should be checking? I read on here somewhere that it's possible the glow plugs could be permanently on, but I can't see how that would explain the jump up when revs increase.

By the way, does anyone know what the relay marked "Head" in the fuse box on the o/s inner wing does?

EDIT: How do I make absolutely certain it's the alternator at fault here? Whys is it not putting out enough charge at lower revs - does that mean it's the voltage regulator within the alternator or could it be a problem with the car's electrics?

Thanks for any input.

[Tonka]

Voltage readings....

Well, the batteries start off at 12.34 volts

Then when started and idling 11.89v

Then when revved to the alarm going off around 2500 revs, still 11.89v

Eventually this improves to 12.10v

EDIT: To test the Alternator as instructed in the Haynes manual you disconnect the Main cable from the alternator and connect an ammeter in circuit, but beither of my multimeters will handle 70A....

[Tonka]

Right, loads of reading later I'm wondering whether this problem is being caused by a wiring problem.

If I understand this correctly, the alternator is fed by a 12v supply to the rotor to power if up at lower revs, whilst at higher revs it self generates that power to a certain extent.

I need to check it's getting that power, does anyone know which wire I need to check?

Also, what does the "Charge" fuse on the o/s wing do? Should it be live all the time? Is that the power supply to the alternator? Cos if so it's not live tiill I raise the revs past 2000, and would point to my problem.

[NiftyNev]

Alternator should be putting out around 14.2V at the higher revs. Apart from that I gotta think about this more.

Just spent all day and half the night trying to fix a bloody Ford with ignition switch problems and still not sorted.

Nev.

[Tonka]

Thanks Nev, yeah it's a tricky one this.

[jim7564]

have you checked all the earths around the engine,possibly broken or something not earthing properly,multimeter to the alternator and batteries different points around engine bay,
see if anything different with things turned on.my alternator shorted out and had similar problems,
my car also a toyota has a faulty regulator which also causes problems but sometimes works better once lights etc are switched on.
when my alternator packed in i did not get any ignition lights but still had power to everything else.

[Tonka]

Hi Jim, yes I've checked all the earths, cleaned up connections and made sure that's all good. My alternator has a direct earth wire so it doesn't just rely on it's connection to the engine, not sure whether that's original or not.

[BillaBob]

Could be cheap parts used internally?

Hi there, The alternator has a permanent supply, and a switched ignition 12v supply. The permanent connection is the larger cable. You should have in the region of 14.2 - 14.8v from idle up. It should 100 percent be working & charging from idle. Don't beat yourself up hunting for issues that you may not have with your vehicle, & more than likely a fault with the alternator.
I have seen various issues with E Cheapo/Aftermarket ones, Ive seen the following with friends ones:
Not charging below 1500RPM -100 percent faulty
13v rising to 14 at 3000 rpm - 100 percent faulty
I rebuilt one for my self, using all new diode pack and regulator brushes etc, it would not charge until the vehicle had ran for about 10Mins!!! The strangest i have ever had!
Ive also seen one that the manufacturer had drenched in grey paint, and this got into the brushes and stuck a brush so the alternator just stopped working! Remember also, the alternator on these is a totally self contained unit, no external parts required for it to work.

[Tonka]

Thanks BillaBob, much appreciated. Well today is judgement day as I'm going to fit the new one and if that works ok we'll know it was definitely the alternator. I did get the old one tested by an auto electrician and he said it was definitely faulty, so it's gone back.
Interesting to hear you've had new ones as well and they've gone wrong, maybe it's not that rare then.

[Tonka]

Just thought I'd post to say that the replacement alternator is now in and it's all fine so far. So, that being the final test I can now say it was definitely down to the alternator I fitted 6 months ago going wrong. What a pain these things are to fit - this one was a total nightmare, took hours!

[jim7564]

good to here you have it sorted,alternators are a pain to fit but once you do away with the aircon its a whole lot easier