Amp meter not registering when turning ignition on

[redcarman]

Just got Griff, haven't got bible yet and have a problem. When I switch the ignition on and before starting the engine the amp meter doesn't register at all. Is there a fuse that may have blown or could it be an alternator problem?
Any ideas?

[Bluebottle]

Are you sure you mean amp meter? Griffs are fitted with volt meters as std.
If you do have an amp meter fitted, they are normally fitted to measure the ampage from the alternator so will read zero until the alternator is spinning.
If its your voltmeter reading zero then either your battery is flatter than Baldricks "Rat O van" or the connection to the guage or the guage itself is faulty
Edited to add - according to the bible, the instruments are on the same fuse as the heater.

Edited by Bluebottle on Thursday 24th May 20:24

[redcarman]

Thanks for the advice, the heater is working so it looks like it must be the alternator.

[GreenV8S]

redcarman said:

Thanks for the advice, the heater is working so it looks like it must be the alternator.

That's a wild leap of faith. You can't tell whether the alternator is working until the engine is running.

[Bluebottle]

redcarman said:

Thanks for the advice, the heater is working so it looks like it must be the alternator.

Amp meter measures to current deliverd by the alternator, the voltmeter measures power in the battery, not sure i follow your logic?

[redcarman]

Thanks for the tips, I was going by the fact that I had the same problem with my S3 and it turned out ot be the alternator.
I have been told to check the 100a fuse which is located on the right underside of the engine bay, but I can't seem to find it! Could it just be my age and failing eyesight or am I looking in the wrong place? Any hints on locating this elusive 100a fuse would be much appreciated.

[Bluebottle]

I was looking at the wiring diag in the bible and can't see the voltmeter on the circuit but I would have thought it would be connected directly to the battery supply via the fuse board (but I could be wrong), So no voltage reading would mean dead battery or broken connection to battery.
If the battery has life and you can start the car (If I am reading your post right it has and you can), I would use a multimeter directly connected to battery to confirm what voltage is there before starting engine and with engine idle above 1500rpm. If voltage increases then its being charged.
DavidBeer on here is the electrics guru tho, and would be able to give you much better insight and methods of diagnosing your problem than me.

[Bluebottle]

Oh nearly forgot, fuse location. Do you have a pre-cat or a 500?
If its a 500, then trace the big red wire back from the starter motor and you will find a plastic junction box strapped to the chassis rail near the starter. The fuse is inside that.
If you have a pre-cat then i am not sure and hopefully someone will be along shortly to help.

[spend]

Bluebottle said:

.. would have thought it would be connected directly to the battery supply via the fuse board (but I could be wrong), So no voltage reading would mean dead battery or broken connection to battery.

Its connected to the dash ignition feed - otherwise your battery would be flattened very often.

Dave

[spend]

Bluebottle said:

...trace the big red wire back from the starter motor and you will find a plastic junction box strapped to the chassis rail near the starter.

The starter would blow the fuse if that was the case! It is connected to the brown wires that go from the starter terminal pole (which is fed by the Big Red Wire) and then on to the alternator.

Dave

[Bluebottle]

spend said:

Bluebottle said:

...trace the big red wire back from the starter motor and you will find a plastic junction box strapped to the chassis rail near the starter.

The starter would blow the fuse if that was the case! It is connected to the brown wires that go from the starter terminal pole (which is fed by the Big Red Wire) and then on to the alternator.

Dave

Oops colour was a guess, Brown and red look the same to me

Thanks for stepping to help, electrics isn't my strongest point

[redcarman]

Thanks for the help gents. It's pouring with rain so haven't looked for it this morning, does this fuse effect anything else?

[redcarman]

At last rain has stopped so have been under the bonnet. Still can't find the fuse, the brown lead seems to go from the starter motor to the alternator with nothing between. Any other ideas? Oh and its a 500.

[spend]

Some early cars didnt have them, some later cars had them moved to the passenger footwell ~ some may have been modified....

Dave