Alternator or Voltmeter???

[Knowler]

Firstly the good news and surprising it may be, but after a bit of a fluid change all round i took my new toy up to Leeds and back at the weekend and even though the traffic was heavy and stalling it performed marvelously but for one issue... The voltmeter played up, it sat at just below 13 until the heater, indicators or light were turned on at which point it dropped to between 12-13... I wasn't too concerned as i know how they can play up.. However on the way back it started quickly jumping between 11-13 and then after a while sat in traffic and then open road it dropped down to just above the red and stayed there regardless of whether i turned off the heater or lights... Its also hesitating a little on constant lowish revs....

Question: Should i trust the voltmeter and is my alternator on the way out or could there be another issue? Or could it just be my voltmeter is up to no good?

[Oldred_V8S]

Sounds like either a bad connection/poor earth or a faulty voltmeter. If the alternator was at fault I would suspect you would have got a flat battery by now, especially after running lights and heater fan etc.

[Knowler]

Oldred_V8S said:

Sounds like either a bad connection/poor earth or a faulty voltmeter. If the alternator was at fault I would suspect you would have got a flat battery by now, especially after running lights and heater fan etc.

Thanks so a bad connection at the alternator? or the voltmeter???

[TurboTony]

if you have a simple volt meter put it across the battery terminals and see the readings with the engine running and different items switched on. If you use the battery terminals and then the battery clamps you will see if there is a bad connection at the battery as well. It will tell you if the dashboard gauge is faulty. Hope this helps.

[Knowler]

Thanks Tony much appreciated.. i'll give that a go..... and let you know....

[Jed-S]

Surprised no one has mentioned the infamous yellow connector near the ignition switch. Mine showed low voltages and fluctuations when fan/lights were used until I bypassed the connector.

[Julesprivate]

I think we were starting "simple" (no offense to anyone!!) and a quick check of the voltages on the battery terminals is about as simple as it gets... and then move on to the more painful tests if needed...

[Griffinr]

When my S3 started randomly charging or not I found that the carbon brush on the back of the diode pack was sticking. Since cleaning and freeing up the volt meter shows steady charge but obviously varies depending on load.
Rob

[techbotics]

Julesprivate said:

I think we were starting "simple" (no offense to anyone!!) and a quick check of the voltages on the battery terminals is about as simple as it gets... and then move on to the more painful tests if needed...

do this... Mine shows 13v+ at idle the tvr guage shows 11v... Prob a bad earth to or a faulty guage.. I an slowly sorting the earth points..

Damian S3

[Knowler]

techbotics said:

do this... Mine shows 13v+ at idle the tvr gauge shows 11v... Prob a bad earth to or a faulty gauge.. I an slowly sorting the earth points..

Damian S3

Just trying to source a tester.. but quick question.. did your go up and down when your indicators were on?? When i set ou this morning it was fine, then after about 30 minutes it started to play up one of the signs was this....

R..

[Maffe]

TurboTony said:

if you have a simple volt meter put it across the battery terminals and see the readings with the engine running and different items switched on. If you use the battery terminals and then the battery clamps you will see if there is a bad connection at the battery as well. It will tell you if the dashboard gauge is faulty. Hope this helps.

+1

I always have a multi-meter in my s3, don´t trust english electrics

[phillpot]

Maffe said:

don´t trust english electrics

The problem with English (Lucas) electrics is that they often leak and once the smoke escapes they tend to stop working

[Maffe]

phillpot said:

The problem with English (Lucas) electrics is that they often leak and once the smoke escapes they tend to stop working

Yeah, always keep a ziplock back so you can catch the blue smoke
Problem is to get the blue smoke back into the system...