Limp home mode or?

[YellowVMan]

Hello i'm new here.

Owned a 14 plate mk7 2.2 for 6 years now, it's been faultless until this morning. I know a little about machinal stuff but this has beaten me. About 4 weeks ago I noticed a red light flashing on and off but never caught to see which one it was but now I now its the battery or alternator light. It remains on all the time, yet the battery is being charged. I measured the battery tonight while the engine was at idle and it read 14.3 volts. The battery light went off then came back on but still the voltage never changed. I can't see no faults, no light dimming yet the engine power seems to drop slightly.

My mate suggested its in limp home mode but it can't be that because the van still does its usual speeds! he also suggested this forum so i,m giving it ago.

Chris.

[Mr Kludge]

Hi, I had an alternator fail on my mk7. It was an intermitent failure where it would sometimes charge and sometimes not. A voltage display that plugs in to the 12v cigarrette lighter socket might help to see what's happening. Also you could see if there are any fault codes stored with a code reader.

[YellowVMan]

Hi, I had an alternator fail on my mk7. It was an intermitent failure where it would sometimes charge and sometimes not. A voltage display that plugs in to the 12v cigarrette lighter socket might help to see what's happening. Also you could see if there are any fault codes stored with a code reader.

Thanks for that, did some testing this morning, voltage seems fine at 14.3 while the engine idles. no battery light displays until I rev the engine to around 3000 rpm, the warning light comes on yet the voltage doesn't change. Did some research and it looks to be either a fault with the van electrical system or the alternator has a fault. The alternator was changed a few weeks ago for a new refurbished one but the warning light was on before it was changed.

It's mental as nothing seems to be wrong while its charging. I got one more test to do tomorrow, using a voltage meter while driving to see if the voltage drops.

[longhair]

Your voltage will probably drop anyway which is normal when you start driving it, as the alternator will put out less charge as the battery gets topped up because of the smart charging system. Could it be a problem with the voltage sensor for the monitoring of the so called smart charging, which is connected to the negative post on your battery, maybe a bad connection in the wiring or the sensor itself.

[YellowVMan]

Your voltage will probably drop anyway which is normal when you start driving it, as the alternator will put out less charge as the battery gets topped up because of the smart charging system. Could it be a problem with the voltage sensor for the monitoring of the so called smart charging, which is connected to the negative post on your battery, maybe a bad connection in the wiring or the sensor itself.

Its not a smart alternator.

[longhair]

Oh right. I thought euro 5s came in 2011. I have a 14 plate custom with the same engine and mine has a smart alternator being a euro 5.

[YellowVMan]

Oh right. I thought euro 5s came in 2011. I have a 14 plate custom with the same engine and mine has a smart alternator being a euro 5.

I,m not sure as i,m the second owner, its a euro 5 2.2. funny this is charges the battery fine 13.8 yet that light remains on.

[longhair]

I was just thinking that maybe your problems are somehow coming from the smart charging circuit. If you disconnect the sensor on the negative terminal, on a euro 5, the smart alternator will revert back to being a regular alternator and put out a more constant charge, like yours seems to be doing. But will show a fault on the dash.

[YellowVMan]

I was just thinking that maybe your problems are somehow coming from the smart charging circuit. If you disconnect the sensor on the negative terminal, on a euro 5, the smart alternator will revert back to being a regular alternator and put out a more constant charge, like yours seems to be doing. But will show a fault on the dash.

No its not a smart charging system at all some engines had them and others didn't you can tel if it has smart charging by the small box on one battery terminal.

[longhair]

Oh well I don't have an idea what your issue could be then. Good luck getting it sorted.

[YellowVMan]

Oh well I don't have an idea what your issue could be then. Good luck getting it sorted.

Just found out the alternator cuts in and out. glad its going in tomorrow.

[longhair]

Oh well, at least you have found out what the problem is. Hopefully it won't be to expensive to sort out.