Help - Alternator Charge Light

[Michael2]

Hi guys, I'm looking at a friends 2007 4.0 V6 Petrol D3. She's a single mum and I helped her buy the Land Rover, so I feel somewhat responsible.

The alternator (battery) warning light on the dash is on.

The multimeter showed the alternator putting out 13.5V at the battery and the back of the alternator.

I recharged the battery with a smart cherger, that made no difference.

I swapped the battery with one from a TDV6 D3, that made no difference.

The TDV6 was putting out 13.8V as a comparison.

I've done a hard reset (switch car off - wait till hand brake warning light is off - disconnect +ve battery terminal and earth it) with no effect on the warning light.

I tested FUSE 20 under the bonnet (ALT) and it was fine.

I removed FUSE 20 and the alternator put out 14V, but the warning light stayed on. This settled to 13.9V

From this, I've deducted that it's not the battery.
And it's not the alternator (diode or similar).

Is there anything else to check, I would normally suspect the voltage regulator, but with so much electrickery in this thing, I don't know where to look.

If this requires a computer plug in diagnostic, I'm in Bayswater, and I can drive it to any nearby members who may have such equipment / expertise and time to offer such assistance.

Thanks in advance for your advice and assistance.

Michael

[Michael2]

Fixed.

I spoke with a member at MLR service who suggested the alternator (generator more correctly I'm told) was begining to fail, hence the warning light.

I removed it and had it bench tested by an auto elec, who found it was producing electricity, but could only pump out 60amps and was making a groan under load.

I replaced it and the warning light stayed on. Enquiries suggested the battery could have been damaged by the faulty generator.

I tried a hard reset and had the battery tested. The battery (2 yr old) had 980CCA (above spec) and no shorted plates. Internal resistance was lower than normal (good sign).

I opted to drive it to a workshop to have it fault read, but the warning light didnt come on again!! Apparently some cars need to be driven for a bit for the computer to realise that the fault is cleared, according to the battery guy.

So now all fixed for the price of an alternator, which is better than the price of a battery & alternator.