2002 Polo 1.4 TDi alternator charging fault

[i-macca]

Hi,

I have got a problem with my girlfriends 2002 1.4TDi Polo. On Sunday I went to start the car, the engine turned over slowly, stopped and then sprung in to life albeit sounding as though the battery was going flat. We set off home and a couple of miles in to the journey the radio started blinking on and off, then the power steering, rear seat lock and brake lights on the instrument cluster lit up shortly before the power steering died. Thee were only less than a mile from home so I wrestled the steering and got back. Once turned off the engine wouldn't start and certain things such as electric windows and the radio wouldn't work. I checked the battery voltage and it was 2.5V.

Yesterday I jump started the car and checked the voltage and still it sat at 2.5V even when revving to over 3k rpm. Now the car will start and run without any spurious warning lights even though it only has 2.5V showing at the battery! We haven't driven it again just in case.

I found this thread - http://www.vwaudiforum.co.uk/forum/showthread.php?25274-2002-1-4-TDi-Polo-charging-system-fault-lights-on-dash-amp-power-steering-failure-!/page2 - and have taken the instrument cluster out and checked the continuity on the blue wire to the alternator. On our Polo it is pin 15 of the plug behind the cluster. The continuity is fine but I am not convinced that the alternator is at fault as according to the other thread it is energised by the cluster? I have checked and the battery light is not coming on at any point when the ignition is turned on or the engine is started. Does this sound like a cluster problem and is there anyway to tell for sure?

As an aside for a few weeks the oil low level light has been on even though the oil is fine (we have checked many times both before and after using the car). I'm not sure if this is related or whether the oil level sensor is also faulty.

Any help wouldbe very gratefully received!

Thanks,

Mark.

[kite]

I would take the battery off and charge it up.

follow me on twitter...kiteaudi...

[i-macca]

It's still not receiving a charge from the alternator though, there is something more wrong than just the battery being a bit flat.

[-M-]

You need a multimeter to check properly as a start. Measure across the battery(+) to give you a starting voltage - then change the MM negative lead to another good earth but after the earth lead from the battery. This helps to see if the earth strap/cable is at fault.

Then you need to measure the output from the back of the alternator(+) using a good earth but not the battery (-). The fact that you had 2.5V may suggest dead cells in the battery also - only when you charge and recheck will you know for sure.

[i-macca]

Across the battery terminals with a good multimeter was 2.5V. I also tried from a good earth near the back of the bay and got identical readings. Interestingly if I hold it on the terminals whilst the engine is running I can see the voltage dropping slowly by hundredths. Once the engine is stopped it creeps back up slowly.

I will check the output from the back of the alternator as you suggest and see what this brings back, thanks.

[Alan G H]

If the warning light on the dash is not working when you switch on the ignition, this normally indicates the alternator is faulty. The warning light usually earths through the brushes & if they are worn out, the light does not come on. I think your alternator needs rebuilding, or exchanging.

[i-macca]

I've now replaced the alternator with a new unit and the fault remains. There is no charge at the alternator output so it's not a fault in the wiring to the battery.

Can anybody offer any more help? I've just spent £160 I could well have done without spending and still can't drive the car. :(

[Alan G H]

I've now replaced the alternator with a new unit and the fault remains. There is no charge at the alternator output so it's not a fault in the wiring to the battery.

Can anybody offer any more help? I've just spent £160 I could well have done without spending and still can't drive the car. :(


Does the battery light on the dash come on now? And, have you got battery voltage at the main terminal on the alternator? And, is the battery fully charged?

[i-macca]

No, still no dash light when the ignition is turned on or once it's running. I've got battery voltage at the main terminal on the alternator. I've also checked all of the fusable links in the battery lid and they all have no resistance (same as between there and the alternator terminal). The battery is not fully charged but has enough grunt to start the car. I've never known a system that requires the battery to be fully charged to charge it though?

[Alan G H]

No, still no dash light when the ignition is turned on or once it's running. I've got battery voltage at the main terminal on the alternator. I've also checked all of the fusable links in the battery lid and they all have no resistance (same as between there and the alternator terminal). The battery is not fully charged but has enough grunt to start the car. I've never known a system that requires the battery to be fully charged to charge it though?

With the ignition switched on, is there any power to the small wire to the alternator? If not, you may have a problem with the dash connections or the bulb.

[i-macca]

There isn't, no. If I energise the alternator from the battery directly then I get 14.5V at the battery or alternator terminals.

I've had the cluster out and I know there is continuity on the blue wire from alternator to cluster plug and it's an LED not a bulb in the cluster. I'm a bit stuck here as it must be a cluster fault but I'm guessing I won't be ale to fix it myself. Has anybody had any luck with these cluster repair companies?

[-M-]

Have you looked at the earth strap from the battery to the body ? I have had previous problems due to this.

[i-macca]

Rock solid and perfect connection. The problem is in the dash, I'm 100% certain, I just need to know if there is anything I can do about it?

[i-macca]

I'll post the solution here in case anyone else has similar problems. I found the cause to be a broken wire in the end, broken off at the plug which is located on a bracket under the front of the car right next to the radiator drain tap. It had broken off in such a way that it still gave continuity but obviously couldn't carry enough current to energise the alternator. Worse still it had been repaired before and was covered in a swathe of yellow insulation tape!

I managed to take the plug apart and solder a new wire in to it keeping th factory weather seals then resoldered the new wire in further up and covered with heat shrink and amalgamating tape.

Plus an aside to this, due to taking out the instrument cluster a few times to check the connectors for continuity, the last time I put the cluster back in I found I had a loose connection somewhere as the power kept failing to it. I stripped the cluster down and found that the solders for the smaller of the two connectors had gone dry and lifted from the PCB. I reflowed these and now it's working fine.

Just a couple of strange things now; the airbag light is on and the drivers window will no longer auto up or down. The passenger side works fine though. I also noticed that although the passenger side electric mirror works fine, when adjusting the drivers mirror they both move. I have a friend with an Octavia and he reckons his car does this too and it's normal?

Any ideas?

[Cornwall]

Hi there, I dont know if you will receive this or not but you have just saved me hours of grief and i have the exact same problem. Legend for posting the answer.:beerchug:

[slicker55]

... thanks for posting - very useful to anyone trying to fix a similar issue