2005 Polo 1.4 TDi Charging problem

[Corsadad]

Driving along the other day and the ABS (yellow advisory) warning light came on - strange as I wasn't braking or anything. I thougt I'd pull into the side to check things antway and as I pressed the brake pedal the red brake warning light began to flash accompanied by a loud audible warning.

I checked brake fluids etc and all appeared OK. Time to restart the car and see what the warning lights do only to discover the battery was flat and wouldn't turn the engine over. I started the car with a jump and all lights went out. I was quite certain at this point that the fault lay in the electrical system either:
1 - a battery plate had shorted itself out this would account for ABS warning. The unit will switch off and tell you it is off/faulty if too much or too little current about. Too little means it wouldn't work correctly and too much could fry the circuitry.
2 - Alternator faulty not producing enough charge. Covers the lack of charge in the battery (hence ABS cut out) but strange how no battery warning light. Subsequently checked by switching on ignition and saw that while about ten "warning lights" came on the battery/charge light didn't - amazing how you don't see that one doesn't come on.

Thankfully had access to battery condition meter which verified battery was perefect (although short on charge due to alternator fault). Using a multimeter I checked the voltage with engine running. Haynes suggests this should settle between 13 and 14 volts while charging. Mine settled at first at 11.5 volts then after "heavy" revving settled around 14.4 volts. Looking at this as way to low then a little high I took the alternator off (much simpler than Haynes suggests) and removed the voltage regulator/brush box.

Saturday afternoons see little choice of where to go for parts. Halfords parts man - our suppliers don't even list a complete alternator for your car sir let alone that bit.

Next stop local parts supplier - in luck friendly auto electrician happens to be there. Tells me the regulator is the only part that really ever goes wrong with these alternators replace should be no more problems - downside, you won't get from VW or factors only auto electrical establishment - won't get one till Monday morning, oh well. Monday came, simple job to fit and put all back together turn it on and under 12 volts under load - not good that won't charge my phone.

Luckily Auto spark was working round the corner and I was going to give in and pass it all on to him but he was extremely helpful. The lack of warning light now was the clue. Apparently if the warning light blows the alternator senses something isn't right and won't give out any charge - although sometimes revving hard will kick it into action (accounts for early variation in values). He has some cracking meters that after making a few connections confirms the theory. A simple test to check the bulb is to connect a wire from the blue wire on the rear of the alternator to earth turn the ignition on and the bulb should illuminate if not it has blown.

I now think I'm going to be stripping a dash apart. Wrong. You can't simply change the bulb as it forms part of the head unit and per VW you have to replace the whole thing. My head sank. The cheap fix, at least in the short term is to fit a warning light inside the engine compartment. He suggested I take a switched supply from the reversing light switch and earth through the blue wire at the alternator. This tells the alternator that it has a warning light and it will happpily give out a charge. I rig the test light up on a trial basis and sure enough 14.39 volts (close enough when the voltage regulator lists its fixed value as 14.4 volts).

Happy that this will at least allow a temporary fix that keeps the car mobile without spending hundreds of pounds. Thankfully I like to run cables carefully and tie them to existing looms out the way of moving components. As I tied the cabling along another loom I hit my luckiest moment. Beneath the starter motor I come accross a connector block with two wires going into one side and only one at the other. Strange - check inside the connector and the sheathing to discover that a wire has broken off the connector and inside the sheathing the cable has recoiled out of sight - colour - blue. A new piece of cable (even had some blue ) was used to remake this connection switched on ignition and hey presto the warning light comes on .

Thankfully I didn't spend £150 or thereabouts for a replacement alternator (only £30 for the unneeded regulator and brush box) and hadn't tried to strip down the dash (that would have been a fruitless exercise and expensive if I'd bought a new head). Overall cost me between 4 and 6 hours but in some ways (probably because it didn't cost as much as it might have done) I did have some fun, thrill of the chase etc especially when you get a good result.

A bit lengthy but may be of value to anyone who experiences simmilar problem(s)

[slicker55]

It has been a few years since you kindly took the trouble to document this story - very helpful to anyone following in your footsteps