Breezy_Pete

One thing that may be worth considering is upgrading/upsizing the cable between alternator and battery fusebox; that would minimise any resistive losses in that leg. Not sure if the cars that had 120A alts from new had a bigger cable but I think the standard ones are only 16mm². For the same reason I would suggest removing, cleaning and refitting the main earth cable between engine and chassis. Both ends of this are quite exposed, and the engine end gets thermally cycled too every time the car is used. Good clean connections on this cable can give you much improved battery charging and general performance of the electrics. Goes to the inside face of the nearside chassis leg and to one of the starter motor fixing bolts at the other end. Photo shows the chassis leg end, and the repaired starter solenoid wire just above it.

Do you know if your car has washer fluid level sensing, and oil level sensing installed? I'm wondering if the instrument cluster coding may have been corrupted, and it's now giving warnings because those systems aren't present?

Look at (and photograph) the wiring to the motor module while you're looking for the motor part number. The older set-up has an orange/brown + orange/green twisted pair of CAN wires going to pins 4 and 6 of the 8-way connector. The 10/04 onwards version lacks these wires and uses those pins for other things, according to the circuits. I'm a little confused by (pirated) ETKA listings that suggest the motors changed part numbers in July 2004 rather than Sept/Oct, from the 6Q... to the 6Y... parts. I would have thought the dates would match up? Actually, having said all that, I think if you have the wrong era motor module, the connectors may just not fit?

Having unplugged the connector, and unbolted the check-strap, it's probably remarkably easy to take the whole door off for massively improved access. Certainly the case on a mk1. Just anticipate the weight as you lift it off, have some foam or something to stand it on and lean it against, and get an assistant to help refit it without knocking anything.

Exactly that. No problem will result. I think it only comes into play when the demand is at or near 100%. At that point some 'luxury' current consumers like heated seats or auxiliary PTC electric cabin heaters might be inhibited until the rpm rises (which naturally increases alternator capability) or other demands decrease (e.g. heated rear screen).

I like your thinking, and am glad to hear the other fault seems to have been cured.

These screws can be a pain, especially if you dive in there without suitable preparation. This is what they looked like when new: They're generally a Torx T25 tool fitment, and they're mostly a bit or a lot rusty, and almost always have grit and mud in the head recess. If you do nothing about the latter before attempting to undo them, the tool tends to slip, or you can rip up the head and make life more difficult than it ought to be. I tend to replace any that are badly corroded and like using this fella on ebay for such things. But before you can replace, you need to get them out. Things like an old toothbrush or a small wire brush can help, but both will struggle to get deep into the head recess where the grit and dirt are really in the way of the tool getting good purchase. So use a little pick tool instead. I tried this for the first time a week or two back and it works beautifully, getting right to the bottom of the recess, and into all the corners nicely. Anything similarly pointy should do, but these sets are available very cheaply on ebay/Amazon/anywhere. Suddenly the torx bit goes in about 2mm further and just releases the screw easily. Bloody obvious strategy in hindsight, but may be handy for anyone who has successfully evaded the bloody obvious to date.

Has the other cluster problem stayed away?

Yep, just as you say.

@Ferrit's solution seems like an economical fix if it's still holding out? I've put up a Wanted advertisement on here for non-working motor modules, hoping to spot something if I have a few to look at and try to run. Nothing visually on the first one I've examined minutely, though I've only looked at the circuit board so far, not even tested the motor alone.

Hmm, seems very young mileage-wise to have worn out anything in the alternator. Can you double-check whether you see voltage on the L terminal (pin 1, rounded side) of the alternator loom connector when ignition is switched on? Things may have changed by 2011, but I'd expect to see that on earlier cars.

How many miles has the car done?

Yes, that wire will prevent the driver's side module from working, and that module is what looks at the switches on the driver's side and tells the passenger side module to open/close its window accordingly. Repair that wire, looking also for any others that may need pre-emptive action to prevent breakage in the near future; cracked insulation may be a sign of near failure.

Goes straight to pin 1 of the 8-way connector on the back of the instrument cluster. Might well be the solder joint of the male connector to the board rather than the wire itself. A simple fix might be to find someone with VCDS to re-code the instrument cluster to ignore that wire. Two minute job. Otherwise I would extract the cluster and remove the circuit board from the plastic housing, then reflow that joint. Can probably get enough access without removing the needles and bezel.

I doubt there's any need for further testing. It's such a common failure I think it's almost certainly the busted wires. See if you can get a photo through that slot in the undertray, if yours has one there like on Polo? If you frigged it with a permanent live it would flatten your battery when the car wasn't running, and if it were ignition switched it would also need a diode in series. Easier to maybe get a friend or professional in to mend the existing wiring.

Scroll down to about halfway down the page here: load signal alternator cable - Skoda Fabia Mk I - BRISKODA The working pictures are of my Polo, but I think your Fabia will be very similar. There's a possibility that the connectors will not be in the same order on that bracket, but just look for the black 2-way connector pair with a blue wire broken. Both wires may well be broken. Mend that/those wires and all should be well again.

Just out with the dog, will link you to a thread with pictures when I get home.

Does the battery light come on with ignition? A very common fault involves wires breaking at a plug/socket connection in front of the gearbox. If the blue wire breaks, the battery light no longer comes on at ignition on.

They're not + and -, they are L and DFM, if you're talking about the thin wires into the two-way connector. No fuses involved. L is the exciter wire which should show 12V or a little less with ignition on. DFM is a feedback signal to the engine ECU telling it what percentage of available output is being used. Depending on the ECU, this will probably sit at 12V or 5V when not connected to the alt. What problem are you working on? Does the battery light come on at ignition on?

Nearest to rounded side. Labelled L on alt.

If the radio is factory original fitment it won't need any code putting in subsequent to a battery disconnection. My understanding of the wiring to your engine ECU is that there aren't any permanent 12V connections, so disconnecting the battery is no different to switching off the ignition though. By all means try it, but I wouldn't expect any sort of reset to occur. I reckon there's another problem somewhere.

Here you go @Lord_Moppy. My set-up for talking to the J519 module off the car. Hacked-about KKL cable with K-line (blue wire), 0V and 12V (red) connections broken out. Main permanent 12V (red) and earth (black) connections: 18-way brown connector Ignition 12V (pin 12) K-line (pin 1) Permanent 12V (pin 5) Earth (pin 8) And everything on The pin 5 and pin 8 connections on the 18-way aren't essential for VCDS to talk to the module, but having them hooked up removes some errors to do with battery voltage. To connect other modules in, power the individual module with whatever supplies it requires, and hook up the relevant CAN connections to either XS2 (convenience CAN bus) and/or XS6 (drive CAN). Haven't tried that yet.

The UV torches are very cheap. Just looked on Amazon, and currently there are some at <£3.50. It may be the case that this will work even without dye in the system, if there's something in the PAG oil that fluoresces. I might test that theory today, as I have a small pot of oil. Edit: tested just now and that's a negative. If the system has near zero pressure it's the perfect time to fix any leaks that might be found this way. A 168g container that magically turns into 453g of gas sounds fraudulently dodgy.

Detection is feasible via a combination of Central Electrics (09) coding and indicator lighting circuit impedance decrease. On my Polos, a simple/single increment of the coding tells it to 'expect trailer addition sometimes'; then the decrease in impedance caused by the parallel trailer-board indicator bulb compared to its absence tells the electronics (in module 09) driving the indicators that there are more bulbs in circuit. All the indicators are driven by a chip that has load current monitoring. The detection is only used for the trailer indicator telltale in those cars, to the best of my knowledge; but could be used for other things I guess, once the addition is 'spotted' by the system. I knew for sure it was the impedance difference that was involved when I tried the LED lighting board for my boat trailer, and it failed to correctly illuminate the trailer indicator telltale on the dash. Some resistors to ground across those two LEDs to mimic 'real' bulbs in that lighting board solved this problem.

So there's probably a way to open that trunking. Get in there and start pulling and poking.