Hi,

The car is a 2005 Skoda Fabia Mk1, 1.4 TDI, 75 hp.

I found this 2-pin connector/component underneath my car while it was on a lift, but I don't know what it is.

It appears to have a 2-pin electrical connector, but currently:

• One pin has a wire connected to it.

• The second pin is completely empty/broken.

• There is also a separate loose wire, marked with the green circle in image, which is not connected to anything.

I'm wondering if this loose wire is supposed to connect to the empty second pin of the blue-marked component.

Does anyone know exactly what this component is and what the two wires/pins are for?

Thanks!

They go to the alternator.

The blue wire is the excitation, which helps the alternator boot-up when engine is first started, the other is a signal wire from the alternator to the engine ECU, telling the latter how hard the alternator is working to satisfy electrical demands on a continuous basis.

If the blue wire breaks, the battery light doesn't illuminate when ignition is switched on, and you would not get any warning if the alternator output fails.

If the other one fails, some Fabia variants will display the ASR warning light after 10 minutes of driving. Cars that lack traction control/anti-slip regulation do not show any warning lights but a fault code will be present in the engine ECU if interrogated.

It's odd that the blue wire doesn't appear to connect to a blue wire at the black two-wire connector. How does your battery light behave?

Here's the section of circuit diagram covering this connector pair.

T2w is the connector pair in your blue ring. It should have a brown/red wire coming from the alternator connector (T2v/2 labelled DFM above) which changes to lilac/green at T2w/2 as it continues on towards the engine ECU. [27] indicates a continuation on another page of the diagrams.

The excitation (D+) wire is blue all the way form alternator connector to the T18a/9 connection which is in the cabin, at a control unit that would be called the BCM in modern parlance.

Repair both, ideally using pre-wired 'proper' waerproof connectors

(part numbers are on each half, in tiny writing), or just bypass the connector pair.

4 hours ago, Breezy_Pete said:

They go to the alternator.

The blue wire is the excitation, which helps the alternator boot-up when engine is first started, the other is a signal wire from the alternator to the engine ECU, telling the latter how hard the alternator is working to satisfy electrical demands on a continuous basis.

If the blue wire breaks, the battery light doesn't illuminate when ignition is switched on, and you would not get any warning if the alternator output fails.

If the other one fails, some Fabia variants will display the ASR warning light after 10 minutes of driving. Cars that lack traction control/anti-slip regulation do not show any warning lights but a fault code will be present in the engine ECU if interrogated.

It's odd that the blue wire doesn't appear to connect to a blue wire at the black two-wire connector. How does your battery light behave?

@Breezy_Pete Thanks, that helps.

The battery warning light works normally - it comes on with the ignition and goes out after the engine starts.

When you say "it's odd that the blue wire doesn't appear to connect to another blue wire at the black 2-pin connector", I guess someone previously repaired/replaced part of the wiring and used a different coloured wire? Also, since my battery warning light works normally, maybe blue D+ wire is actually working correctly? If so, should I just leave it alone and only repair the disconnected lilac/green wire?

And if that lilac/green DFM wire has been disconnected like this for a while, what problems or symptoms could it actually cause, especially on a car without ASR? I don't think my car has ASR/traction control, and I have no fault codes via OBD.