ABS warning light/Brake warning light /No Speedo/EML/fuel gauge not working, 2006 1.9tdi Auto

[Manxgp]

Hello to all, so driving along and the speedo starts flicking up and down soon to be joined by the fuel gauge doing the same thing. At some point the speedo stopped working totally but the fuel gauge has started working again. To add to the issues the EML has come on all the time, ABS light now on and brake warning light that beeps when I apply the footbrake. The car still drives fine but with occasional emissions warning coming up on the dash for a second and then off it goes.

So my question is what is going on ? I have a spare ABS ECU that I could swap onto the car from a similar age VW , not sure about any coding issues, I, can send the ECU and the ABS ECU off to be tested. To add to my problems when the garage plugs the professional Diagnostic tool into the car it now wont let the tool interact with it, the thinking is its got no live feed coming from the car to the tool?

as always any help/advice a steer in the right direction is much appreciated, cheers

 

[mty12345]

Obvs it's very hard to say without the car in front of me, but with all that going on, i very much doubt it's the ABS ECU, would be too much of a coincidence. Sounds more like some sort of electrical fault with the car as a whole. Do you know if they can't communicate with any control unit, or just the ABS one?

First thing i would do is check all the Ground/Earth points on the car. Start with the negative/ground cable to the battery, check it's tightly connected and free of corrosion. Check both ends of it, both at the battery and where it is bolted to the car.

If that is good then I would suspect the main earth cable that goes from the engine block to the negative of the battery. I'm unfamiliar with where that is on your model, but on the similar age leon they are underneath the tray that holds the battery. It will most likely be near where the battery negative cable bolts to the body of the car. The garage should be able to locate it if you cant't, it's either a braided metal strap or a fairly thick cable. The reason i suspect that, is that ground is usually shared between most of the underbonnet componants, including the ABS unit and speedo etc. If you have a loose/broken/corroded connector, that could generate all those faults. Again check both ends of it, the bit bolted to the engine and the bit bolted to the body.

Edit: If you have a multimeter you could measure the resistance in ohms mode between a metal part of the engine block (make sure it's free of grease/dirt/rust so you have a good connection) and the negative terminal on the battery. If you have a good earth then the reading should be no more than a few ohms. If it's a lot higher then that would confirm a bad ground from the engine block.

Hope that gives you something to go on. Keep in mind that some garages are useless with electrical issues, and you may be better off going to an auto-electrician.