Touran Rear Right Abs Wiring Problem - have VCDS codes - Wire colours?

**TdiBlacky140** · 13-07-2020,08:16 PM

Sometimes I wonder if VCDS is any good for solving diagnostic type issues.

For instance, even with VCDS codes you still can't be 100% whether an abs sensor or the abs ring is at fault, no code confirms completely and it can still be 50 / 50 which of the 2 parts is faulty, you could guess 50 / 50 without VCDS.

Also, good branded abs sensor and hub ring replaced and hopefully safe to assume operating correctly, can you 100% condemn the wiring or the Ecu with the 2 codes Incorrect Signal
+ Supply Voltage Terminal 30 - lower limit exceeded - intermittent or are you still left with a 50 / 50 choice of either option.

Also, with sensor disconnected there's 4 codes including "Mechanical Failure", how can it be mechanical if a new hub ring was installed. How can it be "Mechanical" if "Mechanical" fault wasn't there before and the only change made was disconnecting the sensor? How can disconnecting the sensor produce a "Mechanical" fault, surely it should produce an electrical fault. So basically, VCDS lists every possible cause for the problem and you're still left guessing as to which component including wiring is faulty. Unless the term "Mechanical" in VCDS doesn't actually mean physical mechanical?

Sure I can guess and test all these 4 parts (sensor / hub ring / wiring / Ecu) without VCDS to an extent.

**Crasher** · 13-07-2020,08:59 PM

Now you have hit on an interesting subject, the value of fault codes. It is not fair singling out VCDS in this respect, it is common to all fault code reading systems... you CANNOT depend on fault codes, they are only a first step to quick diagnostics. The next step is to use the measuring block and self test systems provided by the cars manufacturer (not by VCDS) which the diagnostic system uses, it is only as good as the data the car provides so it takes skill and experience. Blaming VCDS for one’s inability to solve a problem is like criticising a 13mm spanner for being useless if it does not tell you which way to rotate it.

**TdiBlacky140** · 13-07-2020,10:09 PM

Originally Posted by Crasher

Now you have hit on an interesting subject, the value of fault codes. It is not fair singling out VCDS in this respect, it is common to all fault code reading systems... you CANNOT depend on fault codes, they are only a first step to quick diagnostics. The next step is to use the measuring block and self test systems provided by the cars manufacturer (not by VCDS) which the diagnostic system uses, it is only as good as the data the car provides so it takes skill and experience. Blaming VCDS for one’s inability to solve a problem is like criticising a 13mm spanner for being useless if it does not tell you which way to rotate it.

Don't get me wrong, I'm not singling out VCDS, it's just the one I'm using, but i should have said any diagnostic scanner in this example.

I understand and appreciate a fault code doesn't pinpoint the exact fault, but is only a guide.
However, in this case, so far all the diagnostic has being good for is pinpointing which of the 4 wheels is at fault, which is good as it saves you pulling 4 wheel / hubs off to check all sensors and abs rings for damage etc. So, the live data aspect of a scanner is good in this respect to pinpoint which wheel isn't displaying a speed.

However, the faults codes are pretty much useless so far.
If I got the Ecu connector disconnected and found continuity to be broken via my multimeter, and thus determined the issue to be a broken wire which is then a case of repairing or replacing the wire.

Assuming the above scenario of a broken wire is the "actual" case and was determined in the above method, what help did the diagnostic scanner regardless of brand actually give?
If the Ecu connector wasn't so inaccessible, I could actually test all the abs sensor wires for continuity via my multimeter and narrow pinpoint the wheel and wire that way, which would have made the live data from the scanner non-essential as well.

I haven't given up on this issue, I'm confident I can solve it once I get access to the Ecu connector terminals, it's just awkward when its not your own car and can't get access to work on it very often or for any decent length of time. The point I'm making is until I get access to the Ecu connector plug, it would be good if I could use the fault codes I retrieved from the diagnostic scanner to try pin-point the issue in the meantime, however as they indicate every possible component / scenario they just seem to me to be of very minimal use.

Unless, I'm missing something, and over-looking them, perhaps they are in fact helping to indicate the problem and I'm over-looking their clues. Perhaps the code "Supply Voltage Terminal 30 lower limit exceeded" is telling me the wire is damaged, hence the supply voltage being lower than it should be. Hmmm, but why does it list all other options too, surely a diagnostics scanner of any brand should be helping to narrow down possible faults, it's not doing that by covering itself by listing every option.

I can fix this issue without a diagnostics tool, if anything, the diagnostics tool is just confusing things in this instance. I'm not saying it's useless in every case.
What is it with VW's and abs / traction control warning light issues anyway, their cars in general seem to plauged with such issues from abs pumps to steering racks, to steering column sensors, etc...

**TdiBlacky140** · 19-07-2020,08:02 PM

It seems the new sensor was faulty, it was of the Pagid brand, would of expected them to be fairly decent considering they were oem for some german cars and possibly still are for Fiat / Alfa if I'm correct? Anyone here have any bad experience of this rand recently?