Looking to buy a 430 in jan.
Discussion
If it's a used TCU you will have the previous vehicles distance-per-gear logged. If it's a new TCU it will read zero when fitted. You can also erase the mileage easily with an SD3 unit, or manipulate the mileage by another method but it's fairly easy to tell if the units been tampered with which gives the game away. You can also look deeper into the instrument cluster coding and if you know what to look for it is obvious if somebody has altered it. Many cars I see have mileage discrepancies, it is unfortunately very common.
voicey said:
A PPI should include a scan of the TCU (assuming F1) - this will return the km traveled in each gear. Add them up, divide by 1.6 and the answer should match the odometer.
It is difficult to re-program these parameters in the TCU so they are a reliable check of mileage.
Precisely. Take these 'they're all clocked' claims with a very large pinch of salt.It is difficult to re-program these parameters in the TCU so they are a reliable check of mileage.
roygarth said:
Interesting. Could you be more precise?
Certainly. Mostly, any anomalies are thrown up during a PPI, but there are instances where alterations are discovered incidentally during the course of a repair. For example, sometimes jump-starting can cause a voltage spike in the instrument pack, resulting in regional settings to be lost. The ensuing repair operation requires resetting the unit with diagnostic equipment. Part of the procedure accesses imformation regarding mileage, and discrepancies between this algarythm and the displayed mileage can be seen. Altering the mileage in the gearbox TCU is just a case of altering the check-sum of one of the IC's within the unit.It is, of course, impossible to know when any such alteration has taken place. It could be that the vehicle is an ex-rental car coming off fleet while still fairly new, for example. Vehicles equipped with the "Florence architecture" electrical system (so 612 onward vehicles) are much harder to clock as mileage is stored within so many ecu's and "service vouchers" are stored within the NQS unit. Cars at the cheaper end of the market, with odd gaps in histories are usual suspects. It is a horrible practice, and an unfortunate legacy created by the self-propagating Mileage versus value stigma associated with cars that breach the magic 35,000 miles mark. I am not suggesting every, or most, have been altered but more have than you would realise. Of course there are also perfectly innocent explanations, sometimes instrument packs fail and have to be replaced, TCU's are often upgraded. Even fitting aftermarket wheels can in some instances alter the mileage added to the TCU.Edited by Cerberaherts on Wednesday 28th January 08:02
Edited by Cerberaherts on Wednesday 28th January 08:09
Cerberaherts said:
roygarth said:
Interesting. Could you be more precise?
Certainly. Mostly, any anomalies are thrown up during a PPI, but there are instances where alterations are discovered incidentally during the course of a repair. For example, sometimes jump-starting can cause a voltage spike in the instrument pack, resulting in regional settings to be lost. The ensuing repair operation requires resetting the unit with diagnostic equipment. Part of the procedure accesses imformation regarding mileage, and discrepancies between this algarythm and the displayed mileage can be seen. Altering the mileage in the gearbox TCU is just a case of altering the check-sum of one of the IC's within the unit.It is, of course, impossible to know when any such alteration has taken place. It could be that the vehicle is an ex-rental car coming off fleet while still fairly new, for example. Vehicles equipped with the "Florence architecture" electrical system (so 612 onward vehicles) are much harder to clock as mileage is stored within so many ecu's and "service vouchers" are stored within the NQS unit. Cars at the cheaper end of the market, with odd gaps in histories are usual suspects. It is a horrible practice, and an unfortunate legacy created by the self-propagating Mileage versus value stigma associated with cars that breach the magic 35,000 miles mark. I am not suggesting every, or most, have been altered but more have than you would realise. Of course there are also perfectly innocent explanations, sometimes instrument packs fail and have to be replaced, TCU's are often upgraded. Even fitting aftermarket wheels can in some instances alter the mileage added to the TCU.Edited by Cerberaherts on Wednesday 28th January 08:02
Edited by Cerberaherts on Wednesday 28th January 08:09
)Cerberaherts said:
I would only specifically check if directed to do so. I would estimate 25%.
Arguably people who ask you to check have an inkling something is not right? Factor in that you are not specifically asked to check all cars and we are none the wiser!My own view, FWIW, is that a very small percentage of cars being sold in the Main Dealer Network or by Marque Specialists have been clocked. At the end of the day if you get the ECU checked you can buy with relative peace of mind.
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