Naughty CANbus odometer "interface". (Fakes mileage.) - Page 1
Forum section: electronics / general

author: johnlsenchak
author_rank: Frequent Contributor
timestamp: December 09, 2019, 10:27:04 pm
content: Naughty CANbus odometer "interface". (Fakes mileage.)•Dec 9, 2019bigclivedotcomI was sent this device by a mechanic who found it behind the instrument panel of a car. When removed another 40,000km appeared on the clock. The unit appears to "massage" the data between the ECU and the display.Posted 12/09/2019

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: December 09, 2019, 10:51:39 pm
content: Seems this isn't the only design on the market, either.https://www.aliexpress.com/wholesale?SearchText="can+filter"This type of device presumably has some legitimate uses, such as calibrating the speedometer. However, all the aftermarketinstallation guidesseem to only indicate how to set it up to match the model of the car, meaning the default behaviour will be used. And there are limited pins for solder bridging in any case, precluding complex configuration. Given the default behaviour is probably some combination of mileage subtraction and division, it would be hard to justify this as anything other than a nefarious device ...

author: blacksheeplogic
author_rank: Frequent Contributor
timestamp: December 09, 2019, 11:42:15 pm
content: Quote from: I wanted a rude username on December 09, 2019, 10:51:39 pmI've seen them used 'legitimately' on Bikes where there's no easy/cheap method to deal with MPH verse KPH and the person who imported the bike wanted the cluster to 'read' correctly even thou the units were not correct i.e. cluster indicates a speed of 60.

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: December 10, 2019, 02:16:51 am
content: That's reasonable. Or even just making the odometer tick at the correct rate, instead of 3-9% faster as they tend to. But for these specific modules at least, there's no fine-grained control to allow that.

author: AndyC_772
author_rank: Super Contributor
timestamp: December 10, 2019, 10:52:14 am
content: No inspector would, or would be permitted to, dismantle the dashboard of a prospective purchase to search for modifications.

author: Rerouter
author_rank: Super Contributor
timestamp: December 10, 2019, 11:53:38 am
content: They are very common devices in europe. Generally mercedes and bmw where they add so many different ECU's with a copy of the odometer. On ignition they all agree on the highest stored value (if checksums don't fail)People set them back usually before the required inspection to reduce how much they have to pay for something (some milage threshold)But because there are so many ECU's (engine. Transmission, abs module, battery controller, window controller, service blackbox, etc, 13 is a usual number). And people are lazy. These modules exist. So you only need to pull the cluster from the car. Program it on the bench via a test harness (usually via canbus without needing to open it) fit the module to break the canbus lines.It intercepts the vehicle ecu's pairing the milage. Listens to a few modules that send the request first. And reply back with that milage. While forwarding to the cluster that all other modules are about 100km so it never pairs higherVehicles with these modules will generally show a difference between the obd canbus and the dash. There are some modules that can also hijack the obd socket and lie to the dealer tools. But it is rare as they are expensive and needs to be updated every 6 months or so.There are tools that can set all of the ECU's in one go. But with an entry price of about 5-8K USD most people are more willing to play with these.Never used them myself. But know the industry.

author: SparkyFX
author_rank: Frequent Contributor
timestamp: December 10, 2019, 01:36:44 pm
content: Odometer manipulation became a crime here in 2005, because it usually is fraudulent. Selling a vehicle with a manipulated odometer (or misrepresenting the item, give or take some tolerance) was just as fraudulent before that date, but since then such services are pretty much considered illegal, even when the owner pays for them to have his property altered.The interesting part is that speed and odometer are usually two signals on the bus and that device manipulates just one. Then there is the risk of the connector falling off while driving and introducing new errors that were not anticipated.From a legal point of view selling a car with such a device is a bad idea in the first place, as it contains the evidence for the manipulation and a lawsuit has a high chance of success... and there would be no real point in misrepresenting the item if it was not in the condition where the mileage would be credible. So either you have to suspect something or notice something and then find the evidence or there would be no high financial gain. Market prices are what they are in the long run, manipulations usually only work for a short time or in a few cases.Quote from: Rerouter on December 10, 2019, 11:53:38 amIt also means that the documentation of maintenance at the dealership for this car will not show the actual mileage, therefore when selling the vehicle with a manipulated odometer it will not be obvious by checking those documents. Outright fraudulent behavior.

author: SeanB
author_rank: Super Contributor
timestamp: December 10, 2019, 06:39:07 pm
content: So common that here in the car trade it is called " getting a hair cut", where a vehicle will be transferred between 3 provinces in a short period, so as to ensure that the original owner registration details is dropped off the registration form, at least making finding it harder, so that the less than upright dealers can then sell the car at a lower odometer reading. Commonly caught out with vehicles with a service history at major franchise dealerships, as there you can go in with the vehicle, and they can, via VIN and engine number, pull up the full service history, which includes all work done, time, cost and vehicle particulars on entry, including the odometer reading, and often the results of diagnostic scans done on it. Most commonly up to 100 000km is trimmed off the vehicle.Then, I did buy a vehicle with 93000km on the odometer, and drove it for a very long time, and sold it with 16000km on the odometer. It was a 5 digit odometer, and I rolled it over twice.