Obd2 scanner that does not jump odometer

[HULK 0]

Like the title says looking for a obd2 . & Please save the Scan Gauge 2 comments. Not interested in this product.  Is the Delphi DS150e VCI snooper like vcds for vw ? Or any scanner recommended that wont jump odometer. 

[o2bad455 2]

Not sure, but I think it's determined entirely by the pinout.  I've lost track of which scanners did what, and stopped caring after our 40K kms purchase jumped significantly after some scans plus real-time OBD port logging while I was trying to sort out an over-boost issue.  But for those of us who've unintentionally jumped our odometers by scanning through the OBD port, I've read that US MB dealers can read the true mileage from the ECU even after the instrument cluster's been corrupted.  Does anyone know if/how we can do that ourselves?  Here's what I'd read:

 

"There is some north american compliance issue with the ODBII port that can cause the odometer to arbitrarily roll forward when a cheapo ODBII scanner is used on the car. One such cheapo scanner is the one used for the Missouri emissions test. When I took the car in for a scan, it had 67,000 miles. When I left, it had 80,000 miles. There's not much I can do about this problem other than document it and warn you against using ODBII scanners. The correct mileage is stored on the car's computer as verified by a Mercedes dealer scan. It's just the display that's off."

 

Edited July 30, 2022 by o2bad455

[Willys 747]

I have an Autel that cost close to $300 and it works without jumping the odometer but unless you are wanting to sell it off, the car that is sooner than later why bother?  Just asking for a friend..lol. 

 

[MikeT 744]

The key is having a non-CANBUS plug, for whatever OBDII port device you use. A CANBUS type plug may jump the odometer, including the ScanGauge that you don't want.

 

Some suppliers such as Linear Logic will supply for free a non-CANBUS cable with the device, for use in the smart 450.

[LooseLugNuts 557]

ive used the delphi 150 with no problems

 

also used autel and foxwell scan tools on smarts with zero odo issues

 

 

im not familiar with vw vcds but i think its similar to delphi but the delphi is much less in depth (im basing that solely on the assumption that i seen the humble mechanic guy on youtube using what i suspect was vcds and it seemed to be very in depth ....similar to forscan)....if you buy a delphi expecting vcds or forscan type functions you will be dissapointed 

[o2bad455 2]

21 hours ago, MikeT said:

The key is having a non-CANBUS plug, for whatever OBDII port device you use. A CANBUS type plug may jump the odometer, including the ScanGauge that you don't want.

 

Ah, that makes sense, but I think there's a bit more to it. 

 

I can confirm that when I used my VCDS Hex-Com+CAN cable it definitely jumped our Smart 450 cdi odo.  So let's attribute that to CAN.

 

But I also tried two "dumb" VAG-COM cables (no longer remember which was which), one of which jumped it and one of which didn't (or at least I didn't notice if it did).  I believe I read that some of these dumb cables have pin 7 internally jumpered to pin 8 while others leave pin 8 open (something about being dual-K capable or not).  I think only the ones with pin 8 open are safe for Smart 450 cdi.

 

I also remember using a BMW cable with a physical switch on it (which had to be one way for a late 2004 BMW and  the other way for a late 2008 BMW) that definitely jumped the Smart odo in one switch position but didn't seem to jump it in the other switch position (no longer remember which switch position).  I just looked up that switchable BMW cable and saw that the switch seems to connect either pin 7 in one position or pin 8 in the other position, but not both.  So presumably it was jumping the odo only when pin 8 was connected to something, but not jumping the odo when pin 8 was disconnected/open.

 

In summary, CAN or not, I believe if pin 8 of the OBDII connector is connected to anything other than entirely open/disconnected, that there's a risk of it jumping the Smart odo.  That might not be the only reason, but it definitely seems to be a factor.

 

EDIT: Also, Smarty450's excellent KWP2000+ Guide (attached) indicates that some but not all KWP2000+ cables have pin 7 internally jumpered to pin 8, so pin 8 must be separated (e.g., clipped internally) for use on Smart.

KWP2000 Smart CDI Guide.pdf

Edited August 1, 2022 by o2bad455

[o2bad455 2]

Correction regarding the OBDII Connector:

 

CAN-bus uses pins 6 and 14 as standard, while pin 8 was used at manufacturer discretion (see below).

 

Some cars (at least some BMW) used pin 8 as a second K-line (in addition to pin 7), but Smart used pin 8 as a +12V switched source!

 

Some cables (e.g., some generic VAG-COM cables I've seen) used pin 8 as an extra carrier of the pin 7 K-line signal (possibly for redundancy, better signal propagation, noise immunity, or really anyone's guess why).

 

Here's the standardized OBDII connector pin-out:

 

Pin     Signal     Description
1           Manufacturer Discretion
2     J1850 Bus+     SAE J1850 PWM and VPW
3           Manufacturer Discretion
4     CGND     GND
5     SGND     GND
6     CAN High     CAN ISO 15765-4 and SAE J2284
7     ISO 9141-2 K-LINE     K-Line of ISO 9141-2 and ISO 14230-4
8          Manufacturer Discretion
9          Manufacturer Discretion
10     J1850 Bus-     SAE J1850 PWM only
11           Manufacturer Discretion
12           Manufacturer Discretion
13           Manufacturer Discretion
14     CAN Low     CAN ISO 15765-4 and SAE J2284
15     ISO 9141-2 L-LINE     K-Line of ISO 9141-2 and ISO 14230-4
16     +12V or +24V     Battery power

 

But here's the Smart 450 pin-out (per Evilution re 700cc petrol, hopefully also applicable to 800cc diesel):

 

Pin 1     SAM unit connection 9, pin 3. Diagnostics
Pin 2     No connection
Pin 3     ECU pin 102. TNA
Pin 4     Negative earth
Pin 5     Negative earth
Pin 6     No connection
Pin 7     ECU pin 110. K-line, Diagnostics
Pin 8     Switched live, fuse 20
Pin 9     ESP unit pin 11. Diagnostics
Pin 10     No connection
Pin 11     Steering assist unit, connection B, pin 2. Diagnostics
Pin 12     Restraint systems/Airbag controller pin 9. Diagnostics
Pin 13     No connection
Pin 14     No connection
Pin 15     No connection
Pin 16     Permanent live, fuse 11

 

It also seems to me that pin 1 might be causing an issue since many diagnostic cables use it to detect switched power but Smart has it connected to the SAM (where Smart's pin 8 is switched power).  It's possible that the odo jumping issue is actually happening at the SAM due to detection attempts on pin 1, and then being updated to the instrument cluster since those two (SAM and cluster) supposedly update each other to the greatest reading of either (while the ECU supposedly remains neutral while maintaining it's own private copy of odometer count), at least from what I've read so far.

 

Edited August 1, 2022 by o2bad455

[Willys 747]

The Speedo and SAM both store the mileages as to stop simpleton from turning back their odometers to get a better selling price from what I have read somewhere.   Most will go after the SAM's odometer reading and try and adjust it there not knowing the speedo is the safety check for such actions and it will set it or over ride the SAM adjustments.  All 3 computers in the Smart must correctly talk to each other to make up a successful running machine. They also must be taught to speak to each other to allow this to happen using the STAR diagnostic system.  I'm no computer geek of any description at all, I hate electronics but I have learned this much. I have no idea how to change the stored mileage to reset the lower number either. Never heard of anyone doing it yet either.
The next question is......you compare the Petrol version SAM to the diesel version SAM.....can you do that..?   Also, Transport Canada added their own magic box into the system when they landed here which ties into the SAM. I haven't seen anyone yet remove that from the system either.  So, perhaps that also has an effect on odometer readings being stored etc..?

Just spit balling as they say.....just things to consider...?

I have completely rebuilt my good Smart 450 CDI and would love to turn the clock back to zero to start all over again as a new car. Just for my enjoyment as I never plan of selling it. I do it to all my restorations.....as I never sell any of them so to speak, they usually were destroyed.....lol.   Jeeps. Bikes.   And the only one I have left is my 1952 Willys Pick-up.  It shows 10,000 miles since it's restoration over the past 20 years!

[o2bad455 2]

15 hours ago, Willys said:

The next question is......you compare the Petrol version SAM to the diesel version SAM.....can you do that..?   Also, Transport Canada added their own magic box into the system when they landed here which ties into the SAM. I haven't seen anyone yet remove that from the system either.  So, perhaps that also has an effect on odometer readings being stored etc..?

 

Good question and I have no answer.  But if similar odo corruption (cluster and SAM) was happening on both US gas 450 and Canadian diesel 450 due to the same OBD cable incompatibilities, and US dealers could read the ECU and correct the SAM and cluster based on the ECU's uncorrupted reading, then I don't see why it wouldn't also be possible on the Canadian cars even if the Canadian dealers are, shall we say, either less knowledgeable or less indulging.  In any case, I'll probably try to do a full backup (not just the map) of my ECU sometime soon, and seek help wherever I can find it to read the true odo reading from that (assuming it hasn't also been corrupted by the SAM and/or cluster).  I'll let you know if any success or definitive failure, either way.

[Mjolinor 91]

I have never heard of the mileage jumping before this in ten years of ownership.

 

It has to be a Canadian thing one would think. I think I have probably done most things to SAMs and ECUs including component level repair and remaps.

[o2bad455 2]

Perhaps it is a North American thing related to N.A. OBDII.  Since VCDS for VW was mentioned in the O.P., I'll admit I once used an official Rosstech VCDS VW/Audi interface (that I had to use one day for no other reason than that it was all I had on hand for generic OBDII testing/logging) that definitely jumped the Smart cluster odo, at least at first.  But I recall that Uwe (the head of RossTech) advised me to disable "boot in intelligent mode".  That change at least slowed the Smart odo jumping, but it was several years ago and I don't recall if it completely stopped it.  I haven't used that particular interface on a Smart again since then.

[MikeT 744]

1 hour ago, Mjolinor said:

I have never heard of the mileage jumping before this in ten years of ownership.

 

It has to be a Canadian thing one would think. I think I have probably done most things to SAMs and ECUs including component level repair and remaps.

Yes it is - apparently there are differences between the Canadian OBDII protocols and the European ones. Some people using ScanGauges and similar code reading and engine monitoring devices with their 450s - which were essentially lightly modified EU versions - had their odometers jump.

 

Linear Logic, who makes the ScanGauge, offered to every Canadian buyer of their unit a free non-CAN cable if they had a smart 450, which eliminated the possibility of this problem happening. Many have been using a CAN cable with their ScanGauge for years with no problem, which is a bit odd. I was one of them, with my first smart. I later put in the non-CAN cable.