OBD2 and ELM327 problems with Xsara

[xsaras4ever]

Hello ,

has anyone bought this to work with a Xsara ? It wont communicate with our Xsara 2, 2.0 Hdi .

http://www.ebay.co.uk/itm/V1-5-ELM327-E ... TQ:GB:1123

Thanks

[Stewart(oily)]

I bought the very same thing a couple of years ago, thus far it has failed to connect with a Freelander and two Xantias, though the USB connection works a treat
Looking for a Lexia interface now, and sticking with the Xantia too for that matter.

[xsaras4ever]

Its the air-bag light that is lit on the dashboard.

Have disconnected the battery, have cut the blocks under the seats and re-soldered, still no improvement.

Unfortunately we have already bought that cable and software, and have a ton of other software too - about 20 applications.

Nothing connects.

[Mandrake]

A diesel Xsara won't be EOBD compatible as it wasn't mandatory in the EU for diesels until 2004.

A Lexia is the only thing that will talk to it.

PS Stewart, Xantia's are definitely not EOBD compatible either, a Lexia is the only thing that will work!

[Chlorate]

That looks rather interesting actually...
I'm interested in expanding the usefulness of my Lexia laptop, has anyone had any luck on lesser cars with that?

But as with the above, Citroen was a bit awkward with OBD-II compliance. Since they weren't attempting to sell anything in the US they held on until the EOBD regulations were enforced later (2000 for petrols 2004 for diesels).

[xsaras4ever]

Hello again ,

I'm a novice at this, so if I have got this wrong then sorry.

However, this webpage

http://pinoutsguide.com/CarElectronics/ ... nout.shtml

suggests that our Xsara Phase 2 Hdi can be ODB2 compatible.

We bought the previously mentioned kit just to get the ELM327 cable and one of the applications we have on our PC is Multi-Diag, which looks the business.

Would love to get our PC talking to our car, even if we have to get stuck in with the soldering iron.

We also have a 2004 Megane diesel, it wont talk to that either, even though it is on the list.

Any help would be welcome.

Thanks

[Chlorate]

That list also suggests that the Xantia HDi is OBD-II compliant, and we know they aren't.
The socket in the car is an OBD-II socket (and the pinouts according to that website are as standard) but I have a feeling that the data coming out of it is in a propitiatory format - hence why the PSA interface unit is required.

[Mandrake]

Indeed.

An OBD-II socket has standardised pinouts, however there are 5 different physical signalling protocols (voltages, data rates, handshaking method etc) of which a given model of car typically only implements one. So first an interface has to support the signalling method at the physical level.

http://en.wikipedia.org/wiki/On-board_d ... _connector" onclick="window.open(this.href);return false;

Older Citroens (Xantia, Xsara etc) do implement one of the standard OBD-II physical level signalling protocols, however its not enough for the physical over the wire protocol to be compatible - its only a means to send data between the diagnostic tool and an ECU, you still need to know WHAT data to send and how to interpret what data you get back.

An analogy is the RS232 serial interface - it defines the physical pinouts, voltage levels, and framing of bits/bytes, parity, flow control etc that allow two devices to send bytes of data to each other, however what data you send and what that data means is up to you... A two way radio only lets two people to talk to each other if they speak the same language!

OBD-II as well as defining the physical signalling protocols also standardises the format and meaning of the data itself, fault codes and data PIDs are defined, as is the way of querying and retrieving them, bidirectional control commands are defined, and so on.

Old Citroens that are not OBD-II compliant do NOT follow the OBD-II standards for the actual meaning of the data, thus can't be queried by a standard OBD-II diagnostic tool. They use their own proprietary model specific "language" when communicating, which isn't publicly documented. A few high end (read: very expensive) multi marque scanner tools like the Snap On Verus Pro may be able to communicate with them but only if they've licensed the protocol from PSA and added specific support for it in addition to OBD-II compliant models.

All the list on that website says is what physical signalling protocol those models of Citroen use but that doesn't mean they're OBD-II compliant at a data query level, nor does it mean they'll work with generic OBD-II software with a generic OBD-II reader.

In theory someone could write some custom software for a generic OBD-II interface that knew how to talk to the ECU's in older Citroens, but it would take either inside information (likely only licensed to the likes of Snap on) or a lot of reverse engineering that just wouldn't be worth the effort. I'm not saying there isn't such software out there somewhere but its likely to be very limited in utility compared to a Lexia.

If there was a cheaper alternative to a Lexia for non OBD-II compliant Citroens I'm sure someone would have found it by now! Also remember even on OBD-II compliant models a Lexia can still do a lot more than a generic tool, for example updating ECU firmware.

[Mandrake]

suggests that our Xsara Phase 2 Hdi can be ODB2 compatible.

We bought the previously mentioned kit just to get the ELM327 cable and one of the applications we have on our PC is Multi-Diag, which looks the business.

Didn't see this when I posted my previous reply. Multi-Diag should work with an older Citroen, it's made by the same company (ACTIA systems) who make the Lexia, and I know it works with the ES9J4 in a Xantia V6 which is definitely not an OBD-II compliant ECU.

However, as far as I'm aware Multi-Diag will not work with a generic ELM327 interface It uses a proprietary ACTIA interface very similar to the Lexia 3 interface used with Diagbox.

In fact I've read that it's possible to "re-flash" the firmware on a Lexia 3 to make it compatible with Multi-Diag, however if you had a Lexia you could just run the Lexia software and wouldn't need Multi-Diag in the first place, so not much help in your situation...

[xsaras4ever]

Thanks Mandrake for your excellent replies.

2 further questions.

1.) If we have Multi-diag is there a cable and driver software we could buy to get it to talk to our Xsara ?
2.) As our Megane diesel is 2004 (though possibly therefore manufactured in 2003) do you know if it is OBD2 compatible ?

Thank You

[BX]

If the xsara has a bosch injection system then it is likely that it will communicate with an eobd (the system used in europe) or with an obd2 (USA) interface even though the vehicle isn't eobd compatible. I have got an ELM 27 to talk to a 01 Synergie 2.0L HDI. I know for definate that the Siemens injection system won't respond. Most of these EOBD/OBD2 systems will only read codes from the engine. Indeed even if the vehicle is EOBD compliant many engine fault codes are not presented to an EOBD diagnostic tool by the vehicle. These codes can only be read by the vehicle specific diagnostic tool. The rule of thumb is that only faults affecting emmissions can be read. For instance a fauly fuel rail pressure sensor on an EOBD compliant Transit will generate a fault code that can be read by a standard EOBD diagnostic tool but a faulty crankshaft position sensor will not. The reason being that the faulty crankshaft sensor causes the engine to stop and thus has no effect on emmissions. Normally EOBD diagnostic scanners cannot read airbags, ABS or body computers. I haven't checked out software available for the ELM for some time but its functionality used to be very limited due to the way that particular interface works.