Citröen XM (1997) - Diagnostic port location

[Aretius]

Hi,

I have an old, but quite nice Citröen XM, 2.5 TD from 1997 in my garage. I've been thinking about turning into my daily drive - pretty cool. The ABS light is lighting up, though, and has been since I board it 3 years ago. The sensors, at least the rear ones, was changed by the previous owner, however the light is still on. - I hope it isn't the ABS computer that is dead...

Nevermind, I'm pretty sure there should be a diagnostic port somewhere. No idea where, though, and the internet isn't exactly overflowing with information about said port. I bought an adaptor (30 pin to OBD), but where to plug it in?

Anyone who knows about said subject?

Sincerely
Henrik
Denmark

[xantia_v6]

There is a little door in the panel under the steering wheel, the 30 pin diagnostic socket is hidden behind that.

[Aretius]

Right, quite easy to find, when knowing where to look. However, for some strange reason my Creader Professional CRP129 can't communicate with the port. The plug fits perfectly, but no communication. Even though the CRP129 says it has a XM entry; once in it you can scan the Engine and the ABS. Still, no communication.

Any idea why, or is just a question about the right fault code reader?

[wheeler]

In the under bonnet fusebox there is a green relay, pull it out & check the pins & plug for corrosion. You may find that some of the pins from the relay stay stuck in the plug. Causes no comms with ABS.

[Aretius]

Well well, that was all it took: cleaning the green relay. The ABS light went out as soon as the pins were clean.

Thank you very much. You've saved me a lot of hassle with that advice

[citroenguy]

To my knowledge only Lexia will communicate with non EOBD Citroëns.
Will even work on mk1 XM with 2-pin connectors for every computer

[wheeler]

Well well, that was all it took: cleaning the green relay. The ABS light went out as soon as the pins were clean.

Thank you very much. You've saved me a lot of hassle with that advice

Changed quite a few of them for this, was a fairly common problem back in the day. I would normally always replace the relay & the relay holder. A lot of the time they were that bad that the corroded pins would just break off & stay in the plug.

[Aretius]

If I may, I have another question - this time regarding the blower. See, the blower motor itself works fine. I believe the previous owner even changed it. But somehow the blower system lives its own life. Well, it does what I tell it to do (through the buttons), but the motor won't always engage right away. Say I want it to blow full power manually, then it may do it imediately, or it may take several minutes. Anyone who has experienced such an autonomous blower system?

[CitroJim]

To my knowledge only Lexia will communicate with non EOBD Citroëns.
Will even work on mk1 XM with 2-pin connectors for every computer

In my experience, a lot of Lexia clones and rip-offs can struggle with an XM (and indeed early Xantis or any other with the 30 pin socket)..

Best for these if you can find someone with a proper Citroen ELIT diagnostic machine...

An ELIT looking at an AX

The blower is under aircon ECU control so the dash controls only indirectly control it... The blower itself takes a LOT of current so the wiring - never the XMs strongest point - can have intermittent high resistances that can cause this sort of odd behaviour...

A good starting point is to monitor the voltages at the four pin plug on the blower speed regulator mounted in the blower motor housing...

A few threads dealing with Xantia aircon issues on this forum will give you the expected voltages on this plug under various conditions... This aspect of the XM is common with the Xantia as they use the same blower speed control module...

From there you should be able to work back and root out the problem...

[citroenguy]

To my knowledge only Lexia will communicate with non EOBD Citroëns.
Will even work on mk1 XM with 2-pin connectors for every computer

In my experience, a lot of Lexia clones and rip-offs can struggle with an XM (and indeed early Xantis or any other with the 30 pin socket)..

Best for these if you can find someone with a proper Citroen ELIT diagnostic machine...



The blower is under aircon ECU control so the dash controls only indirectly control it... The blower itself takes a LOT of current so the wiring - never the XMs strongest point - can have intermittent high resistances that can cause this sort of odd behaviour...

A good starting point is to monitor the voltages at the four pin plug on the blower speed regulator mounted in the blower motor housing...

A few threads dealing with Xantia aircon issues on this forum will give you the expected voltages on this plug under various conditions... This aspect of the XM is common with the Xantia as they use the same blower speed control module...

From there you should be able to work back and root out the problem...

Mine worked great on the ABS-module of a -93 XM a couple of weeks ago, but i tried it on an -91 BX and it failed.
For cars with 30-pin socket, the clone VCI or software usually isn't the problem. It is the OBD to 30-pin adapter that is not wired correctly.
I have a OE adapter and it works every time with my clone VCI and software

[CitroJim]

It is the OBD to 30-pin adapter that is not wired correctly.
I have a OE adapter and it works every time with my clone VCI and software

Yes, I've seen just that a few times when compared to my OE adaptor. All those I tried seemed to be wired differently in every case...

Some of the earlier Lexia clones, again very much in my own experience, could struggle with several variants of ABS units and Aircon ECUs...

I no longer have a Lexia... For my cars and those others I regularly deal with, the ELIT does the job perfectly...

It's useless on my AX though as it's totally ECU-free