Citroen XM Forum

Hi Dean

Checked out V6 ECU's.
XM 1 no. 40 (31/10.1991) states all V6 ECU's are interchangable.
Not found any further changes.
Only the V6-24v had wiring any ECU differences by this date. I know this does not help pinpoint your current problem but it does tell you V6 ECU marking if you go the route of a swap for test purposes.
Elsewhere in the document it covers thermostat and thermal switch changes so I will scan and add that. John

citroenxm wrote:Is the fuel pump in the tank yur 2.0i one or a v6 one .. or are all lift pumps same spec?? Is it cutting out from over heating possibly if wrong spec? Just some thoughts..

Fuel pumps are all the same spec.

misha wrote:

citroenxm wrote:Is the fuel pump in the tank yur 2.0i one or a v6 one .. or are all lift pumps same spec?? Is it cutting out from over heating possibly if wrong spec? Just some thoughts..

Fuel pumps are all the same spec.

Brill Misha thats great to know!

swapped my temp sensor in the head out this evening as it seemed i had no fans working, it measures 1.77ohm @ 15C - 3.00ohm @ 100C which is the same as the replacement.

Only swapped it as I couldn't get the multimeter on it in situ and it's only a few minutes to swap, plugging the spare sensor in beforehand and warming it with fire brought the fans on pretty quick so reasoned the sensor fitted was duff, not so.

I can only assume the 2.0i rad fan bitron uses a sensor with higher resistance than the one fitted to the V6 or the coolant temp at the guage sensor happily gets to above 100C before the fans come on at even low speed with this engine which i find hard to believe, but if that is the case i will be modifying that sensor fairly soon.

D

I'm surprised that the resistance only moves a couple of ohms over that large temperature shift. Not seen such before; resistance gradient usually much greater. Perhaps John has some service data on that sensor.

I would have thought a temperature of 100c before fans come on is about right.

Dean wrote:swapped my temp sensor in the head out this evening as it seemed i had no fans working, it measures 1.77ohm @ 15C - 3.00ohm @ 100C which is the same as the replacement.

I think that you may have had you meter on the wrong range. 3k ohms would be about right.

xantia_v6 wrote:

Dean wrote:swapped my temp sensor in the head out this evening as it seemed i had no fans working, it measures 1.77ohm @ 15C - 3.00ohm @ 100C which is the same as the replacement.

I think that you may have had you meter on the wrong range. 3k ohms would be about right.

yes you are right, i may well have done but assumed the sensor was ok as it measured out the same as the spare and resistance continued to change as the sensor was heated.

I may try plugging in the Bitron controller from the V6 in place of the 2.0 one currently fitted and see if that brings the fans on earlier, or test the readings of the brown sensor from the 2.0 engine to see if it has differing values. Having the stat open at 87c (i think) but not bringing the fans low speed on untill over 100c just doesnt seem right, i would think somewhere between 90-95 is where low speed fans need to come on and 95-100c for high speed.

D

The 'stat opening temps and fan cut-in/cut-out temps are in the cooling system manual pages.

iirc. The Bitron box version controls the fan on/off temps, so swapping it may well make a change.