Technical Engine cooling fan trouble - the right behaviour?

[nigelvan]

Vehicle: X250 3.0 2007 (Citroen version)
I'm troubleshooting a high speed fan error: when using the A/C in heavy traffic/hot weather the ECU threw a code on the high speed fan.
I hooked up MES to actuate the right relays and after some fiddling relay T06 came back alive and fan N012 kicked back into high speed (this is the fan on the left when facing the front of the car). Low speed actuates relay T07 and puts fan N011 in low speed.
So, when testing with MES: Low speed -> T07 -> activates only fan N011, High speed -> T06 -> activates only fan N012. At least, when triggering it through the software.
According to eLearn, this is not the right behaviour. when I look at the description and schematics of Diagram E5020, for vehicles with manual and automatic A/C.

Low speed should both activate T07 and T06 putting N012 in high speed and N011 in low speed. High speed additionally activates J028 according to the description:

But this is not what is happening in my van, so...
When I look at the simpler version for versions without A/C:

this explanation leads me to believe that either one fan runs at full speed, or both fans run at full speed (when high speed is requested), which is also not what is happening in my vehicle.


So back to my situation where either T07 is closed on low speed, but T06 is not, and T06 is activated on high speed, but T07 is not.
Maybe MES gives different commands than when the ECU itself determines which speed it wants depending on the conditions?

Bottom line is whether I need to look further into this issue, possibly troubleshooting an issue with relay J028 on the low speed N011 fan...

 

[Communicator]

Hi Nigel,

At least the x250 version of the eLearn schematic is an improvement on that for the x244, which is poorly drawn. eLearn for the x244 contains gross errors, perhaps there are some in the x250 version?

I agree with your interpretation.

Working from your posted copy of eLearn schematic, E5020:
Fan N12 switched on, via relay T06.
Fan N11 on low speed, via relay T07.
Fan N11 on high speed via relays T07 & J28.

I think that you have answered your question in your penultimate sentence. I suspect that MES deals with several models, it allows you to operate both fans, but does not fully replicate the ECU outputs.

For comparison my x244 2.8jtd does not have aircon, so no resistor O10, or relay J28. Only choice for the ECU is for one or two fans operating. MES would allow me to check the fans individually.

 

[nigelvan]

Hi Nigel,

At least the x250 version of the eLearn schematic is an improvement on that for the x244, which is poorly drawn. eLearn for the x244 contains gross errors, perhaps there are some in the x250 version?

I agree with your interpretation.

Working from your posted copy of eLearn schematic, E5020:
Fan N12 switched on, via relay T06.
Fan N11 on low speed, via relay T07.
Fan N11 on high speed via relays T07 & J28.

I think that you have answered your question in your penultimate sentence. I suspect that MES deals with several models, it allows you to operate both fans, but does not fully replicate the ECU outputs.

For comparison my x244 2.8jtd does not have aircon, so no resistor O10, or relay J28. Only choice for the ECU is for one or two fans operating. MES would allow me to check the fans individually.

So, if MES can't replicate the correct outputs, I have to drive the van to Spain where it's 45C now and run the A/C while driving uphill a mountain to get the high speed fan to activate.
No just kidding, I guess the best way to make sure is to supply 12V directly to J028, see if it actuates and put the N011 also in high speed. I think the schematic is correct but the functional description is not. Low speed according to the manual A/C version says both T06 and T07 are active in low speed mode. Which puts one fan on low speed and one on high speed. This really seems like a lot for the 3 liter, that engine is already a challenge to keep warm when you take your foot of the accelerator. And only one fan on low speed (through O010) already creates a noticeable air flow.
Thanks!

 

[nigelvan]

I dug deeper into the issue. Turns out the wire in the loom between B001 connector 28 and ECU pin 69 had snapped. Wasn't easy to find but after connecting two said pins between a multimeter and squeezing the cable loom the problem became obvious. Soldered the wire back together and I'm hopeful that will be the end of it...