[Schmill]

So my 2012 Mk3 Focus flagged up a fault "Tyre Pressure Sys Fault - Service Required" and nicely lit up the ABS, traction control, and hill-assist lights yellow on the dash.
Got home, plugged in the elm and ForScan tells me its the rear right wheel:

(The other two code of C003A are "mechanical fault" and "incorrect sensor" but I suspect the "short to ground" is causing these)

Its intermittent, since it will clear itself from the dash (and then reappear at some point later) and similarly if you clear the DTC it will come back eventually.

Looking in the Helm Shop Manual it indicates to do point test 7 and refers to C440-1 and C440-2:

I'm assuming this is a connector - but does anyone have any hints on how I go about locating this connector? The ident is great, but it doesn't mean anything to me in terms of location etc.
Either that or any hints on where to look if this is a known issue of wear or chaffing on these wires?

Thanks in advance!

 

[Schmill]

I also find this is the same Helm manual... I have no idea where these wiring diagrams are though, I don't find them in the Helm manual (or at least in the download that I have )

I'm gonna go have a look and poke around the rear right wheel, but being intermittent I'm expecting a struggle

 

[Master-of-none]

C440 & C426 are simply the nearest connectors to the sensors.

 

[Schmill]

Thanks, where did you get this diagram?
I thought I had one, but could really do with a wiring diagram 👍🏻

 

[Mondygeek]

Enjoy!
Thank me later 😉

 

[Schmill]

Enjoy!
Thank me later 😉

Thanks @Mondygeek - but either I can't find it or else this document doesn't contain the two connector numbers I was referring to? (Although hopefully very useful for everything else!)

@Master-of-none - Where did you get the colour diagram from? It looks exactly what I was looking for in this case.

 

[Mondygeek]

This may help. Shows wires, what colours each wire, and the plugs from each wheel speed sensor to the abs unit

 

[Schmill]

This may help. Shows wires, what colours each wire, and the plugs from each wheel speed sensor to the abs unit

Thanks - is that from the PDF you shared earlier? - I'm not sure if I'm really rubbish at finding the right page in the wiring PDF or if you have another source you are getting these other images from?

I did some measurements on the car, and from what I can tell it seems ok, which is typical. Judging from the dash lights its an intermittent short, and I'm guessing it "isn't" at the the moment. complete pain since I don't know if I should be looking for a chaffed wire somewhere (sounds like a nightmare) or if these wheel sensors can / do go intermittently short?

 

[Mondygeek]

Yes from the same pdf

 

[Master-of-none]

A few cells were shared by someone on another site many years ago...
It was just luck that cell 42 was available .

 

[Schmill]

Both sensors showed the same value on a simple resistance check - so decided to swap them over and see if the fault moved with the sensor.
Car is currently up on wheel ramps (stationary!):

Apparently the rear left is now doing 57kph....

I think a new sensor is in order, and hopefully that will fix it 🤞