Fiesta 2008 revmeter failure MIL ON

[Timbo]

Hey guys.
I'm new to this forum and I'm from germany. I hope my english is well enough

My girlfriends fiesta's doing bad:
Specs: 07/2008, 8566 ACI 1.3 51KW (69HP)
suddenly the revmeter started to fail from time to time (of course it started to occour when I was driving the car...)
Some days later the MIL started to light up.
I had a look with my OBD and it said crankshaft position sensor failure (P0335 in PCM)
And, additonally, the IC give me 2196 (bad/wrong rev signal)

While reading the motor rev through OBD everything looks good.
Every results from OBD looked quite plausible, only temperature seems to have an offset of +15 degrees celsius. (i don't care atm)

The rev meter from time to time suddenly is starting to work again, mostly for a section or a fraction of it. (like having a lose connection or so)

What I checked:
-Changed crankshaft and camshaft sensors. Checked wiring to PCM with multimeter.
-Checked crank and camshaft sensors with oszilloscope (directly on sensors while they were plugged in and through OBD too)
-Crankshaft has a smooth and pretty sinus curve.
-Camshaft looks plausible as well, but signals more square. (but alternates plausible I would say. No professional on this point indeed)
-The rev gauge is working properly.
-The instrument panel is connected properly.

So from this point on I suppose the PCM to be gone
Maybe it could be the instrument as well?

The car is working like it was nothing btw.

To change the PCM or the instruments panel I need to readjust the immobiliser?! But how?!
I'm equipped with forscan btw.

Thanks in advance

 

[scotman]

Check ground connections! It is a increasingly common issue for Fiesta owners. Some Mil are activated because of sudden loss of power to certain sensors and or processors.

 

[Timbo]

It don't believe in this, to be honest. If it was a ground problem, some sideeffects should be seen too.

But I'll check this.
Do you know which points to check and where they are?
I only know about the points below the battery.

In the meantime I swapped the IPC's, but it didn't fix the problem.

I assume the problem lays in communication between PCM/IPC.
I don't know if the IPC is getting the rev information directly from the PCM or through OBD, do you?
Maybe there is like a dedicated wiring from PCM to IPC (which could be damaged) to feed IPC it with rev-information?

Reading through OBD the rev informations perfect.

The error P0335 always comes with a code that tells communication error: IC DTC U2196-60 Invalid RPM data.

So far...

 

[scotman]

I would be looking for the ground connections from the cluster Harness. I suppose that the Revmeter (tachometer) itself would be the next item to check. Is it getting a consistent signal when the engine is started and running?
It's not common for the instrument to fail. That's why I start at the power supply and grounds, then I check connections condition.
It's possible that a CPS is failing. But you say that it is running and starting as normal.
If you have FORSCAN connected, you should be able to see if it has a failed communication in the canbus. I believe that is the source of the MIL.
I am presuming that you have a fully charged battery that has been load tested?

 

[Timbo]

Battery is fine.
Checked wiring and grounding as far as I was able to follow the cables from drivers seat. I even tried to shake the wiring and the plug while the car was running without any effect.
Instrument cluster got replaced, but didn't change anything.
With forscan it says communication failure, indeed.
Is there a dedicated wiring for the Rev signal or is the IC feeded through OBD?
Anyone got wiring diagram or further informations for me? Best regards