Hello all. 
I’ve had an absolute headache with a power steering malfunction issue with my Focus ST MK2.5 (2010), it was intermittent for a while but now remains solid. The power steering system has always performed as it should. 
I recently changed the battery as the old one was 9% health (charged new one to 100% before fitting) and by downloading FORSCAN I’ve been able to have a look at current DTC’s. One remains which is an Instrument Cluster fault U1900 (CAN communication bus fault) and run tests on the EPS and ABS systems, which work correctly.  However, when starting the vehicle the Power Steering Malfunction persists.
 

The RPM tachometer does not read correctly and sits below zero, it still works but doesn’t read the correct idle or driving RPM. 
Would this indicate a faulty cluster and need re soldered? 
Any advice or help would be greatly appreciated. 
 

(I am unable to attach FORSCAN photos as they are bigger than 2MB) 

One quick test if you bang the dash and any of the faults disappear (or get worse) that’s often a fair indication of the cluster needing repair. Also check if the foglamp LED’s still illuminate when you put your foglamps on.

That was the first sign of the issue on my ST - rarely use the fogs so wasn’t immediately obvious, but the cluster solder fault often first shows on pins at the ends of the connector such as the dogs. I got mine repaired before any further symptoms came apparent 

7 minutes ago, troy45 said:

One quick test if you bang the dash and any of the faults disappear (or get worse) that’s often a fair indication of the cluster needing repair. Also check if the foglamp LED’s still illuminate when you put your foglamps on.

That was the first sign of the issue on my ST - rarely use the fogs so wasn’t immediately obvious, but the cluster solder fault often first shows on pins at the ends of the connector such as the dogs. I got mine repaired before any further symptoms came apparent 

Hi mate, thanks for the reply.
Everything on the IC works and all lights work. I’ve had the cluster out and gave it a shake put it back in and everything seems fine. Apart from the RPM tach and the ESP light. I’m just dumbfounded, I’ve it booked into a garage for their opinion but trying to resolve it myself first. 

Hi Rhys,

Although this is a great forum if you have a Focus ST 5 pot you will probably get more answers/info off this site I have linked that specialise in Focus STs

https://www.focusstoc.com/forums/

Just make sure you post in the correct section

58 minutes ago, Rhyssimp said:

I’ve had the cluster out and gave it a shake put it back in and everything seems fine

If you disconnected and reconnected the main cable, or even shook it with the cable connected, the disturbance of the connector may have re-made the connections in the suspect joints. Unfortunately this will likely only be temporary and the only guaranteed fix is to have the whole connector socket resoldered. This means removing the old lead-free solder that's responsible for the problem and resoldering with leaded solder. Reflowing the lead-free solder is not guaranteed to give a lasting fix.

42 minutes ago, TrevorB said:

Hi Rhys,

Although this is a great forum if you have a Focus ST 5 pot you will probably get more answers/info off this site I have linked that specialise in Focus STs

https://www.focusstoc.com/forums/

Just make sure you post in the correct section

Thanks mate, just posted.

43 minutes ago, mjt said:

If you disconnected and reconnected the main cable, or even shook it with the cable connected, the disturbance of the connector may have re-made the connections in the suspect joints. Unfortunately this will likely only be temporary and the only guaranteed fix is to have the whole connector socket resoldered. This means removing the old lead-free solder that's responsible for the problem and resoldering with leaded solder. Reflowing the lead-free solder is not guaranteed to give a lasting fix.

Thanks for the reply I’ll contact an auto electrician.

@rd457 does a repair service for the cluster issues, definitely recommended 👍