I have a 2009 Mk2 Focus and have been experiencing intermittent issues starting the car for some time now. About 2 years ago the issue began, where sometimes the car would start without issue, other times it wouldn't tick over at all. Some research led me to believe the issue was with the instrument cluster (the battery was fine), so I sent it to get reconditioned.

 

After installing the refurbished cluster, the car worked fine for a little over a year, then the issue returned. I sent the instrument cluster back on warranty, but they tested it and said it was fine. I had the car checked over by an electrical specialist, who said there were no obvious issues with the battery, fuses, or wiring lume. The fault codes also all pointed to the instrument cluster (screenshot of codes attached). 

 

Sent it back again on warranty, but again it passed their tests.

 

I had the unit cloned to a second-hand unit I found online, installed that, but the problem still persists. So, either the second-hand unit had precisely the same issue (not impossible, given the apparent commonality of this issue in the Mk2, but still thinking it's unlikely) or there's another issue that is directly linked to but not within the instrument cluster. FYI, I have also tried with both keys and the issue persists, so no problem with the keys.

 

Any other thoughts? I don't want to spend too much time/money going down a rabbit hole of diagnosis, given the age of the car, but willing to explore a few more avenues before giving up completely, seeing as it is otherwise holding up well.

 

Thanks in advance

2009 will be a facelift model. I provide a repair service myself (https://www.ebay.co.uk/itm/314393033915), the cluster from the facelift model is the one I repair the most. It's very likely that the second hand replacement unit will itself need the cracked solder joint issue to be repaired.

Have you tried clearing codes at any point, for all I know those codes you're showing us could be old ones and irrelevant. Presumably these codes are from the original unit, what about the replacement?

The accelerator pedal position sensor is something that connects to the instrument cluster via it's 32-pin connector, as is the fuel gauge sensor (presumably what is referred to as 'fuel sender'), as is the PATS transceiver. Both CAN buses are also connected. Given that multiple things connected via the IC's connector are experiencing problems (broken circuit, no signal, invalid data), I'd very strongly suspect the unit those codes are from has been suffering from the common cracked connector joint problem. Again though, are those codes relevant or old?

The previous repairer could have just done a basic "reflow" (melting the existing solder back into place) of the existing crack-prone lead-free solder, so it could have just cracked again over time, though I'd be surprised that it lasted so little time (given it took years for the original cracks to develop). A better repair would be to have replaced the old solder with standard leaded solder which can withstand environmental stresses much better. They may alternatively have just dumped a lump of whatever solder they have to hand on top of the old cracked solder. I've handled a few units before that had previously been worked on by other repairers, including a big company, and been very unimpressed with the quality of work, so it's very possible that they did a poor quality job and it's failed, and quite spectacularly if all of those codes are relevant.

Why they are saying it passes testing if their repair has failed, I don't know. One possibility is that they've not really tested it at all and just don't want to accept fault and have to redo their work. Another possibility is that the faults simply don't show up for them. The cracks can be very fine after all and metal expands/contracts with temperature changes. Personally there's very little that I can practically do in terms of testing units and symptoms reported to me rarely ever show up when I power them on on my desk. I've no idea whether their testing ability may differ.

Or, maybe those codes are all old and irrelevant, in need of being cleared, the IC really is fine, and there's a fault elsewhere in the vehicle that's been missed.