Our trusty 09 1.6 TDCI decided to die today. It's been 100% fine and we drove a few miles to a nearby beauty spot to walk the dog this morning. On returning to the carpark, I unlocked the car, got in and got Engine Malfunction.

Also got the centre Red LED flashing.

Checked battery. Bit low, it's still on its original battery, so tried jumping off another battery.

No change.

Tried disconnecting battery and then reconnecting. Still no dice.

Put ForScan on it. No comms to ECU????

Called AA. He couldn't start it either. No comms to ECU with his kit either.

Eventually he was able to talk to the dashboard and got U2510 and U1900 codes.

So either the ECU is toast or the Canbus has a fault on it or the Dashboard may have a fault?

There are no faulty pixels of the dash, but it does switch from showing mileage to ----------- before switching to Transmission Malfunction.

Sounds like Canbus or ECU fault to me but a quick google showed that the dash can cause these faults.

Anyone got any ideas before I dig deeper?

The AA guy checked the fuses but I'm going to double check them first.

 

I just tried smacking the dash, in case its a solder joint problem in the dash pcb. No joy.

After a bit of googling I checked the following: The Immobilser LED is flashing. If you wait for a minute, it signals a code. Mine is 1:6 so I believe this is a PATS code.

Also you can access the built in diagnostics by holding the reset button on the left stalk while turning the key from 0 to 2. I got DTC codes D900 and E510.

So I will do some more digging.

 

DTC codes D900 and E510 are exactly the same as U1900 and U2510.
Some of the can-bus seams to be working still. Otherwise the AA couldn't have read the 2 U codes.

So, it's probably not an ecu hanging up the bus, but a wiring problem in the can-bus somewhere between the instrument panel and the engine ecu and transmission ecu.
It's not between the instrument panel and the diagnostic connector. It is however also between the diagnostic connector and the engine and transmission ecu's.

 

Thanks oldford, I think the AA guy said he was able to get comms to the dash not the PCM. It took him a while to get codes out. I don't know too much about focus wiring (yet). I assume here is more than one canbus and maybe more than one on the OBDII port? I know some cars have K line along with canbus on the OBDII port.

I'm going to check the canbus impedance and take a look at it with a scope.

I'll pop the instrument cluster and check the connector soldering too.

 

Checked canbus with scope. Looks fine at OBDII port. Both busses.

60ohms and good signals.

Opened up instrument cluster. Found cracks on the connector pin solder. Re-soldered all the pins. No dice. Damn.

So what to try next?

 

The can-bus you need to check is connected in the diagnostic connector to pins 6 and 14. That's the high speed can-bus that connects to engine and transmission.
Could you attach photo's or screen shots from the scope?

 

Checked it at OBDII port and at PCM. Looks fine.

Power and grounds look OK at PCM too.

Makes no difference to car starting/symptoms if PCM is plugged in or not.

Maybe it's dead?

Canbus as PCM with PCM unplugged. Looks ok to me. 0v is at centre and both channels are 2v per div.

 

Tried to bench test the PCM, but it won't scan. Tried another PCM an it will scan fine on the bench with just power and grounds connected. So my PCM looks like it's dead. I'm going to send it off to ECU Repairs.