Hi!

So im having an 2009 Ford Focus 1.6TDIC, wont start at all. PATS light is ON with 1-6. Fault codes are U1900 and U2510 in IC. There is no access to PCM. VIN number cannot be read. Wiring seems to be OK to ECU, atleast all 12V power and grounding. Also CAN hi/lo is OK. 62Ohm, when all attached. And 120ohm from IC and PCM. I tried with another PCM and everything remains the same. Can bus is fine when checked with oscilloscope. Every fuse is in place as should and are powered up, all relays work. IC has been repaired already.

I have literally checked everything. Any ideas?

29 minutes ago, ShovelHero said:

IC has been repaired already.

I'd say you still have an IC failure.

Was the instrument cluster fully refurbished or just the connector soldered ?

12 minutes ago, unofix said:

I'd say you still have an IC failure.

Was the instrument cluster fully refurbished or just the connector soldered ?

Instrument cluster was soldered. I forgot to tell that i also tried another IC. But it cannot be configured to the car because no comms to PCM.

Just checking with my limited knowledge, sorry to butt in... can (sorry for the pun) you communicate with individual modules (by disconnecting everything else and adding them in until the fault appears) and is the IC the only one that can't be contacted (meaning that module or it's connections is the fault?)
Dan (Diagnose Dan) has videos showing how he does this.

OR, if relevant:

 

Edited March 16, 20251 yr by Shearers
Added video link

7 hours ago, Shearers said:

Just checking with my limited knowledge, sorry to butt in... can (sorry for the pun) you communicate with individual modules (by disconnecting everything else and adding them in until the fault appears) and is the IC the only one that can't be contacted (meaning that module or it's connections is the fault?)

I haven't seen the videos.

A CAN bus consists of a pair of wires with a 120 Ohm resistor joining them together at each end (giving total resistance between the two wires of 60 Ohms). The purpose of the resistors is to suppress signal reflections. These resistors actually live within a module towards either end of the bus. Without those particular modules connected you may or may not achieve successful communication. Additionally there are typically multiple CAN buses, and there may be a module acting as a bridge between buses, and there are only so many buses that can be directly accessible from the diag connector. So it's a bit more complicated than you realise.

In the Mk2 Focus the IC is one of the special resistor-housing modules for both of its networks and may also act as a bridge. The GEM/BCM is the other for one network, and the ECU is the other for the other.

As an example of the importance of the presence of the resistors - cracked solder joints on the IC connector is a very common problem for Mk2/2.5 Focuses; the dodgy/broken connections to the special CAN bus resistors it houses for its end of the CAN buses can commonly cause module communication failures. (Which supposedly is not what is going on here).

19 hours ago, Shearers said:

Just checking with my limited knowledge, sorry to butt in... can (sorry for the pun) you communicate with individual modules (by disconnecting everything else and adding them in until the fault appears) and is the IC the only one that can't be contacted (meaning that module or it's connections is the fault?)
Dan (Diagnose Dan) has videos showing how he does this.

OR, if relevant:

 

 

12 hours ago, rd457 said:

I haven't seen the videos.

A CAN bus consists of a pair of wires with a 120 Ohm resistor joining them together at each end (giving total resistance between the two wires of 60 Ohms). The purpose of the resistors is to suppress signal reflections. These resistors actually live within a module towards either end of the bus. Without those particular modules connected you may or may not achieve successful communication. Additionally there are typically multiple CAN buses, and there may be a module acting as a bridge between buses, and there are only so many buses that can be directly accessible from the diag connector. So it's a bit more complicated than you realise.

In the Mk2 Focus the IC is one of the special resistor-housing modules for both of its networks and may also act as a bridge. The GEM/BCM is the other for one network, and the ECU is the other for the other.

As an example of the importance of the presence of the resistors - cracked solder joints on the IC connector is a very common problem for Mk2/2.5 Focuses; the dodgy/broken connections to the special CAN bus resistors it houses for its end of the CAN buses can commonly cause module communication failures. (Which supposedly is not what is going on here).

Thanks for answer. So i can connect manually to IC, ABS and GEM. But not pcm, and IDS tries to find vin from pcm but cant because no communication. I think that can bus is fine, because could it read couple of modules and not just one?

Could can hi/lo be partially disturbed? Like something blocks information from pcm but resistance is still good?

 

Running out of ideas 😅

Okay now i think im on trace. Resistance from can hi to ground and can lo to ground is 4 kOhms. It should be infinite or megaohms i think.

Some module must be shorted to ground even can resistance from hi to low is ok.

2 hours ago, ShovelHero said:

Okay now i think im on trace. Resistance from can hi to ground and can lo to ground is 4 kOhms. It should be infinite or megaohms i think.

Some module must be shorted to ground even can resistance from hi to low is ok.

Now im even more confused, i measured this from another similar focus. Resistance from can hi to ground is 7 kOhms. Same is in can low to ground. (This car works normally).

 

But on same year diesel kuga it is infinite resistance. Also in 2011 fiesta it is infinite reistance as it should be.

 

Edit: to clarify, measures are from OBD pins 6 and 14 to ground. 4kOhms on my car, 7 kOhms on a similar car. Kuga and fiesta infinite resistance.

 

As I said, Dan has had similar issue with multimeters in this one and several others where he investigates CAN problems.

I don't think there should be anything other than infinite resistance between CAN wires and Earth but that's just my guess and I don't like guesses so I'll have to leave it to you to review his work and decide from there?

I think in this one he uses a breakout box to check the CAN networks:

 

9 hours ago, ShovelHero said:

Now im even more confused, i measured this from another similar focus. Resistance from can hi to ground is 7 kOhms. Same is in can low to ground. (This car works normally).

Are you testing both the HS and MS canbus pairs ? Is each pair 60 Ohms ?

 

On 12/30/2024 at 3:10 PM, unofix said:

Time to get the multimeter out and start testing the Canbus systems. Both MS and HS should each read 60 Ohm.

There is one 120 Ohm resistor fitted across each pair of canbus wires at the start and finish of the network. So in effect two 120 resistors are fitted in parallel. If there is a break in the wiring then you will only read across one of the resistors which would give a value of 120 instead of 60 Ohms.

 

 

 

On 12/25/2024 at 11:41 AM, unofix said:

 

 

Solved! PCM was faulty, but also ABS unit was faulty. With new PCM but old ABS unit, CAN hi voltage was dropping to zero for about two seconds every now and then. I started unplugging components and after ABS unit, voltages didnt drop anymore.

With old PCM can hi voltages were fine but PCM itself didnt work.

 

After unplugging ABS unit, i could program new PCM 👍 No idea how so many faults at the same time. What a learning experience about CAN bus.