Hi All,

This subject come up before but out of ideas.

Initially I had intermittent problem of no start with engine malfunction - then it became permanent issue. I managed to pull code with odb reader

U0155 - Engine ECU Lost Communication with Instrument Cluster

I then had a good check of both engine and footwell fuseboxes and re-seated all the connectors i could - fault changed slightly to now tranmission malfunction and no start. I have also lost coms with the ODB port ( i have tried different readers including forscan) so I cant check for codes now - tried using reset on left stalk and key to position 2 - came up test - no codes.

I pulled out instrument cluster and re-soldered connector pins - no change - but I might checke the solder joints again. Any ideas where to go next please?

I just rechecked using left reset and key position 2 - i have codes E510/D900. PATS code is 1/6

 

Edited March 19, 20224 yr by Allan J
update of codes

Checking the resistance between pins 6 & 14 on the OBD socket might give a clue. It should read 60 ohms (ign off), and be steady when bashing the fascia near the IC and wiggling any suspect wires or connectors. There is a 120ohm resistor in both the IC and the PCM between these lines (HS-CAN bus), and so it reads 60 if the CAN bus has good continuity right between the two. They at each end of the bus, so it tests the full length.

E510 on the dash test is U2510 ( - Invalid security data received from powertrain ECU (PCM)), which stacks with your symptoms, and D900 is U1900, which is a general Comms error.

Hopefully it is a connection problem between the IC & PCM. There are at least 5 connectors (including the IC & PCM connectors) in this bus, so plenty of scope for problems! The resistance test does a quite good job of checking this link.

If the IC goes through all its self test stuff in that "secret menu", then that tests out quite a lot of it.

That leaves the possibility of a PCM problem, either inside the unit or its power supplies & earths.

Some diagnostic systems (eg. Delphi, I beleive) will talk to the IC & other modules even if the PCM is not working, but Forscan needs to make contact with the PCM before it will do anything else.

Had no start start, transmission malfunction and no OBD communication on partners 09 focus. The battery had been cooked by some idiot trying to jump start it. Got the connection's wrong way round. 1 fuse blown in engine compartment box and 2 in the interior box. New battery and fuses changed, all works well now.

Thanks to help from TDCI-Peter this issue was solved with reseating the connectors in passenger footwell and engine bay. Lots of info from Peter on this subject here https://www.fordownersclub.com/forums/topic/113709-mk2-focus-16tdci-wont-start-and-no-lights-on-dash/#comment-801952

Most useful thing to do is get a multimeter connected to the ODB port pins 6 and 14 and check the resistance as you reseat the connectors - 120 ohm is bad, 60 ohm is is all good.

 

By a miracle or two, full schematics for the Mk2 & Mk3 Focus are available on this site. Such things are very rare indeed.

A picture of part of the CAN bus layout (Mk2, page 25) is here:

It looks a bit complex to start with, that it is because it covers most available options. So read the sub-titles carefully, and select the appropriate parts, and join them together at the numbered connector pins.

The MS CAN bus is also there.

Mk2 Schematic:https://www.fordownersclub.com/applications/core/interface/file/attachment.php?id=42087

Mk3 Schematic:https://www.fordownersclub.com/applications/core/interface/file/attachment.php?id=42086

I have found these these documents to be quite accurate, including for the CMAX. Someone did find that the wiring colour codes did not stack up on the Mk3 1.6TDCI (DV6C) pages, but I am blaming the French for that. And why not, they blame us for plenty!