Volvo v50 abd and engine ecu no comms on diag

[morgano]

Hi

Any idea where to look for fault?

V50 1.6hdi fomoco edc16c34 ecu

Both engine and abs control units not answer on diagnose request.

Tired another ecu and another abs control unit, no joy.

Reviewed all wiring, feeds and can wires go correctly to all ecus.

First problem was car entered limp because abs comms drop while driving ramdomly.

Entered the workshop in working condition, took battery out and review all wiring harness. Repair some scratched insulation on some wires and when assemble back all and put battery car not start and no diagnose on abs and ecu.

After all this we are running out of ideas or paths to follow, so any good advice is welcomed.

Thanks

[morgano]

Guys from volvo say that is normal behaviour on that car, need send to dealer to realign all systems, but how can they realign ecu and abs if no comms on diag?

[smokin66]

does it have a Teves MK60 ABS pump?

[morgano]

does it have a Teves MK60 ABS pump?

Yes, it is teves mk60, why? is it relevant?

[smokin66]

i had problems once same car, known to have the faulty internal brake circuit pressure sensor, which I think is sometimes having a bit of a fit of reading total garbage - which then in turn sends the ECU inside the ABS/DSTC module wild and starts it throwing out data onto the CAN network - they're on the same "High Speed" CAN network as the throttle pedal, dashboard - which would explain the sudden jamming up of all these components at one (I think it uses CSMA/CD - any geeks amongst the ranks will get what I'm on about - it'd explain why the network jams) - The throttle not working is NOT a limp mode feature - no manufacturer I'm quite sure would or has ever disabled the throttle in an error situation. This would also explain the steering lock not functioning, the dashboard and also the Immobiliser fault - since it just cannot communicate. Which to me also is backed up by the Comms error fault code logged and APP Signal error.

[jurebv]

have you tried to communicate by can or kline?

[morgano]

Ecu on bench communicates, give good ID info on Kline and talks on CAN but only gives dots as info.

Abs unit also on bench not answer on can.

That is why i suspect there is some kind of proper dialog berween ecu and abs before they enable the can lines to talk to everybody.

Can lines go to all ecus, wires tested, but goes throw the cem, if cem is disconnected can bus is interrupted and not continuity with ecu or abs fron obd on can wires.

Curious thing is cem talks perfect with steering and is on the same can bus as ecu and abs.

This is a nightmare. :(

[morgano]

Diassembled CEM and read, diassembled ECU and read, syncro number matches both components, so its not syncro lost problem. There is also abs number present in ECU eeprom, so i guess abs id is matching too.

Next step will be refit CEM after clean and assemble it and if not working get a second hand CEM and try to clone it.