SD Connect C4 can't connect win Smart 451

[SAMDoctor]

Hi. I have tried connecting my SD Connect C4 to a Smart 451, DAS can read VIN code but when connecting to the ECU it takes a long time and then ask to switch the ignition on.Key is on the ignition, tried switching it off and on bt no luck. On Smart 450 and 452 it works perfectly.

It seems there is some communication problem in the unit (Possibly the canbus circuitry), tried with two cars today and no luck. Also tried with another cable. Any idea wher to start looking?

[SAMDoctor]

Opened the mux and had a butchers on the relay board. Not the highest quality clone, the board have no chokes and Fujitsu relays. Cleaned some flux residue from board.
IMG_20190721_201142.jpg
IMG_20190721_201128.jpg

All the relays checked, coils measure close to 145Ω, terminals 2 and 3, 7 and 6 are connected when the coil is not energized. Have yet to test to power the coils and check 3 and 4, 6 and 5.

[SAMDoctor]

Forgot to update this thread.

Removed the 0 Ohm resistors and installed the common mode chokes. Now it connects to Smart 451 cars without issue.

[Julesd]

Hi SAMDoctor,
I have a Smart 5WK4 5090 V005
with no canbus communication,
can you give me any pointers to try please?
Thanks,
Jules.

[Julesd]

Just opened it up and seen breaks in the flexi joining the PCB's.
Please see photo attached.
Looks like it could be the problem?
What do you think please?

[SAMDoctor]

No, those are not an issue at all.

Was there any corrosion on the CPU board?

[Julesd]

Thanks for the quick reply.
Can't see any corrosion at all,very clean (Top board at least) can't see underside though

[SAMDoctor]

That SAM is a 450 model. There is no canbus to the obd connector, try with K line.

[Julesd]

It came in with no canbus issue. Are you saying it doesn't work on canbus, just Kline?

[Julesd]

Just stripped it down.
I see what you mean now, those gaps on the flexi are not tracks!

[Julesd]

Just seen some dry joints mainly on tracks coming from fuses.
Could it still be causing communication issues?

[Julesd]

Attached photo.
Thanks.

[SAMDoctor]

Yes, no canbus to the diagnostic connector. There are two different canbus on the SAM, one goes to the cluster and another one to the MEG (ECU)

[Julesd]

Thanks,
Could these dry joints be causing communication problems, even they they seem to be coming from fuses?

[SAMDoctor]

Those are not dry joints. Those are cracked, because of the vibration. They might be the reason, because the power to the ECU goes through these.