Airbag light

[billykan]

Hello 

Airbag light came on a couple of weeks ago, And found the fault, corroded wire under the scuttle panel in the wiring loom. lasted about 2 week's,

Airbag light now back on, And getting this fault below
Permanent fault
communication on the DATAB wire of the airbag ecu

changed out the airbag ECU and still the same. checked the wire's to the BSI and BSF seem fine,

could i have a fault in my BSI unit?

[Sol]

Data B is probably one of the two CANBUS lines, normally I've seen them called CANBUS high and CANBUS low, there has to be a wiring or corrosion issue elsewhere. Could be at the BSI itself but could be hard to pin down. You can't just swap the BSI out, it's coded to the ECU and your keys.

[billykan]

Data B is probably one of the two CANBUS lines, normally I've seen them called CANBUS high and CANBUS low, there has to be a wiring or corrosion issue elsewhere. Could be at the BSI itself but could be hard to pin down. You can't just swap the BSI out, it's coded to the ECU and your keys.

CANBUS wire's be the red and white wire's?

[Romahomepete]

Did you check the connections under the drivers seat? they are rubbish, you may want to consider replacing them.

Peter

[brajomobil]

Canbus wires are always "twisted".
Wire colors are always different.

You can take any canbus wires and connect
them to different units just to rule out wire problems.

Best regards,
brajomobil

[Sol]

Yeah as brajomobil says, twisted pair. It's a serial Comms bus between modules.

[billykan]

Canbus wires are always "twisted".
Wire colors are always different.

You can take any canbus wires and connect
them to different units just to rule out wire problems.

Best regards,
brajomobil

Tried changing the canbus wire's about and airbag light still on.

[Sol]

There's a separate airbag ECU. The airbag isn't controlled from the BSI. What tool did you use to scan it? Best to use a Lexia interface with DiagBox as it's the dedicated Citroen software and you'd get a better idea of exactly where the problem lies. You will have at least 1 airbag, 2 in the car, the both front seats have the SRS firing modules in the seatbelt clip mounts. These all go back to the airbag ECU and it connects to the other ECU's using the red and white CANBUS wires.

You can't reverse the red and white wires as one is CANBUS high and one is CANBUS low.

[billykan]

There's a separate airbag ECU. The airbag isn't controlled from the BSI. What tool did you use to scan it? Best to use a Lexia interface with DiagBox as it's the dedicated Citroen software and you'd get a better idea of exactly where the problem lies. You will have at least 1 airbag, 2 in the car, the both front seats have the SRS firing modules in the seatbelt clip mounts. These all go back to the airbag ECU and it connects to the other ECU's using the red and white CANBUS wires.

You can't reverse the red and white wires as one is CANBUS high and one is CANBUS low.

Lexia was used and came back with, Permanent fault communication on the DATAB wire of the airbag ecu

[Sol]

Ok buddy, well if the CANBUS wires are intact and continuity is good from end to end on both wires, the only thing left is a faulty airbag controller I guess. I'd also think the airbag ECU is one of the few ECU's you can swap out without coding, as long as the part numbers match.

When you scan the airbag in DiagBox, does the airbag light flash and the dashboard beep 3 times? I expect not, since from the OBD socket you are communicating through the BSI to everything else over the CANBUS wiring. Worth trying a used unit from a breaker or ebay. Could resolve it pretty quickly.