SRS control unit

ABecvar · Dec 4, 2017

Hi, took my 2003 Discovery 2 for its MOT with the srs light on. Put it through diagnostics and it was an internal fault with ECU. Tried to clear it
but it persisted so gave LR the serial number and was told part number (YWC106200), but they don’t make them anymore. Can’t find one anywhere. Took off centre console to check and the part currently fitted is YWC106600. Bought a second hand on eBay as loads of them but now fault says passenger air bag not configured. Local dealer says they can’t be reprogrammed. So I’m stuck with a car I can’t MOT cause there’s no part that’ll clear the fault. Any ideas????

brian47 · Dec 5, 2017

From what I've heard, a failure of the DCU is almost unheard of. The usual causes of a SRS fault are:-

A faulty rotary coupler behind the steering wheel, on the column connecting to the driver's airbag
A broken wire or damaged connector under one of the front seats which feeds to the seatbelt pre-tensioners
A pre-tensioner has operated at some time in the past and not been replaced
A damaged wiring or connector to the passenger's airbag

Obviously, there is always an exception which proves the rule, but from what I've read all it does during the start up and self test routine is that it checks that it can communicate in a very basic way with each external unit. It's unlikely that any of the airbags communicate with the DCU in any "intelligent" way. It's probably just a matter of the DCU electronically measuring the resistance of each circuit and confirming that the value is within preset parameters and the circuit is consequently sound.
I'd be interested to know exactly what diagnostics system was used to identify a faulty DCU.

ABecvar · Dec 5, 2017

Thanks for the info. I’m not sure the model of the diagnostic system, but it was at a locally well know Land Rover specialist. The original fault was “internal ecu fault” which seems very specific given the other faults I’ve heard of for the same issue. Now to have it say “passenger airbag not configured” from the same system makes me thin that the diagnostic system is reading the fault correctly, it is the part (the ecu) that is the issue, not loose wires, etc.
I feel that Land Rover have put me in a sh*t situation....

brian47 said:
From what I've heard, a failure of the DCU is almost unheard of. The usual causes of a SRS fault are:-

A faulty rotary coupler behind the steering wheel, on the column connecting to the driver's airbag

A broken wire or damaged connector under one of the front seats which feeds to the seatbelt pre-tensioners

A pre-tensioner has operated at some time in the past and not been replaced

A damaged wiring or connector to the passenger's airbag

Obviously, there is always an exception which proves the rule, but from what I've read all it does during the start up and self test routine is that it checks that it can communicate in a very basic way with each external unit. It's unlikely that any of the airbags communicate with the DCU in any "intelligent" way. It's probably just a matter of the DCU electronically measuring the resistance of each circuit and confirming that the value is within preset parameters and the circuit is consequently sound.
I'd be interested to know exactly what diagnostics system was used to identify a faulty DCU.

r the info

SRS control unit

ABecvar

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brian47

Well-Known Member

ABecvar

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