SRS ECU Internal Fault

Derek Ward · Mar 11, 2015

Hi Guys
I've had a faulty alternator for a little while which I've just replaced. However, (also a little while ago) it threw up a SRS warning light and Airbag Fault message which I put down at the time to either the duff alternator or flat battery. After changing the alternator, accessing it with a Faultmate showed 3 error messages:
The airbag control unit has detected an internal fault.
Low voltage
o/c lamp
I've cleared the last two OK but cannot clear the internal fault one.
Has anyone had this fault before and been able to do anything with it or is a replacement ECU the answer? Also, I see there are two different types on fleabay. When did they change? Vehicle is a 1998 4.6.
Thanks.

wammers · Mar 11, 2015

Derek Ward said:
Hi Guys
I've had a faulty alternator for a little while which I've just replaced. However, (also a little while ago) it threw up a SRS warning light and Airbag Fault message which I put down at the time to either the duff alternator or flat battery. After changing the alternator, accessing it with a Faultmate showed 3 error messages:
The airbag control unit has detected an internal fault.
Low voltage
o/c lamp
I've cleared the last two OK but cannot clear the internal fault one.
Has anyone had this fault before and been able to do anything with it or is a replacement ECU the answer? Also, I see there are two different types on fleabay. When did they change? Vehicle is a 1998 4.6.
Thanks.

Changed in 1999 with the addition of air bags in the seats. But changes before that, crash sensors moved from front of car to inside ECU so make sure you get the correct one.

Derek Ward · Mar 12, 2015

Thanks Wammers. I was hoping to get one before taking the centre console in bits but looks like I'll have to do that first.

mozz smith · Mar 12, 2015

hi Derek , had same problem recently , on srs light showing !!!!! after getting top advice off wammers , take key out of ignition then access yellow cable connector under both seats uncouple clean and dry use electrical contact spray not wd40 , then light on dash should disappear . apparently when you move seats back and forth continuously ie changing driver as we do !!!!! it sometimes stretches the cable or catches on something under the seat and loosens the contact connectors !!!!! if the light ( srs ) doesn't clear the need to use diagnostics to clear faults etc,, hope this helps its a quicker cheaper option than going ecu route , unles s that is if its fecked ,, regards mozz oh and to wammy as well x

wammers · Mar 12, 2015

mozz smith said:
hi Derek , had same problem recently , on srs light showing !!!!! after getting top advice off wammers , take key out of ignition then access yellow cable connector under both seats uncouple clean and dry use electrical contact spray not wd40 , then light on dash should disappear . apparently when you move seats back and forth continuously ie changing driver as we do !!!!! it sometimes stretches the cable or catches on something under the seat and loosens the contact connectors !!!!! if the light ( srs ) doesn't clear the need to use diagnostics to clear faults etc,, hope this helps its a quicker cheaper option than going ecu route , unles s that is if its fecked ,, regards mozz oh and to wammy as well x

No seat bags on a 1998 car Mozz.

ovalandrover · Mar 13, 2015

wammers said:
No seat bags on a 1998 car Mozz.

but there is a rotary coupler connection under the steering wheel that can work loose

Datatek · Mar 13, 2015

ovalandrover said:
but there is a rotary coupler connection under the steering wheel that can work loose

Which would have shown on diagnostics

stopover · Mar 13, 2015

if you have an SRS light on all the time, whatever you do - as advice above, it could also be one of the SRS bulbs has gone. If one lamp fails the DCU will illuminate the other bulb permanently to indicate that a system fault is present. ie warning lamp bulb failure.

wammers · Mar 13, 2015

stopover said:
if you have an SRS light on all the time it could also be one of the SRS bulbs has gone. If one lamp fails the DCU will illuminate the other bulb permanently to indicate that a system fault is present. ie warning lamp bulb failure.

Would that come up on diag as an internal fault or an open circuit fault? Not sure to be honest. On SPS2 1999 on there are things you can look at. SPS1 you can only read faults.

stopover · Mar 13, 2015

wammers said:
Would that come up on diag as an internal fault or an open circuit fault? Not sure to be honest. On SPS2 1999 on there are things you can look at. SPS1 you can only read faults.

Good point. Last year I had the SRS light on all the time after the initial warning lamp test. I tried all the underseat connectors etc etc but had no luck so put on TestBook. I can't remember the fault code recorded so will have a look at my sheets to see if I recorded it and get back to you on that one if I did - have a feeling it showed both lamps a/b and stated which was open circuit. I replaced both bulbs from a spare instrument binicle but no luck so tried some more bulbs from that but it still persisted so got an instrument binicle from a Classic and popped two bulbs off that - worked and no trouble since.

Derek Ward · Mar 15, 2015

Hi Guys
Thanks for all the info above. It did initially come up with an o/c bulb but this cleared using the Faultmate. As Wammers says too, there ain't no seat airbags on a '98. Also, I think the rotary coupler would show up on the diagnostics. In the end, I got a replacement ECU from our good sponsors Emmotts (£20 and next day delivery - can't grumble at that can you!). This has now cleared the SRS light and Airbag warning message so job done. I can get it MOT'd now

A bit of a palaver getting the console out but a good chance to clear out all the crud that seems to accumulate down the side of the seats etc.
Thanks again.

SRS ECU Internal Fault

Derek Ward

Active Member

wammers

No longer with us, RIP

Derek Ward

Active Member

mozz smith

Well-Known Member

wammers

No longer with us, RIP

ovalandrover

Well-Known Member

Datatek

Well-Known Member

stopover

Active Member

wammers

No longer with us, RIP

stopover

Active Member

Derek Ward

Active Member

Similar threads