Airbag ECU/CrashData

[Nigel Crompton]

I had my Hyner's starter battery disconnected whilst I fitted a second domestic battery and some other stuff. Due to the weather and working in the open this took 6 days .... on re-starting I got the Airbag warning light. Doh, won't do that again ...

Anyway, ECU posted to Crashdata 23/12 for next day delivery, delivered at 9 something on Xmas Eve morning, dropped on my doormat at 1300hrs today. Now fitted and working. Excellent service.
MOT on 02/01/20 fingers crossed

 

[Hettie's Crew]

We too had excellent service from Crashdata, unfortunately ours needed replacing though due to corrosion (£300)
Our light came on when leaving our pitch at Peterborough Show last year after spending four nights ‘off grid’. We have solar that gives a 1amp charge to the starter battery so the battery is never low.
The year before we had a duff starter battery and the van spent a few days with no battery connected without issue.
I’m not quite sure of the do’s and don’ts regarding the starter battery and the airbag ECU. You have to disconnect the starter battery from time to time and shouldn’t expect it to damage anything.

 

[tacr2man]

SRS ECU should not be bothered by being disconnected , and have never had problem with one that has been in a vehicle with battery going flat, and thats been on quite a few vehicles over the years .

 

[Nigel Crompton]

SRS ECU should not be bothered by being disconnected ...

But they can be, as a few Funsters can attest (and, anecdotally, so can CrashData)

They maybe have a backup battery or rechargeable onboard that keeps 'em alive when the starter battery is dissed. Mine would be nearly 5 years old ...

 

[Deneb]

But they can be, as a few Funsters can attest (and, anecdotally, so can CrashData)

They maybe have a backup battery or rechargeable onboard that keeps 'em alive when the starter battery is dissed. Mine would be nearly 5 years old ...

It's important on modern vehicles to allow the canbus network to go into sleep mode before disconnecting the vehicle battery. The ECUs have to shut down in a similar way to your PC to avoid corruption of volatile memory, which I understand is one of the common causes of the SRS ECU failure.

The system shuts down approximately 3 minutes after closing the driver's door, provided that all other doors are shut, the key is removed from the ignition and nothing is connected to the diagnostic port.

So to be absolutely sure, you need to prepare the vehicle for battery disconnection by removing the floor cover, then get inside and follow the safe shutdown procedure before disconnecting the negative terminal without opening any doors. Once that's done you can go back outside and access the battery through the passenger door, but opening any doors before disconnecting the battery will wake the system up again.

Similarly on reconnecting the battery, negative cable connection should be done from inside with all the doors shut. Wait at least 10 seconds after reconnection, then turn on the headlight switch before switching on the ignition.

You can get away with not following this procedure 9 times out of 10, but if you want to be safe, it's the recommended method. Every time you switch off the ignition then shut the driver's door, the vehicle spends a few minutes putting the system into sleep mode to minimise current draw whilst it is parked. Part of that involves writing the current state of various ECUs into memory. It is interrupting that process which can lead to problems.

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[Nigel Crompton]

I had done that very thing - dissed the -ve via the passenger door. Twice.

 

[Deneb]

I had done that very thing - dissed the -ve via the passenger door. Twice.

Nigel, if you disconnected the negative via the passenger door, you had the door open. You should disconnect it from inside the van with all the doors shut, ignition off, nothing in the diagnostic port and at least 3 minutes wait after shutting the doors. Only after disconnecting the negative lead should you open the passenger door and carry on from outside.

 

[MC 55 FUN]

But they can be, as a few Funsters can attest (and, anecdotally, so can CrashData)

They maybe have a backup battery or rechargeable onboard that keeps 'em alive when the starter battery is dissed. Mine would be nearly 5 years old ...

When our airbag ecu failed & was replaced under warranty by Peugeot we were told by the Group Service Manager that low cranking voltage can cause the ecu to fail, not resting voltage, but low voltage when actually turning the key when starting the vehicle, not sure if this was the cause of our issue as we were never told why it failed.

 

[dosser]

I had my Hyner's starter battery disconnected whilst I fitted a second domestic battery and some other stuff. Due to the weather and working in the open this took 6 days .... on re-starting I got the Airbag warning light. Doh, won't do that again ...

Anyway, ECU posted to Crashdata 23/12 for next day delivery, delivered at 9 something on Xmas Eve morning, dropped on my doormat at 1300hrs today. Now fitted and working. Excellent service.
MOT on 02/01/20 fingers crossed

Hi Nigel having exactly the same issue after installing 2 new hab batteries. Did you get the system scanned to let you know what the issue was pinpointing the ecu or did you just send the unit away?
Think im going to get the mechanic i use to see if he can see what the problem is first.
Cheers.

 

[Nigel Crompton]

Hi Kenny ... I got my local auto electrical who lives around the corner to plug his box in, but results were inconclusive. As I was desperate to get not done and clear off to sunshine I just sent the ECU off ...

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[Hettie's Crew]

When ours went it couldn’t be read because it was dead, unfortunately I’d forked out to buy a scanner and it just kept saying not recognised. I was hoping it would be simple dodgy connection, but no.

 

[dosser]

Thanks Nigel, will get the garage i use to plug it in and see what they come up with, will also contact crashdata and ask their advice as well.
Thanks for the info.

 

[dosser]

When ours went it couldn’t be read because it was dead, unfortunately I’d forked out to buy a scanner and it just kept saying not recognised. I was hoping it would be simple dodgy connection, but no.

Thanks i was convinced it was a connection under the seat been under and round it checking. When i saw this thread didnt realise having disconnected the battery it could cause this issue.

 

[dosser]

Hi Kenny ... I got my local auto electrical who lives around the corner to plug his box in, but results were inconclusive. As I was desperate to get not done and clear off to sunshine I just sent the ECU off ...

Did the same Nigel got the garage i use to scan it just incase he could reset it, came up as an internal error in airbag module. Sent it off to Crash Data Reset in Washington all in with postage £40. got it back within 2 days reset and fitted back in the van.
Will be more careful if i need to disconnect the battery again.
Thanks for the info.

 

[Gellyneck]

Started motorhome to take for MOT and the airbag, child seat fitted, seatbelt off warning lights stay on and milometer flashing.
Took to the MOT station and got them to look at the problem rather than MOTing as it's a failure scenario. They came up with a airbag control unit B0100 fault on OBD and they couldn't reset so I posted off to Crash-Data Repair on Friday @ 19:00. Received back on Tuesday @12:00.
Refitted and all good. Flew through it's MOT today!

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