Gl 420 SRS light

[Tony Mate]

My 56 reg GL 420 has the SRS light on. I have had it diagnosed by an auto electrician and he told me that it just needed to be reset. Due to illness in his family he could not complete the reset so I have had to take the car to another auto electrician / garage.

I have been informed by this garage that the SRS module is faulty and they can not reset it. The result a replacement which they have quoted £544 + Vat

I have two conflicting diagnosis. I have a Snap on diagnostic tool and that will not allow me to reset it could it be that the latest garage do not have the right equipment does it have to go to merc to have this type of light reset?

 

[David Richardson]

I think that it may only fully re set by either a MB dealership or an independent MB specialist who will access to a
'Star' diagnostic machine.

Once connected the Star machine will be able to fully diagnose the problem & it usually costs about £40 at an indie for their work

Others may advise you.

 

[Richard Moakes]

I find it hard to believe the module is faulty, what is needed is a diagnosis where the SRS module is queried for what is causing the error. Most OBD scanners can't do this, but either Star/Xentry or an Autel or iCarSoft can go deeper into the modules and find out what is causing the problem.



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[Tony Mate]

I find it hard to believe the module is faulty, what is needed is a diagnosis where the SRS module is queried for what is causing the error. Most OBD scanners can't do this, but either Star/Xentry or an Autel or iCarSoft can go deeper into the modules and find out what is causing the problem.



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I also find it hard to accept the module is faulty. The car had been sitting for six months and when I bought it the dealer advised it may need anew battery. I have had this tested and told the battery is fine. The third row seat right hand side is working electronically but does not lock and as a result I get a third row seat not locking error message. Could this perhaps be linked to the SRS light?

 

[Tony Mate]

I find it hard to believe the module is faulty, what is needed is a diagnosis where the SRS module is queried for what is causing the error. Most OBD scanners can't do this, but either Star/Xentry or an Autel or iCarSoft can go deeper into the modules and find out what is causing the problem.



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Thanks I will ask the dealer what he uses to scan the vehicle

 

[Tony Mate]

I also find it hard to accept the module is faulty. The car had been sitting for six months and when I bought it the dealer advised it may need anew battery. I have had this tested and told the battery is fine. The third row seat right hand side is working electronically but does not lock and as a result I get a third row seat not locking error message. Could this perhaps be linked to the SRS light?

 

[Richard Moakes]

I think you are on to something with that, it's highly likely that SRS will not "arm" if the seats are not confirmed as locked for safety reasons.

I would concentrate on that as a root cause, and you may end up fixing the SRS issue as part of this.

Either way, I think an in depth scan of the modules is going to help tremendously.



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[Tony Mate]

j

I think you are on to something with that, it's highly likely that SRS will not "arm" if the seats are not confirmed as locked for safety reasons.

I would concentrate on that as a root cause, and you may end up fixing the SRS issue as part of this.

Either way, I think an in depth scan of the modules is going to help tremendously.



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just booked it in to Staiths Garage in Newcastle upon Tyne called them had a good conversation and they seemed very helpful

 

[LostKiwi]

To reset SRS lights you need a dedicated MB code reader such as STAR (very expensive and complex!) the iCarsoft i980 (around £100-130) or iCarsoft MB-II (£120 - 150).
There are others as well (Carsoft and Autel for example) that may also be able to accomplish this.

A common problem on some models is damage to the occupancy sensor on the front seat. This can be caused by someone kneeling on the seat or placing a sharp object on it. If it is this then replacement involves stripping the seat and replacing the sensor pad. The other alternative is to fit an 'emulator' box which fools the SRS module into believing the front seat is always occupied. This is only an issue if you fit a child seat as the sensor would disable the airbag under those conditions.

I don't think the seat not being locked would cause an issue as it would then cause issues when you carry a load and have the seats flat.

 

[Mark A]

They can fail unfortunately. I had to get main dealer to replace mine on the 171 a few months ago. It was perfectly fine until the main battery died and a new one was installed. Then I had SRS light that wouldn't clear. My own copy of STAR indicated a communication issue with the airbag control ECU. Various garages and auto electricians looked at it but main dealer ended up replacing in exchange for lots and lots of beer tokens.