Technical Airbag ECU pin snapped and stuck in plug!

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Technical Airbag ECU pin snapped and stuck in plug!

iansl

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I think I may have found the source of my airbag light and I dont believe it could be any worse. I disconnected the airbag ECU and there are signs of corrosion in there and one of the pins from the ECU has broken/corroded into the corresponding plug.

I cannot think of any way to get this pin out of the plug as there is nothing to get needle nosed tweezers or pliers on to. I also suspect if I could get hold of the pin, there is a reason its come off, its probably corroded in some way to the plug on the other side.

This leaves me in a rather crappy situation. I cant buy a new ECU as it couldn't be plugged in anyway unless i can somehow replace this rather specialist plug. Its the type of plug with a lever to attach it too so I suspect its not a common thing.

The only thing I can think of right now is to open up the ECU and solder a wire to the corresponding connection inside and then try to find the corresponding wire in the loom to connect to. However I have just noticed that even though this is a 24 pin plug, in the loom that comes out of it there are only 6 wires. I have looked at the eLearn diagrams and as usual the colour codes and number of wires bear no resemblance to my van which has the following colours coming out of this plug....

Black going to earth on the van body.
Black,
White/Orange
Brown/Yellow
Brown/Grey
Blue/Yellow

I guess with just 6 wires coming out of a 24 pin plug I could be in luck and the pin that has snapped maybe is redundant? Although I guess I still have the airbag light so I suspect I am unlucky there.

For info, the pin seems to be number 7 of the grey connector.

If anyone has any idea of where I could buy a new 24 pin plug to replace the one I have, know which colour wire this pin corresponds to or any other suggestions to get me out of this mess I would appreciate your input.

Thanks people.

Ian

plug.jpgecu pins.jpgecu.jpgloom.jpg
 
Hi,
There are clear signs of corrosion in that connector. You need to replace it. As it's only six wires you could buy one from a breaker and splice it in. I've found breakers are happy to cut a plug off a loom for you. Thay need to leave about 6" of cable to make splicing easy. You will need a new ECU too.

Robert.
 
Hi Ian

That module seems to have had to put up with the fallout from wet boots and builder's tea !

I agree with Robert, your best bet is a connector from a breaker and solder/heatshrink the looms together. Once the contact plating has gone, you are very unlikely to be able to clean up that level of corrosion and achieve long term reliability. Unfortunately, you are also very unlikely to be able to source a new one on the open market as there are thousands of combinations and each type is specially commissioned by the vehicle makers.

It is quite possible that the corrosion extends within the module, I'm not sure if they are sealed like an ECU, probably not as they are supposed to live in a dry environment. A visual inspection will soon tell you.

Having said all that, if you really had to repair what you have already got I would recommend a very sharp meter probe which can pierce the cable insulation, and use an ohmmeter to determine which of your 6 wires goes to the broken pin. With that established, you could bridge across.

As a final tempering thought, the Airbag is a safety critical system and if you ever needed it you would want it to work. Equally, you don't want it going off when it shouldn't.......
 
Several you tube vids that can help , have you tried any of these guys , Ecu fix.com , Vehicle wiring products Derby , Auto Sparks,Notts , there are several others if you start digging ..best of luck .
 
Thanks for the suggestions. I have messaged several vehicle breakers to try to source a new plug and wiring. I have also managed to get hold of a kind of dental pick-type implement which I will try to see if I can fish the pin out with but I dont hold much hope as it looks to be welded in with corrosion and is in quite deep.

Once I have the wiring useable again I can begin to look at the ECU. Does anyone know if you just buy a new ECU and it will work off-the-shelf plug-and-play or do they need configuring in some way by CrashData to match the vehicle they are going in?

Thanks all.
 
Thanks for the suggestions. I have messaged several vehicle breakers to try to source a new plug and wiring. I have also managed to get hold of a kind of dental pick-type implement which I will try to see if I can fish the pin out with but I dont hold much hope as it looks to be welded in with corrosion and is in quite deep.

Once I have the wiring useable again I can begin to look at the ECU. Does anyone know if you just buy a new ECU and it will work off-the-shelf plug-and-play or do they need configuring in some way by CrashData to match the vehicle they are going in?

Thanks all.
A new one needs proxi-aligning to the vehicle. You can do that with MES or AlphaOBD. The alternative is for a company such as Crash Data to clone your old ECU onto the new one so that the vehicle recognises it as the original unit when it is installed.

When splicing in a new plug, you may already be aware, but stagger the joints so that they are not all bunched in one place. Fiat also say that only rosin core solder can be used for SRS system wiring repairs. The joints should be overlapped and mechanically crimped then sealed with a minimum amount of solder, and sheathed with adhesive coated shrink tubing ensuring that it overlaps the joint by a good margin.
 
Hi, thanks for the info on making the joints however I am hoping I wont need to as last night I took another look at the plug with my super-strength (+3!!!) readers on and discovered that it could be dismantled. It unclips and then slides apart. Then with some careful probing I managed to slide the connector out and get the pin out from there. I cleaned the plug up as best I could with meths and its now ready to accept a new ECU if that is necessary £368 from Crashdata.

However, I am not yet at that stage as I opened up the ECU and have soldered a wire onto the PCB in place of the missing pin. Having dismantled the plug I know what wire in the loom it needs to connect to so I am going to see if that gets me past the dreaded Airbag light. If not its new ECU time.

I know the description of the above will fill many of you with horror but its more an experiment rather than something I will rely on as a long-term-fix. The light may still be there anyway if the ECU needs resetting or there is some other fault I cannot find.

I will keep you updated.

Thanks once again to you all for your suggestions. Some pics are attached for your amusement!

plug open.jpgecu open.jpgecu back.jpg
 
Hi again

It doesn't look as if the corrosion has gone beyond the control unit's connector, which is good news.

"only rosin cored solder" By which they mean the normal cored solder used for electronics, which would be lead free these days. Only a numpty would use plumber's solder, but I guess they have to cover all bases ! Ever seen those US car restoration shows where they twist wires together and use a naked flame - haven't they heard of a soldering iron ?

Cleaning with meths is a start, but I strongly advise some proper contact cleaner like Servisol, which both cleans off deposits and leaves a protective film to ward off future corrosion. The best technique is to spray a bit in the socket and then keep mating and unmating the connectors to get a good wiping/cleaning action. I'm still a bit worried about the black state of some of those contacts, but it's hard to tell from a photo. Only you can judge if the cleaned up connector is going to give a good and long-term reliable contact.

By the way, the reason that corrosion is sometimes alarmingly bad on automotive DC electrical connectors is electrolysis. The presence of a 12 volts drives an electrical current through the contaminated water (electrolyte). You then have a plating bath situation, with metal deposited in one place and eaten away at another. The corrosion would probably happen without 12 volts present, but at a much slower pace.
 
Hi Anthony, thanks for all the information and clarifying the solder. I have done a reasonable amount of soldering in my time but was not aware it was called rosin cored solder. I may order some Servisol. I assume its different from standard WD40?

I am not able to test if it has worked yet as my instrument panel is currently being repaired. I am hoping I will have it back early next week and then I can see if the airbag light has gone off or not.
 
Hi. The full name is Servisol Super 10 Switch and Contact Cleaner. It is designed for the job, and a 200 ml spray can costs about a fiver and will last you for ages.

WD40 is a light lubricant/water disperser which is not the same thing at all.
 
Ahhh, okay ordered a can so I will do it this weekend.

Thanks, Ian
 
Hi all, I cleaned up the contacts as best I could with Servisol and an "interdental cleaning brush", connected it all up with my new wire to replace the missing pin but still no joy unfortunately. I guess either the ECU needs resetting or binning.

My next and last chance is a local auto-electrician and then if he is unable to reset it, I will have to try a brand-new ECU.
 
Hi all, just to let you know that I invested in MultiECUScan software and associated cables and found that I couldnt see the ECU to reset any errors. It just didnt show up as a module that is present in the vehicle. I phoned my local auto-electrician who said if thats the case then I need a new ECU. CrashData had stock of the ECU's and as I happened to mention I had the MultiECUScan software they sold me the ECU unprepped and didnt need my unresponsive one. I then installed it and used MultiECUScan to proxy-align everything and finally the damned airbag light was gone.

Just in time for my MOT on Monday.

Total costs - MultiECUScan + cables £85, New Airbag ECU £285 - total £370 to turn the airbag light off - heart-breaking but needed to be done. I just hope it doesn't fail in the future.

Many thanks to all the great forum members for your advice and ideas.

Until next time!

Ian
 
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