Technical Airbag - Front Crash sensor
- Thread starter Twincam1986
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Technical Airbag - Front Crash sensor
Twincam1986
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I know that, but should I leave the ECU unplugged permanently, if it's thinking it's 'plausable' that I've had a crash? I don't want a face full of airbag if I hit a speed bump!
No, it's a fail safe system. Relivent sections will be disconnected atm.
I disconnected the plug under the drivers seat and this is the fault code MultiECUscan gave me ..
0E so deffinately no "P" or "U" prefix ..
0E so deffinately no "P" or "U" prefix ..
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If the airbag light is showing, it is telling you that something wrong, and it's not going to go off in an accident. That's what the warning lights telling you.
wrong...
The airbag light tells You there is something wrong... The ECU goes into Fail safe mode so that the airbags will trigger in the event of an accident
The airbag light tells You there is something wrong... The ECU goes into Fail safe mode so that the airbags will trigger in the event of an accident
Not the airbags linked to the error. IE front crash sensor fault, front airbags will not deploy. However if the side airbag system is fault free then the side airbags will function without issue.
learn something new every day
Yep you do I thought all the airbags and SRS was disabled. Not just the ones linked to the fault, so if the side airbags go off with the light on, would the seatbelts fire also, and then why on the Brera I bought damaged the passenger bag had gone off, but the belt on that side had not, obviously the ecu tells when the seat is occupied, so why then fire the passenger bag and total the dash, weird, or just a way to write off cars and sell more, cynical I know but I priced the stuff new from Alfa, eye watering prices.
On some earlier airbag systems yes.
Twincam1986
New member
Just a quick update on this...
It went back to Fiat on Thursday for them to investigate further. They could not get the fault to clear. He said he checked the wiring to the sensor and there has been a repair there in the past, but the resistance reading is spot on, so doesn't see that this is the problem.
He thinks the problem lies with either the replacement crash sensor or ECU (both used parts). He's said if I bring it back on Monday, he'll have another Stilo in with known, good parts, so he'll swap them for me to see if the code will clear. Obviously, I'll update when this has been done.
Personally I think it'll be this repair to the wiring that's the problem, regardless of resistance readings. Does anyone know if this section of the loom can be purchased, or is it a major task? If it is, it'll be bye bye Stilo.
It went back to Fiat on Thursday for them to investigate further. They could not get the fault to clear. He said he checked the wiring to the sensor and there has been a repair there in the past, but the resistance reading is spot on, so doesn't see that this is the problem.
He thinks the problem lies with either the replacement crash sensor or ECU (both used parts). He's said if I bring it back on Monday, he'll have another Stilo in with known, good parts, so he'll swap them for me to see if the code will clear. Obviously, I'll update when this has been done.
Personally I think it'll be this repair to the wiring that's the problem, regardless of resistance readings. Does anyone know if this section of the loom can be purchased, or is it a major task? If it is, it'll be bye bye Stilo.
Twincam1986
New member
Ok, I decided to check out this 'repair' to the wiring (which turned out to be nothing of the sort). After what I've found, I'm after some help again! Firstly, here is the front crash sensor, located on the slam panel (the red/white wiring underneath is completely seperate, but the pic makes it look connected):
The wiring to the front crash sensor begins from a section of loom just to the left of the engine ECU, behind the passenger side headlight (it's the wiring starting in middle, then going to the right of frame, it's meant to be in that black plastic jacket.)
At this stage, there appear to be 4 wires: blue/white, purple/black (2 of) and plain blue. Then, on their way to the crash sensor they split. The blue/white and purple/black run to the front crash sensor (you can see them going into the plastic jacket, which then heads down) and the blue and purple black run to...
Ah...err nothing. They are bare and open (as you can see next to the engine cover)!
At one point, the wiring going to the crash sensor clips onto the fan housing to keep it out of the way. Just underneath this is another clip with section of plastic jacket, which logic would dictate is where this other section of wiring should head to. On my car, this section of jacket (pictured) is all that's left (the top section then runs to the crash sensor).
Can anbody tell me what this section of loom is (the 2 wires that on my car are disconnected), what it's for or where it's meant to go? If someone could have a look on their car I would be very grateful. Just to clarify, the other two wires definitely run to the crash sensor:
and are unbroken, yet it's still throwing up this error code, so this other bit of bodged wiring must be where my problem lies. I just don't know what it is or what it's for!
I've tried to make this as clear as possible, but obviously this is difficult, so if it's unclear please say and I will add more info where needed.
Thanks
The wiring to the front crash sensor begins from a section of loom just to the left of the engine ECU, behind the passenger side headlight (it's the wiring starting in middle, then going to the right of frame, it's meant to be in that black plastic jacket.)
At this stage, there appear to be 4 wires: blue/white, purple/black (2 of) and plain blue. Then, on their way to the crash sensor they split. The blue/white and purple/black run to the front crash sensor (you can see them going into the plastic jacket, which then heads down) and the blue and purple black run to...
Ah...err nothing. They are bare and open (as you can see next to the engine cover)!
At one point, the wiring going to the crash sensor clips onto the fan housing to keep it out of the way. Just underneath this is another clip with section of plastic jacket, which logic would dictate is where this other section of wiring should head to. On my car, this section of jacket (pictured) is all that's left (the top section then runs to the crash sensor).
Can anbody tell me what this section of loom is (the 2 wires that on my car are disconnected), what it's for or where it's meant to go? If someone could have a look on their car I would be very grateful. Just to clarify, the other two wires definitely run to the crash sensor:
and are unbroken, yet it's still throwing up this error code, so this other bit of bodged wiring must be where my problem lies. I just don't know what it is or what it's for!
I've tried to make this as clear as possible, but obviously this is difficult, so if it's unclear please say and I will add more info where needed.
Thanks
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Twincam1986
New member
Anyone any idea?
Twincam1986
New member
That's the one. That'll explain my 'alarm fault' message on startup then!
This loom has been messed with. Can this section be bought or would I have to replace the whole thing to clear the airbag fault?
This loom has been messed with. Can this section be bought or would I have to replace the whole thing to clear the airbag fault?
The alarm wiring has nothing to do with the airbag wiring, so that wouldn't cause your fault.
The only part of the wiring that's available seperately is the part from the bonnet switch to the black connector shown in my picture. That part comes with the alarm equipped bonnet catch.
The only part of the wiring that's available seperately is the part from the bonnet switch to the black connector shown in my picture. That part comes with the alarm equipped bonnet catch.
Twincam1986
New member
It must be something to do with this section of loom that's causing the issue, as I've ruled everything else out. The error code is 'front crash sensor - plausability'.
I've tried a known good crash sensor on my car and the code still won't clear. I've tried my crash sensor on another car and it doesn't produce a fault code on the other car.
I've tried 2 different airbag ecu's, (same part number) and both show the same fault code and it will not clear.
I can't see any break in the wiring from the crash sensor to the rest of the loom, but becuase there is damage to the alarm wiring in the same area, it must be damaged somewhere, which basically means it will be incurable without replacing the loom, which to do so would write the car off.
I've tried a known good crash sensor on my car and the code still won't clear. I've tried my crash sensor on another car and it doesn't produce a fault code on the other car.
I've tried 2 different airbag ecu's, (same part number) and both show the same fault code and it will not clear.
I can't see any break in the wiring from the crash sensor to the rest of the loom, but becuase there is damage to the alarm wiring in the same area, it must be damaged somewhere, which basically means it will be incurable without replacing the loom, which to do so would write the car off.
The alarm switch wiring may have been cut and joined because the bonnet switch stopped working.
If you're sure it's the wiring from the crash sensor causing the problem, just fit 2 new wires from the sensor to the ECU.
If you're sure it's the wiring from the crash sensor causing the problem, just fit 2 new wires from the sensor to the ECU.
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Twincam1986
New member
I've been told it won't be as easy as that, as the repair would be very hard to be precise enough to bring the resistance readings into tolerance for the ecu.
The only resistance issue is to ensure you make good 0Ω connections and seal them.
Special internal serrated, heatshrink crimp connectors will be available from a good auto electrician, and use the same specification wiring as already fitted.
Special internal serrated, heatshrink crimp connectors will be available from a good auto electrician, and use the same specification wiring as already fitted.
