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Alfa Romeo 145 - 146 Forum _ ECU Diagnostics _ ECU Diagnostics (DIY)

Posted by: se145 21st January 2019 10:08

QUOTE(shpuncik @ 20th January 2019 12:45) *
Have you tried to see what errors you get with driver's airbag disconnected? Is it the same as above?

1. No, it won't. Default state of airbag warning light is always ON with ignition ON, airbag ECU turns it OFF in case of no faults. So by disconnecting PPL-WHT wire light will stay ON and airbag ECU will have another error like "warning light in instrument cluster is open/short bla bla bla" or something similar. Same is with disconnected ECU - light stays ON.

2. Usually system expects around 2.2ohm resistance, you could use even 3.3ohm but some cars detect it as too high and trigger error so 2.2ohm is best bet. But you could safely try with 3.3ohm and see if ECU is fine with that.
Yes, resistors help identify whether it's wiring or connectors are faulty. You could disconnecto connector under steering wheel trim which goes into clock spring, put resistor there to see if error goes off, or instead of driver airbag.

3. If horn works it doesn't mean ribbon cable isn't damaged. To be sure use multimeter and test pin-by-pin from both sides

4. Doesn't look like faulty ECU. When they are faulty they throw you error code "01" with description like "eeprom or ECU faulty". Still got couple of them on the table waiting to be repaired.


Thanks shpuncik. So the plot thickens. I tried MES to see what error I got when the airbag was disconnected, and now get additional error "04 - Driver squib circuit" (see below image) - which you would expect - but this then rules out the DRV/PASS mixup on MES/ECU?, and suggests my "05 - Passenger squib circuit" error is indeed for the passenger side (even though I do not have one, and looks like wiring is not present for it?). This also suggests clock spring is ok. I have a 2.2ohm resistor on the way, but looks like this will not help.

I had a relook for wiring, in case I do have the passenger airbag circuit, because the attached wiring diagram indicates cars should have it? With reference to the wiring diagram I could only see the wiring for the 3 pin plug, and connector G380 with PPL-WHT and ORN-LTB to the instrument cluster and fusebox - which looks wrapped in black after connector G380.

I did spot a yellow sheathed cable under steering column going back to the towards the fusebox. Thinking this is continuation of above, where the wrapped black cable gets a yellow sheath - but if not could it be the passenger airbag circuit terminated with resistor at fusebox? Long shot I know, but attach a photo of my fuses - all look as they should - or something extra in there?

Really scratching my head on this, really appreciate your help.




 

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