1999 vw polo air bag ecu cant program

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1999 vw polo air bag ecu cant program

Postby spender4 » Fri Nov 25, 2016 1:29 am

VW Polo SRS CAN communication fault
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brittany polo can srs connected.psdata
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brittany polo can srs connected.psdata
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spender4
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Re: 1999 vw polo air bag ecu cant program

Postby STC » Fri Nov 25, 2016 10:47 am

Mr Spender

Very little information in your post to get a real and accurate understanding of your fault / symptom / problem.

However, your Can Captures Look ok to me, by adding a couple of Math Channels I can see that they continually add up to 5v recessive and dominant, and the 2v differential when in dominant state is being achieved.

Have Power Supplies been Load and Drop Tested ?
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Re: 1999 vw polo air bag ecu cant program

Postby spender4 » Fri Nov 25, 2016 11:18 am

Sorry that there was little information sent. every time I tried to post it would kick me out for some reason. The original SRS ECU had an EEPROM error fault code I can't remember the number, however after replacement there was no communication with the new ECU. there is also a communication fault in the engine ECU for instrument communication.
when looking at the CAN patterns while it may look normal on one page, on other pages of patterns there is following waveforms instead of opposing wave forms. the patterns are different when you have the SRS ecu connected to when it is not. I am unable to even see the SRS ecu with any form of scan tool including the ROSSTECH VAGCOM. have checked voltage and earth both loaded un unloaded to the SRS ecu and have found to be OK. not sure when I upload an image of the waveform whether it gives only one page or the wave form or all pages saved.
thank you for responding so quickly and hopefully you can sees the other pages of the waveform.
I have attached the non SRS ecu connected waveform saved
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brittany polo can.psdata
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Re: 1999 vw polo air bag ecu cant program

Postby STC » Fri Nov 25, 2016 8:07 pm

Ok, my mistake. I only looked at the one page.

Yes I can see the CAN being good one minute and then corrupted the next.

From what I have understood is that you had Communication with the original SRS ECU and you were able to communicate and read a fault code from it "EEPROM error"
With the old one fitted, Scope connected to Can hi & lo, Do you get a good or bad CAN ? Wiggle the cables ..... Can you make it go bad ?

however after replacement there was no communication with the new ECU.

Please Define "New" ?
Where did you get the replacement from ?
Is it the EXACT SAME part number ?

Using your VCDS (Vagcom) Can you post 3 Full Scans.
1. With Original SRS ECU Fitted - Please Clear all fault codes first, then scan with only Fresh Fault Codes & Data

2. With SRS ECU Removed - Again, Please Clear all fault codes first, then scan with only Fresh Fault Codes & Data

3 With "New" SRS ECU Fitted - It will need to bolted down, wont work unless it is grounded, Once again, Please Clear all fault codes first, then scan with only Fresh Fault Codes & Data.
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Re: 1999 vw polo air bag ecu cant program

Postby victor2k » Fri Nov 25, 2016 9:08 pm

Hello,
You can try to talk with SRS unit using VCDS on the table.Maybe your new SRS is faulty or isn't a proper replacement for your unit. :)
Please add more details about your car/SRS unit/fault memory.
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