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I am using PuTTY (similar to HyperTerminal) and elm 327 (OBD Link LX) on my VW Polo 2015 model to read Airbag DTCs.

    Command sent: AT SH 715
    Received: OK
    Command sent: AT CRA 77F
    Received: OK
    Command sent: 19 02 08
    Received: 
77F037F1978 
77F037F1978 
77F037F1978 
77F037F1978 
77F037F1978 
77F037F1978
77F106B590299000002 
77F2189000007990000 
77F2208990000730900 
77F2300319900003299 
77F2400005299000050 
77F2599901712989000 
77F26119890001A9890 
77F2702119890021298 
77F2890021A98900712 
77F2998901C0199901C 
77F2A1298901C009890 
77F2B1D0199901D1298 
77F2C90160098A00600 
77F2D08C1550019C121 
77F2E0019C1670018C0 
77F2F010099AAAAAAAA

Can someone help me decode this raw data and find out the DTCs. Looks like there are a lot of faults in the car.

  • Why not just use a code reader which will also translate the codes for you. What you may have there is the readings over time... – Solar Mike Mar 6 '18 at 10:34
  • 1
    @SolarMike - While not stated in the question, I'd bet the OP is working their own solution. Looking at their previous questions confirms this ... This is actually a great question, as getting a solution to read SRS or ABS codes through the EML327 would be a GREAT addition as I've not seen any solution thus far which does it through this type of device. – Pᴀᴜʟsᴛᴇʀ2 Mar 6 '18 at 15:35
  • @Pᴀᴜʟsᴛᴇʀ2 I would not be prepared to accept that those are all faults - I « hacked » a 3.5 inch floppy to get the Hex code and used a program to decode it all ... decoding this means knowing the manufacturer’s lookup table etc... – Solar Mike Mar 6 '18 at 15:53
  • @SolarMike - I'm not suggesting they are all fault codes either, but it is output. If it is for the SRS or ABS, it would be a great leap forward for using the ELM327. You may be right these are readings over time. They might actually be codes. Hopefully someone can help decipher what's actually there and help the OP. This question directly reflects the OPs intent to continue working down the path of a self produced code reader which I'm all about helping along if I can. – Pᴀᴜʟsᴛᴇʀ2 Mar 6 '18 at 16:46
  • The ELM327 is garbage, not a representative of automotive diagnostics or tools. It's great that you want to develop yourself, but use a better device. These are worth EXACTLY what you pay for them, suspiciously little. ~an automotive electronics/diagnostics industry veteran. – Sam Basso Mar 6 '18 at 18:15
2

First let's define your query to the ECU:

19 - ReadDTCInfo
02 - Report DTC by Status Mask
08 - Status Mask

Ignore all this, it's only the module taking a moment to reply

77F 03 7F 19 78
77F 03 7F 19 78
77F 03 7F 19 78
77F 03 7F 19 78
77F 03 7F 19 78
77F 03 7F 19 78

This is a multi-frame message

77F 10 6B 59 02 99 00 00 02
77F 21 89 00 00 07 99 00 00
77F 22 08 99 00 00 73 09 00
77F 23 00 31 99 00 00 32 99
77F 24 00 00 52 99 00 00 50
77F 25 99 90 17 12 98 90 00
77F 26 11 98 90 00 1A 98 90
77F 27 02 11 98 90 02 12 98
77F 28 90 02 1A 98 90 07 12
77F 29 98 90 1C 01 99 90 1C
77F 2A 12 98 90 1C 00 98 90
77F 2B 1D 01 99 90 1D 12 98
77F 2C 90 16 00 98 A0 06 00
77F 2D 08 C1 55 00 19 C1 21
77F 2E 00 19 C1 67 00 18 C0
77F 2F 01 00 99 AA AA AA AA

You can view this message as

Command:

59 02 - ReadDTCInfo(19+40 = 59) Response > Subfunction 02 - Report DTC by Status Mask

Data: Status Mask | Format Id | DTC

99 00 00 02 - 99 | 00 | 0002
89 00 00 07 - 89 | 00 | 0007
99 00 00 08 - 99 | 00 | 0008
99 00 00 73 - 99 | 00 | 0073
09 00 00 31 - 09 | 00 | 0031
99 00 00 32 - 99 | 00 | 0032
99 00 00 52 - 99 | 00 | 0052
99 00 00 50 - 99 | 00 | 0050
99 90 17 12 - 99 | 90 | 1712
98 90 00 11 - 98 | 90 | 0011
98 90 00 1A - 98 | 90 | 001A
98 90 02 11 - 98 | 90 | 0211
98 90 02 12 - 98 | 90 | 0212
98 90 02 1A - 98 | 90 | 021A
98 90 07 12 - 98 | 90 | 0712
98 90 1C 01 - 98 | 90 | 1C01
99 90 1C 12 - 99 | 90 | 1C12
98 90 1C 00 - 98 | 90 | 1C00
98 90 1D 01 - 98 | 90 | 1D01
99 90 1D 12 - 99 | 90 | 1D12
98 90 16 00 - 98 | 90 | 1600
98 A0 06 00 - 98 | A0 | 0600
08 C1 55 00 - 08 | C1 | 5500
19 C1 21 00 - 19 | C1 | 2100
19 C1 67 00 - 19 | C1 | 6700
18 C0 01 00 - 18 | C0 | 0100
99 <---- I suspect the module doesn't support more than 0x6B size buffer or ELM327 messed up on this

This doesn't get you the full answer, I would confirm by using another tool to see what codes it can read from the airbag module and give you an idea what you are expecting.

You're going to need to find a way to use OE tool data and extract what DTC code means, in this case the OE tool is ODIS and you can get a subscription but it is expensive. On that same point I would recommend stop using an ELM327 and start using a J2534 device for development like this, the good thing about this would be that all OE tools must support J2534 devices.

  • Thanks for the answer. So according to you, the DTCs are 0002, 0007, 0008,..... I googled these codes (i.e. 0002, 0007) but didn't get fault code descriptions related to airbag. Even if I change it to P,B,C,U according to SAE format it comes out to be P0002, P0007, P0008... etc which are Powertrain codes and not Airbag codes. – Soumya Sen Mar 7 '18 at 10:45
  • Again the format may be incorrect. I would use an OE tool and see what error codes do exist and then figure out how to get those error codes out of the data returned. – Damon Earl Mar 7 '18 at 17:28
-1

77F 03 7F 19 78 this answer from airbag ecu means that "negative", need use other one response! ather digitals in answer is garbage.

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