Re: Mode $0a on 7730

["Paul Blackmore" <paul_blackmore@hotmail.com>]

Hi Barry,

It's just a long shot but I have run into trouble (no pun intended)trying to 
clear the Diagnostic Trouble Codes (DTC). I believe there are History Codes 
as well as DTC's and I'm not sure if the mode $0A command clears the history 
codes. Not even sure if the history codes cause the MIL to flash.

In the following I have used XX to indicate the checksum byte.

I don't think the F4 57 0A 00 XX command would work (did I suggest that? - 
if I did I'm sorry for misleading you).
You're best sticking with the F4 56 0A XX command.

I have also seen reference to DTCs in other modules - again not sure if they 
cause the MIL to flash - I would expect they do.
So you might like to try "clearing" the DTC's from those modules.
i.e.
if your BCM was ID $F1 then use $F1,$56,$0A,$XX
if your ABS was ID $F9 then use $F9,$56,$0A,$XX
if your SRS was ID $F2 then use $F2,$56,$0A,$XX
etc...

Lastly I have seen this mode $04 command used for clearing "stuff"
$F4,$57,$04,$40,$XX
I have no idea if it would work on your vehicle though.

If the target module receives and processes a valid request you should get a 
response from the module - but don't confuse the module's response with the 
max232 circuit's echo of the original command.
If the target module did not receive the command or the command was not 
valid then no response will be sent by the module.

Cheers
Paul Blackmore

--------------- Original Message -----------------
Date: Mon, 17 Jul 2000 14:42:31 -0400
From: "D. Barry Stubbs" <z24man@earthlink.net>
Subject: Re: Mode $0a on 7730

Sorry for the neglect.  I personally didn't add the checksum, but the
program itself (PROBE) did.   Aside from that, the rest looks OK?
Another thing I forgot to add is that, I've seen F4 57 OA and F4 56 0A,
depending on the source.  BUT, I did try both, with the appropriate
checksum, and neither cleared the malfunction codes.


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