Mode $0a on 7730

[D. Barry Stubbs]

Paul Blackmore wrote:
> 
> 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.

No, you didn't suggest it.  I think I got the 57 from the ALDLMON page,
but now I realize that the author of that page intended the full string
to be F4 57 01 00 XX, at least to enter Mode 1.  Why there's the extra
00 there, I don't know.  So the LEN byte should be $56 + message length,
not including the mode ID?

 
> 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...

Luckily, I don't have ABS or SRS in this vehicle, and its not new enough
to have a PCM or BCM.  That's why I was confused when initially we tried
to 'shut up' module $0F based on the chatter I recorded.

The first byte of the heartbeat (F0 55 BB) is the main ECM module ID?

> 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.

Alrighty, I'll give it a whirl later.
 
> 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.

I'm using (or attempting to use) the two-transistor circuit to do this,
but it does still echo... or at least PROBE says it does, as does
SCANTOOL 9 times out of ten.  What would a valid module response look
like?

> If the target module did not receive the command or the command was not
> valid then no response will be sent by the module.

I'm not getting any response that I can really determine, but maybe I'm
not 'holding my mouth right' as my granddad would say.

Paul, David, and Malcolm, thanks for all of your help.  Glad to know
someone's out there that doesn't mind their brain being picked to death
by someone who's in a steep learning curve.

========================================================================
D. Barry Stubbs                                    http://surf.to/z24man
(912) 745-9429                                     AOL IM: thez24man
z24man at earthlink.net          BNet Member #828     ICQ #5409648
#101DSP MidGa Region SoloII   94 Q4 5spd Aqua Z26  88 2.8 5Spd White Z24
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