ALDL, again

[Ward Spoonemore]

I think this ia s C3 ECM and your looking at it as async data ?

The ECM your looking at has a 25 byte output starting with the 2 byte EPROM
ID, this is the scan ID
the catch is that the data is syncronous at 160 baud. This data string
requires no stimulation it just chatters on endlessly.

Calib APR/0164 HAS A SCAN ID OF 0042
Following the 2 ID bytes are some interesting flag bytes, and so on.

Coolant si the 4th byte, to conversion is:
	COOLANT TEMPERATURE,  Deg c = (n * 0.75) - 40
	(n = the decimal values of the binary output)

WARD.
-----Original Message-----
From: owner-diy_efi at efi332.eng.ohio-state.edu
[mailto:owner-diy_efi at efi332.eng.ohio-state.edu]On Behalf Of Roger
Heflin
Sent: Tuesday, March 02, 1999 6:21 PM
To: diy_efi at efi332.eng.ohio-state.edu
Subject: Re: ALDL, again




On Tue, 2 Mar 1999, Padgett 0sirius wrote:

> Well just a quick look at my Fiero (1227170/APR0164) ALDL (C3) gives a
> stream like this:
> 000 A4 00 2A 4D C5 00 38 3B 14 80 90 00 20 00 60 24
> 010 1A 87 90 01 4A 00 97 00 68 A0 00 2A 4B C5 00 37
> 020 34 14 80 8F 00 20 00 60 25 1A 88 90 01 4A 00 97
> 030 00 70 A0 00 2A 46 C5 00 36 33 14 80 8E 00 20 00
> 040 60 24 1A 88 90 01 4A 00 97 00 6E
> (then repeats for the next frame).
>
> 00 2a (42) is the reported PROM ID. Diacom software interprets as follows:
>
> Engine Speed................... 1275 RPM
> Vehicle Speed..................    0 MPH
> Coolant Temperature............  224 F
> Manifold Air Temperature.......  106 F
> Throttle Sensor Voltage........ 0.40 VDC
> MAP / Vacuum Sensor Voltage.... 1.08 VDC
> Oxygen Sensor Voltage..........  628 mV
> Oxygen Sensor Transitions......    1 #
> Battery Voltage................ 13.6 VDC
> Idle Air Position..............   70 #
> Injector Pulse Width...........  1.7 mS
> Spark Advance................... 26.1 DEG
> EGR Duty Cycle.................    0 %
> Integrator.....................  128 #
> Block Learn Multiplier.........  144 #
> Closed Loop Status.............  Off
> Fuel Mixture Status............ Rich
> Battery Status................. Norm
> Torque Converter Clutch........  Off
> Park/Neutral Switch............  Off
> Power Steering Switch..........  Off
> EGR Diagnostic Switch..........  Off
> Learn Control..................  Off
>
> Using available data, it seems likely that the "A0" at offset 019h (sorry,
> I find it easier to think in hex) is coolant temp (1.35*160-8), "33" at
> offset 039h is the RPM (1275/4=51/33h), & 46h at offset 035h is IAC (70).
> Suspect the rest can be decoded the same way once I get a chance to
compare
> several readings.
>
> Or is all of this common knowlege /way off ? Am trying to come back up to
> speed.

>From my experience, your conclusions are correct.  And knowing this,
with a few more frames you should be able to decode all of the info
displayed by diacom.   There is probably some additional info that is
in the data stream but not displayed by diacom.  There are quite a few
bits of info I found about, and decoded, that were in the raw diacom
file but not displayed by diacom.

				Roger