reprogramming ECM?

[Jim]

Quick question
What is this service item? And do they actually do anything??? I thought I
once heard it's the equivalent of just disconnecting the battery for a
while?

2000 OBW if that matters....

Thanks!

 

[CompUser]

Quick question
What is this service item? And do they actually do anything??? I thought I
once heard it's the equivalent of just disconnecting the battery for a
while?

2000 OBW if that matters....

How do you mean 'service item'?

Disconnecting the battery for a while (or just
for seconds, and holding brake pedal down for
ten) will *reset* your ECU...basically cause it
to reboot, with all it's learned information
cleared.

 

[Jim]

I think reprogramming the ECU/ECM is part of the regular maintenance
schedule isn't it? That's what I mean. Is that all they do? Just reset it by
killing the power? Well actually, they must have some other way since the
clock and radio etc do not get reset when they do it, but it was all reset
when my battery died and it reset on it's own.


Thanks,
Jim

 

[Jim]

Actually, I just found this thread:
http://groups.google.ca/groups?hl=e...091946.04483.00001319%40ng-fv1.aol.com&rnum=3

Which pretty much answer my questions as long as the same applies to s 2000
OBW which I imagine it does....

Thanks,
Jim

 

[mulder]

Disconnecting the battery does not reprogram anything. It just clears
out the adaptive memory in the ECU so all the learned data is erased and
the learning process has to start over again for fuel mixture and timing
values. It also erases any stored trouble codes and resets the OBDII
readiness tests. However the basic "map" in the ECU which contains its
operating instructions does not change.
Occasionally Subaru may come out with updated firmware for a particular
vehicle/ECU for various reasons, to correct issues such as drivability
problems, emission parameters, falsely set trouble codes etc. The dealer
will then perform a "reflash" procedure to load this new code into the
ECU. That may be what your dealer was referring to.
There are also aftermarket companies that can perform a reflash to
improve performance, but this is generally done with the
high-performance vehicles such as the WRX and STi, and also done to
accomodate other modifications such as high-performance turbos and
exhausts.

 

[Jim]

OK. I do realize that. I guess my question is still what does that item in
the regular maintenance schedule refer to and is it equivalent to clearing
the ECU memory by killing the power?

Jim

 

[mulder]

I've never seen that as a regular item in scheduled maintenance. There
is no point to having it reset at a service anyway since the ECU is
constantly learning and adjusting timing and mixture according to its
knock and 02 readings. Resetting starts the process over from the
default settings but doesn't otherwise change anything.
Is this something in the maintenance schedule that came with your car in
the manual, or is it in the service "menu" provided by your dealer?

 

[CompUser]

I think reprogramming the ECU/ECM is part of the regular maintenance
schedule isn't it? That's what I mean. Is that all they do? Just reset it by
killing the power? Well actually, they must have some other way since the
clock and radio etc do not get reset when they do it, but it was all reset
when my battery died and it reset on it's own.

We might be dancing around the same bush, but
calling it a different name, here.

"Resetting" the ECU is essentially the same thing
as powering down your PC, and letting it reboot.
In our ECUs, they accumulate some "learning"
about how we drive, shift points etc, as well as
the quality of fuel that's being used, and other
things that I sure don't know ;-)---THAT info
will be purged, when the ECU is reset.

"Reprogramming" (to me, anyway) implies something
more substantial than a reset---making an actual
change to the base code that the ECU starts up
with, and works from ever after. In this sense,
reprogramming would be more like doing a Windows
Service Pack 2, on your XP machine. Most folks
would call this a "reflash", in terms of Subaru
ECUs. Also, during a reprogramming or reflash,
all the learned info would be purged, just as in
a reset.

As far as the clock & radio presets being ok, I'd
imagine both resetting or reprogramming/flashing
of the ECU could be accomplished without messing
with them. Or, they could take note of your FM
presets, and restore them afterwards. It's kind
of inconclusive.

HTH

 

[Jim]

OK. I've rechecked my service manual that came with my 2000 OBW. The 24000
kms service has an item "Reprogram Engine Control Management System". I
imagine in the US the same item is in the maintenance schedule every 15000
miles?

So my original question is...what is THAT?

Thanks,
Jim