PIC's and EST on a GM for traction control

[steve ravet]

Thomas Matthews wrote:
> What does the knock sensor
> output to the filter, and is it easily mimicked by a simple PIC? Any
> thoughts on how fast the ECM could respond to a faked knock signal?
> Or could I tap into the wires from the filter to the ECM and send
> the ECM a direct signal from the PIC?
> Any comments?
> Tom

The knock sensor in a GM is a piezoelectric microphone.  What it "hears"
goes to the EST module.  EST determines if there is knock present in the
signal it receives.  If it thinks there's knock, it signals the ECM, and
the ECM then retards the ignition.  I can't remember if the signal is
ground or +12, but it's all explained in the service book.

So you could send your retard signal to the ECM just like the EST module
does.  Don't know how appropriate that would be, as far as how fast the
ECM recovers timing when the knock signal goes away, etc.

--steve


--
Steve Ravet
International Meta Systems
http://www.imes.com
steve at imes.com