Benching ecms

[T Hergen]

The question relates to an internal ecm function that someone else on the
list (Peter?) referred to.  Some GM ecms apparently can switch in a
different pullup on the temp sensor(s) to give better resolution over the
covered temperature range (almost like increasing the number of bits of
resolution in the A to D converter).  Or, I may have misinterpreted the
posts.

If the ecms you're testing can do this, the 5k pot for the CTS (hooked up
like a TPS) would probably confuse the ecm when it switched ranges.  Using
only two leads of the pot (wiper and one other) may work better.

I'll try to find the posts on the topic in the archives before I stick my
foot further down my throat. 

Tom

On Fri, 31 Jul 1998, Bruce Plecan wrote:

> From: T Hergen <thergen at svn.net>
> Subject: Re: Benching ecms
> 
> 
> >Does anyone know if the 165/808 or 730 ecms are the type that switch in a
> >different pullup on the CTS (maybe IAT as well)?  If this is the case, the
> >use of the 5k pot (one end tied to +5 and the other to gnd) may not be the
> >best choice for the CTS & IAT. Something that more closely resembles the
> >temp sensor operation may work better (pulldown to ground).  I can go into
> >more detail if it turns out it's relevant.
> 
> The temp sensors are two lead, straight resistive loads.  I have a 
> 470 ohm inline just so there is a min load.
> Cheers
> Bruce
> >
> >Thanks,
> >Tom
> >
> 
>