[Gmecm] Ignition off fan

[Scott Peitzsch]

I did a poor job answering the question first time around.  The code does
support two fans, but the hardware does not.  The turbo Sunbird does
indeed have only one cooling fan as shown here:

ftp://ftp.diy-efi.org/pub/gmecm/manuals/1227749/749sunbird3.jpg

It runs in full speed mode when the ignition is on, and in slow speed
mode when its off to reduce current draw on the battery during the
fan run-on period.

-Scott

----- Original Message ----- 
From: "Robin Handley" <Robin at FuryWorld.fsnet.co.uk>
To: <gmecm at diy-efi.org>
Sent: Wednesday, June 28, 2006 4:38 AM
Subject: Re: [Gmecm] Ignition off fan


> Thanks Scott, although I'm confused. The $58 code has lookup values for 
> two
> fans, so I had assumed that the Sunbird and/or Sy/Ty had two fans. Am I
> wrong? Since I have proved that the high fan temperatures drive my fan, it
> would be weird if the low fan temperatures weren't used for something...
> What am I missing?
>
> Robin
>
> ----- Original Message -----
> From: "Scott Peitzsch" <jlg-sep at comcast.net>
> To: <gmecm at diy-efi.org>
> Sent: 28 June 2006 01:09
> Subject: Re: [Gmecm] Ignition off fan
>
>
>> Sadly, no.  The '749 ECM lacks quad driver U20, which would normally
>> have driven the Secondary Cooling Fan output at pin F8.  Its sister ECMs
>> (the '727 and '730) have this driver and the capability to run both fans.
>>
>> Since you're reworking code anyhow, or at least on your way, you might
>> consider redirecting the secondary fan output to another existing quad
>> driver
>> channel whose original function can be eliminated in your application.
>>
>> -Scott
>>
>> ----- Original Message -----
>> From: "Robin Handley" <Robin at FuryWorld.fsnet.co.uk>
>> To: <gmecm at diy-efi.org>
>> Sent: Tuesday, June 27, 2006 6:34 PM
>> Subject: Re: [Gmecm] Ignition off fan
>>
>>
>> > Thanks Scott. Both fans?
>> >
>> > Robin
>> >
>> > ----- Original Message -----
>> > From: "Scott Peitzsch" <jlg-sep at comcast.net>
>> > To: <gmecm at diy-efi.org>
>> > Sent: 27 June 2006 23:26
>> > Subject: Re: [Gmecm] Ignition off fan
>> >
>> >
>> >> > Anybody know if the Sunbird/$58 code supposed to keep the fan 
>> >> > running
>> > when
>> >> > you turn the ignition off? There seem to be calibration timing 
>> >> > values
>> >> > which
>> >> > suggest it... but mine goes off (mind you, it is wired as the hot
> fan,
>> > and
>> >> > that may be different. Trying to work my way through the fan code...
>> >>
>> >> Yes, there is code which will allow the fans to run-on after
> ignition-off
>> > if
>> >> the
>> >> coolant temp is above a threshold.  This feature is especially useful
> on
>> > the
>> >> turbo Sunbird when its been shut off immediately after a hard run on a
>> >> hot
>> >> day.
>> >>
>> >> -Scott