When I had my 1985 Camaro I swapped in 1991 wiring and ecm. I had 1991 dual fans and remember adding a pin to the ecm harness that ran to the fan relay and would activate it at specific temperature.

Can the 1987 165 ecm do the same? I hate to rely on the cylinder head switch/ac pressure switch to activate the fans.

 

The $32 and $6E firmware in the '7165 will only control one fan.

RBob.

 

I had Tunedperformance send me a memcal programmed with I believe a 1989 $6E. I will double check with him though.

By any chance do you know what ECM pinout would be used to control the fan relay? Is it already wired that way?

 

C1 iirc I set it lower , will look tonight

 

how the dual fan setup operates is still a bit of a mystery to me. there seems to be a few modes of operation, and decisions made by the computers

1. Engine cold, a/c off ===> all fans off
2. engine cold, a/c on ====> one fan on, forget which one, if I had to guess, pass side
3. engine warm, ac off =====> only one fan (driver), but at some point both will turn on???
4. engine warm, ac on ====> both fans on, 2nd fan comes on immediately when first turning ac on
5. engine warm, ac on, turn off ac, turn back on a/c - this is is particularly peculiar, there seems to be a delay before turning on 2nd fan again when a/c switched back on and it seems unpredictable, or maybe I'm just impatient.

did I miss anything??

maybe #5 has something do do with a/c pressure. but in #4, 2nd fan always seems to turn on right away

 

Settings lowered 200f on 185f off

 

I read through Willie's coolant fan specification and modification article. Is it correct in stating that the 1987 cars secondary cooling fan only comes on with the fan switch in the head and that the primary fan does NOT come on as soon as Air Conditioning is selected? The article says 1988-1992 cars will perform this action.

Brian, with your new tune based on a 1989, will the primary fan now activate with Air Conditioning? Is this theory of operation hardware or software based?

 

not sure about secondary fan control and ecm don’t have a schematic.
iirc the ecm has a/c request so that could bump idle and possibly control secondary with head switch .
if you jumper a to b at the aldl to test what fan is ecm controlled.
$6e does have fan setting with and without a/c request on/off temps.

 

I've giving my Formy some love right now, fired her up, turned on the a/c (engine cold) both fans turn on.

turn off a/c, drive side fan remains on for about 1 min, then turns off

turn back on, drive side back on, pass side off. about 1 min later, pass side turns on

ac off, temp now 110, turn back on, driver side on immediatly, pass side on in about 30 sec this time

ac off, temp now 120, turn back on, driver on immediately, pass side on in about 15 sec

ac off, let temp rise about 220, around 230, driver fan comes on. (seems too late to me in Austin) turn on a/c, pass fan turns on immediately

ac on, temp falls under 220, turn off a/c. pass fan off right away, drive side off in about 1 min

temp still under 220, a/c back on, both fans turn on immediately

done playing, now I remember why the 2 fan operation is a bit of a mystery