I have an 89 Iroc with the L98. It has the dual coolant fans. When I first start the car the primary fan runs for almost 30 secs and then turns off. It comes on and off normally then during regular driving. There is no SES light on, and I have looked for codes but found only code 12 which is normal. The engine runs fine but shakes slightly at idle but nothing bad. I replaced the CTS with a GM replacement and the wiring looks good. The car has 62K miles on it. Also the car has the ARAP prom in it with nothing else done with it except to reverse the fan turn on logic, but I dont think that would make a difference. It seems as though it is some sort of diagnostic for the fan??

 

Does your car have A.C.?
Do you have scan software that can tell you if the computer is commanding the fan to turn on?

I used ARAP code before, and it was backwards the way the fan worked. Off was on and vice versa. All I had to do was flag the N.O. fan control as you have already done, and everything was fine, at least as far as the fan was concerned.

Whatever is triggering the computer to think the fan needs to be on is what you have to find out. At start up the computer probably sees a need to have the fan on, so it turns it on, but the need goes away immediately, but the fan has a dwell time of about 30 seconds, so it stays on for a bit. The triggering factor is what you need to find. It could be something to do with A.C. or the temp sender. A diagnostic tool (scan tool) would be a great assett at this time. See if you can hook up with someone who has one.

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Karl Hunter
Hunter Motorsports
Vancouver, B.C. CANADA

 

The car does have AC but I do not have a scanner to tell what the computer is commanding!! What can I do?

 

I thought on an 89 car you DIDNT change the fan setting because it was correct. Its the 86-88 cars that have the opposite fan control.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
-=ICON Motorsports=-

 

The ARAP BIN does not have the Fan Switch set to Normal Operation as Karl mentioned. You have to set the Fan Switch to Normal Operation to make the ARAP work properly.

 

Well when I first put the ARAP in and the fan worked the opposite.....on when cold but off when hot. So I took it out and changed the switch in the code and it works correctly but the fan comes on for like 10secs when I first start the car!!!!!!

 

I can't answer the 10 second starting issue, as I primarily work on SD and I have never looked under my hood when first starting the car. I have to boot my scan tool AFTER I start my car, as my computer's battery is dead and when I crank the engine, no power flows through the DC/AC Power Invertor.

 

I think your fan turn-on at cold start up is normal. Mine does it as well. Did it with my stock GM chip, ADS chip, custom ARAP chip, etc... I just think there is some logic that runs the fan for a few seconds at start up, until it figures out that you don't need the fan on cuz the car is cold. I never really looked into it with my scan tool, just to see what is going on. Kind of took it for granted.

Glen, why are you using a power invertor to run your laptop? Just run a fused cig lighter power cord right into your laptop. It should take it. My CTX laptop uses a 9.6vdc battery, but the my regular AC adaptor puts out 21vdc to run the PC. Just thought I would let you in on my little tip.



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Best ET 14.413 @95.57 without
pulling valve covers or manifolds.
Also with stock 2.77 rear end!!!

 

Minor point...

N.O. is for Normally Open (versus normally closed), not for Nomal Operation. This is a basic electrical term relating to switches - the position they are in when not "energized".

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'87 IROC 5.7l TPI - original owner!

 

Because my Toshiba's battery is dead and I already had a charger and an DC/AC Power Inverter. Also, I occasionaly use a my Compaq notebook (it's batter isn't very good either). It uses a different type of charger and connector end from the Tosiba, so I must use the proper charger for that computer...but all work just fine with a Power Inverter driving them.

The Power Inverter plus into the cig lighter also.