L98 cooling fan problems

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Apr 22, 2003 | 11:29 PM

bstock72

Thread Starter

2nd Gear

Joined: Apr 2003

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From: DeSoto MO

L98 cooling fan problems

Ok i'm new here and have just stumbled along these forums have tried to read and see if i could figure this out but didn't see it anywhere so here it goes.
I have a 1991 L98 corvette and the fan doesn't turn on my engine temp. secondary fan comes on with the ac and when my friend hooks up his snap on scanner he can activate both fans so he say the fans and relays are good. I have replaced the sensor in the front of the intake and the fan still doesn't come on. does anyone have any ideas as to where my problem is? please help summer is on its and i'm already running hot.
:confused:

Apr 22, 2003 | 11:32 PM

CorvetteZ51Racer

Drifting

Joined: Dec 2002

Posts: 1,861

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From: Houston TX

Re: L98 cooling fan problems (bstock72)

Check the condition of the wire between the sensor and the relay. You're obviously getting the signal from the ECM to the fan, so the ECM must not be getting the signal from the sensor, and since the sensor's new, the wiring is the only thing left that I can think of.

Apr 23, 2003 | 09:34 AM

65Z01

Team Owner

Joined: Dec 2000

Posts: 90,675

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From: SE NY

Cruise-In II Veteran

Re: L98 cooling fan problems (bstock72)

Use the scan tool to determine what coolant temp the ECM is seeing; perhaps coolant temp isn't high enough to trigger the fans.

Are you running a low temp stat?

Apr 23, 2003 | 12:17 PM

Steel Blue 91

Le Mans Master

Joined: Jul 2002

Posts: 5,818

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From: Alive and well in Burlington NC

Re: L98 cooling fan problems (bstock72)

What temps are you seeing? The stock set up won't turn the fan on 'till ~230 degrees.

Apr 23, 2003 | 10:11 PM

ONEBAD89

Instructor

Joined: Apr 2002

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From: Delanson NY

Re: L98 cooling fan problems (bstock72)

I believe, at least on my 89 L98 the sensor in the front of the intake manifold controls the amount of fuel at start-up or something to do with that. You should have two sensors one on each side in each of the heads. Passenger side for temperature display and driver side controls the primary fan on/off. check em out!
Good luck
FRED

Apr 23, 2003 | 11:27 PM

bstock72

Thread Starter

2nd Gear

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From: DeSoto MO

Re: L98 cooling fan problems (Steel Blue 91)

scan tool will turn the fans on and is reading the same temp as the guage. And the guage will hit around 250 or so sitting at an idle and then the secondary fan will kick on

Apr 23, 2003 | 11:42 PM

VetteNoob

Le Mans Master

Joined: Jan 2002

Posts: 5,320

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From: Kyle TX (Because Mojo Made me fill it in)

Re: L98 cooling fan problems (bstock72)

Your ECM controls what temp the main fan comes on. The temp sensor on tells the ECM what the coolant temp is. If I remember correctly, I believe we actually have 2 coolant temp sensors. One is for the instrument gauge and the other is for the ECM. If I also remember correctly, the one for the ECM is in the passenger head. I'll check my manual and reply back if I need to correct myself.

Edit: Just re-read your last post about both scanner and gauge temps.

[Modified by VetteNoob, 10:44 PM 4/23/2003]

Apr 24, 2003 | 01:57 AM

SUPERNINJAB0Y

Instructor

Joined: Apr 2003

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From: santa maria ca

Re: L98 cooling fan problems (VetteNoob)

im in the same boat myself...well not entirely,i wired a manual switch which acutall sucks and looks like i have a nitrous botton!not by choice but becaue my fan didnt' come on a month agao. i relplaced my relay yesterday,and need to recrimp my wires and put in my jet lowtemp switch which is located in the passenger side head.i need time thats all,but using my botton sucks! its not a get in and go car anymore.have to worry about it failing and stuff.like it does.well see what happens tommarow.