Temp cooling fan should turn on?

Joined
Nov 14, 2005
What temp should the cooling fan turn on at?I seem to remember last year it was kicking on at around 150 but now this year its kicking on at 125 according to my scanmaster.Possiable bad temp sensor?If so which sensor is it?I know its one on the drivers side but cant remember if its the upper or lower one.
 
The chip controls when the fan turns on. What chip are you using? Do you know what the actual temperature is of the coolant? Do you have a temp gauge? If Scanmaster is showing 125* that is the temp the computer thinks the coolant is and the fan should not be coming on. Is the fan coming on in low speed or high speed? :confused:
 
Its a tt 5.6 chip.I dont have another gauge hooked up.I have the intrepid fans and its only wired to come on low speed,i use a toggle switch for high if its ever needed.So i guess the question would be why does the computer think its hotter than it is.I was thinking 1 sensor was for the comp and the other was for the fan to kick on.When i bought the car 3 years ago it had a blown engine and still the stock fan,after i rebuilt the engine and installed erics chip it was always coming on at 150.My stock fan stopped working and was replaced with a junkyard intrepid fan.Still turned on at 150.Now after parked for the winter it just starting coming on at 125 with no changes.I had tried switching the high and low relays and still no change.
 
86 GN Fan won't turn off

My mostly stock GN cooling fan sometimes won't turn off...even with the key off. Not every time, just every once and a while. I've only had the car about 4 days so I'm still exploring the engine bay but there has to be some kind of relay that's sticking or corroded in some way...or could be a temp sensor. I just need to know where they are. Anyone offer some insight?
 
The temp sensor is on the front left of the intake manifold.The relays are on the driver side inner fender.If sometimes it wont turn off its probably the delay relay(the biggest one).Unplug it if its running when it shouldnt be,if it stops that your problem.You can leave that relay unplugged and never worry about it again or replace it.Its job is to cool the engine down after the car is shut off for X amount of time.Its a very common problem and many people just leave it unplugged.
 
I hooked up a mechanical gauge and its close to the scanmaster temp reading.So where do i go from here?

Computer controls fans by activating the fan relay. Hopefully clear on this.

The "Chip" has programming when to kick fan on. So if Eric said 165 in the chip.. when the temp sender hits 165 the ECU send a signal to activate the relay. Hopefully clear on this.

The scanmaster displays what the computer see's. Clear ?

So if its 125 degree's on the CLT reading and the fan kicks on then either your chip is bad, computer is bad, or fan relay is being told to activate by something else. The sensor is doing its job as it reads temp. The scanmaster is doing its job of displaying what the sensor reads.

You can if you have a direct scan or power logger see the "Fan" flag kick on.


Turning on your AC can activate the cooling fan as well. Shutting of the car with the AC ON will run the fan to help cool it down. So make sure the AC switch is off while troubleshooting this.

HTH
 
I have talked with eric and he said to send him the whole ecm and he will plug it into his car and see what happens.He also said he has never heard of a chip failure to do this.But he will check it over.
 
Cool..

Check for corrossion on the 2 plugs on top of the ECM. Buicks are notorious for water rotting the ecu.. that can create havoc.
 
I will check that first.My first ecm had got water in it 2 years ago.I had since rapped it with plastic so it didnt happen again.
 
Ok so i sent the emc to eric and he plugged it into his car and it worked fine.So i got it back today and started to try to figure out what was going on.I did figure it out and it was my fault that it happened.First the high speed fan sensor reads wrong,second when i wired the intrepid fans in i ran the car and waited for the ecm to command the fans on(little did i know it was the high speed commanding in on early).So when i wired the fan i thought that was the low speed and wired the fan that way.And i guess the sensor must be getting worse causing it to come on even earlier than last year.And the orignal fan was wired to jump the resister so it always was on high speed.So yes i feel dumb but im glad i got it fixed now,thanks for all your help.
 
A suggestion...

My mostly stock GN cooling fan sometimes won't turn off...even with the key off. Not every time, just every once and a while. I've only had the car about 4 days so I'm still exploring the engine bay but there has to be some kind of relay that's sticking or corroded in some way...or could be a temp sensor. I just need to know where they are. Anyone offer some insight?

Start another thread on your problem.
Makes it easier for others to follow, and not confuse some with 2 different problems...:wink:
 
Been a while: Doesn't the single pole sw on the intake serve as an overtemp protection device? Turns the fans on by grounding. [Something like 230*???]
A "what if" scenario.. This sensor is failing, and has begun grounding at a lower temp than designed?? Or, is that kinda like being "just a little pregnant"??
 
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