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john.jack
Novice
May 11, 2017, 6:22 PM
Post #1 of 12
(1805 views)
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My 1999 lesabre is overheating.
After you drive it 30 miles the radiator fans never come on. It is blowing water
out the hose connection next to the radiator cap now and it is being towed home. That
hose goes to the resevoir.
I put a new radiator on it today because the old one was cracked on the side
It has no temperature guage so I don't know if it is getting
hot enough to open the thermostat.
I checked fuse 5c and it is not blown
I pulled the temperature sensor wire off the sensor with the key on and the fans did not come on
I shorted the wires acrcoss each other after I pulled the wire off and the fan did not come on.
I will get two new relays and put them in tomorrow aand install a new thermostat I just bought
I am beginning to think I am missing something
What should I do
1)now to stop it from blowing the water out the hose and
2)how do I determine if the thermostat is opening and
3)how do I know if the fans are working properly if they don't
come on and I don't know if the motor is hot enough to get them to come on
(This post was edited by john.jack on May 11, 2017, 6:54 PM)
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Hammer Time
Ultimate Carjunky
/ Moderator
May 11, 2017, 7:55 PM
Post #2 of 12
(1793 views)
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Since you don't have a temp gauge, you are going to need a scan tool to look at the temp and status of the fan circuit.
Do the fans come on with the AC?
Have you tested for power and ground arriving at the fan motor?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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john.jack
Novice
May 12, 2017, 5:14 AM
Post #3 of 12
(1781 views)
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The fans do come on with the ac
I don't have a scan tool. I am not sure I understand what you are referring to.
I will check the fans with a volt meter to see if they are getting current then I will try to check the fans to see if they come on if I hook them up to current directly. Hopefully that will give you the information you need that a scan tool
would give you.
I have been looking at this for a day now. I have already learned that I need to determine if the temperature sensor
works and send a signal to the ecm to turn the relays on. They said if I unplug it should trigger the fans to
come on and to then short the two wires together on the sensor and the fan should come on again. It never came on.
Is what I have been told correct . If it is why am I not getting juice to the sensor. Is there a fuse to that
sensor that may be blown?? If so what is it called and where is it. I was told there is a number 4 fuse under the hood
that should be hot all the time. I can't find it so I don't know.
Unfortunately for me the only wiring diagram I could get was an autozone diagram. It is for a 1998 lesabre and shows that there is a black wire that is connected to the ecm and a yellow wire that is connected to the ecm.
the 1999 lesabre I have has three wires, It is hard to tell but they appear to be yellow or maybe white, black and and green . After I turn the key on when I test the black and the white with my voltmeter I get 4.9 volts. I know that is a signal the computer sends to sensors like the tps so I guess it is ok. It must be sending that signal to the temperature sensor to for some reason. The green wire shows zero volts.
I am thinking the green wire should be the hot wire but it is not getting any volts. I am thinking the temperature sensor is not getting the current it needs to determine how hot the motor is and not sending any signal to the ecm that tells it that the engine is hot and needs the fan to come on. Could this be the problem.
I think looking at the wiring diagram you sent me and I think it indicates that once the ecm gets as signal from the temperature that it must then tell the relays to turn the fans on.
I hope I have resonded with answers to the questions you asked. Once I started typing I could not remember all the questions you asked and I could not go back and read it again without losing my post. So, I may have missed something. I will reread it afterI make this post and if so i will answer any question i have missed. If I need to get a scan tool where do I get it and what should I call it?
I won't buy any new relays until you get back with me. I'm thinking if they come
on with the ac then the relays may be ok.
I figure you will be able to tell me what the problem is today. I will go ahead and put the thermostat in. I've already bought it and the old one is old enough to replace anyway. I figure since the water got hot it must have been opening and circulating hot water to the radiator. I burned my hands when I pulled the hoses anyway. Crazy thing is
my wife told me when she saw the water coming out of the resevoir hose she turned the ac off. I guess the fans
had to have been running and it still got hot. I'm not an expert you are maybe you can tell what was probably
going on.
(This post was edited by john.jack on May 12, 2017, 5:24 AM)
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Hammer Time
Ultimate Carjunky
/ Moderator
May 12, 2017, 5:22 AM
Post #4 of 12
(1773 views)
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No no. Slow down here. You don't understand this circuit at all and you are going end up frying a computer. There are no fuses or power to the temp sensor. This same sensor inputs temp to the computer for fuel mixture and many other things. That is why you need a scan too to read the temp the computer is seeing.
If you don't completely understand electrical circuits and know how to read a wiring diagram, then you need to stay away from this and let a professional do it.
This is a fairly complicated, 2 speed circit for this fan that is controlled by the computer.
I gave you the wiring diagram already but if you don't understand it, then leave it alone before you do a lot more damage.
If you want to do something, use a test light and test all of your fuses with the key on.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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john.jack
Novice
May 12, 2017, 5:58 AM
Post #5 of 12
(1762 views)
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ok, At least I now know the fans come on if I turn on the ac. I have no clue how lone they stay on but at
least the relay that turns them on is ok. There are two relays one is low speed and the other is high speed.
I guess is it possible one of them is still bad.
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Hammer Time
Ultimate Carjunky
/ Moderator
May 12, 2017, 6:21 AM
Post #6 of 12
(1754 views)
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Wait a minute............ if your fans come on when the AC then you don't have a problem at all. Do they?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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john.jack
Novice
May 12, 2017, 7:11 AM
Post #7 of 12
(1748 views)
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Yes they come on with the ac.
I realized that and I wondered why it got hot because she had the ac on. i assume
the fans were running but I don't know if they run all the time or not if the fan is one.
Bother were running when after I turned the ac on.
I see know there is a air vent bleeder on the waterpump housing. I did not bleed it
the guy at the radiator shop said it did no have one and I should just run it
about 5-10 minutes with the cap off to get the air pocket out. I did not pull the
cover off the engine when I filled the tank and I could not see the thermostat housing.
I am thinking now that the buick had an air pocket in it and that is what made
it over heat. I had that happen with my son's 93 firebird once. When I worked
on cars they did not have to have the air pocket bled off. I'm old.
I've let it set running out in the drive for about 20 minutes and the fans still have
not come on. I will take it to a mechanic and let him look at it with a scan tool
since you said that is what needed to be done. I'll let him put the new thermostat
in it too since I have already bought it. I wish that thing had a temperature guage
on it but it doesn't. I assume it has a light but I don't know I've never seen it
get hot when I was driving it.
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Hammer Time
Ultimate Carjunky
/ Moderator
May 12, 2017, 7:15 AM
Post #8 of 12
(1742 views)
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One thing you have to understand is this engine is designed to run hotter at idle. The fans aren't even programmed to come on until about 226 degrees which many people think is a problem but it is not. It is intentional.
You may be right about the air pocket. That is a very common issue and will cause overheating.
Again, having a scan tool will allow you to see the temp the computer is seeing and whether or not the fans are being requested.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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john.jack
Novice
May 12, 2017, 7:50 AM
Post #9 of 12
(1732 views)
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They should have made it possible to check the temperature sensor to see if it was the problem easier.
I sure thought I have found the problem when the wire I thought was supposed to be hot was not.
I wish I had a wiring diagram to tell me what that third wire is and where it comes from. I know one wire
is the 5 volt reference wire and the black wire is ground but without the wiring diagram I can't dfetermine
what the third wird is
. My old truck only has two wires and when they slip off the temperature sensor which is often and
touch the manifold and get ground the guage peggs out. It has only two wires. The 99 buick has 3 and the 98
has two. On the 98 there is a grouind and the other goes back to the computer according to the autozone
wiring diagram.
I am sure the mechanic can help me fix it. I'll let him put the thermostat in so he will make enough money to
make looking at it worth while to him. He may just tell me to drive it if he can't figure out how to determine if
when the motor gets hot enough the fans will come on. I took a temperature guage and pressed it against the
hose and that didn't work. Maybe the scanner will do the trick like you say.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
May 12, 2017, 8:25 AM
Post #10 of 12
(1729 views)
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Just a note - one thing and out of this thread. If no gauge for temp it has a warning light. That light will light up with either key just on "run" but not running or during the seconds the starter is cranking as a bulb check that it works and bet it doesn't. It's boring and nobody does it but look inside the owner's manual what it should say or an icon but should be a RED color when on,
T
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john.jack
Novice
May 12, 2017, 8:42 AM
Post #11 of 12
(1720 views)
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Thanks Tom. My buick temp light does come on when you start it up.
Maybe this will keep me from getting the motor too hot if the fan does not come on when it should
I will ask the wife if the light came on when it started blowing all the water out through the resevoir hose.
She probably will say "I don know" .
I did check into it futher. The sensor has a 5 volt signal wire hooked to it that comes from the computere. The other wire is used to measure resistence those volts experience going back to the ecm . I assume the 5 volts is what the computer basis the resistence reflected by the compute when it measures the other wire that comes from the sensor to the ecm. Then it correlates that resistence to a table of measurement it uses to measure how hot the motor is. Once hot enough the ecm has the fan relays come on.
The resistence can be measured byswitch to the ohm meter measurement on my voltage meter and it should go up and down depending on how hot the sensor is or the sensor is bad. Then things get really confusing as to deterinine what
the ecm gets back on the wire. I assume it is volts going through from the signal wire back to the ecm.
Like Hammertime says there is not 12 volts going to the sensor. The sensor will cause the resisence to change in accordance to hot the sensor gets in the motor. At least now I can understand what the mechanic will be talking about.
I jsut hope he has a scanner and knows how to read it. This is my first rodeo and I hope it's not his first rodeo too. I sure don't want to take it to the dealer
You guys can close this I understand enough to know I need to take it to a mechanic with the right equipemnt to check it out.
I dropped by and the mechanic & he said he had no scanner like Hammertime said I needed. He said the dealer might but he didn't. He said just drive it until the light comes on. I did and after I drove it about 10 miles, parked and let it set the fans came on. Problem solved. I need to make sure the fan would come on as I was going to be driving through bumper to bumperr dallas cowboy traffic with my two grand kids in the back seat. I had to pic my wife up. Thanks for your advice
(This post was edited by john.jack on May 12, 2017, 5:29 PM)
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Hammer Time
Ultimate Carjunky
/ Moderator
May 12, 2017, 12:00 PM
Post #12 of 12
(1695 views)
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OK, apparently you are just not listening to what I am telling you.
As I said earlier I don't believe you have any problem with the fan, the sensor or the circuit but you insist on screwing with the sensor circuit. That can be easily confirmed by reading the sensor data on the scan tool.
If you really had an open or short in the CTS circuit, you would have a check engine light and a code set for that. The engine would be running like crap also.
It has 3 wires because one is for the temp gauge and 2 go to the computer for temp sensor reading for the computer.
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