new cooling sensor but still no fans

I just replaced my cooling temp sensor in the block but I'm still not getting my fans turned on.I'm going to replace the relays.

Before I go and change the relays I have a question.

Do you have to reset the PCM after replacing the cooling temp sensor or is it an automatic thing it recognizes?

You could say it's 'plug & play', nothing has to be reset. Do the fans come on when the air conditioning is turned on?

Yes they do but they turn off as soon as I turn the A/C off or change it to outside air.

Hi cougar.

Did you try my suggestions from the other thread.

I've attached the schema from a 2001 I think with the path for slow speed in red. Both fans are in series.

High speed applies full voltage trough relays 2 and 3.

All relays are required for high speed and I think you said you had fans but with the AC. I was not sure if that meant that both fans came on with the AC?

Pfofit I couldn't read any kind of wiring diagram if my life depended on it.They are too confusing to me to understand.

As I was driving down the road to go pick up my wife from work the idiot light came on again and the temp gauge went up plus this time the "Service Engine Soon" light came on so I stopped at a Autozone and had it checked.

It pulled two codes.One was P0401 for my EGR valve.The other one was P0118 for the coolant temp cIrcuit so I replaced the main(black)fan relay which was what they told me.

The fans are still not coming on and this is REALLY REALLY beginning to piss me off.I do not have all kinds of money to throw at this damn thing hoping the next part will fix the problem.

Nor do I have the electrical expertise to hunt this down myself.And I DEFENATLY don't have the money to bring it to a mechanic thats gonna charge me 75 bucks an hour to tell me it was one little wire.

So as you can see I am very frustrated at this point and also broke and can't have someone else do it for me so that leaves me with having to learn electrical systems in a hurry and do it myself.

So as they say."If it wasn't for bad luck I'd have no luck at all"

P:S yes both fans come on with the A/C and no I'm not screaming at anyone I'm just ticked off at my car.Another thing I did was swap out all the relays for the main ignition relay to test them.once i pulled them the car died so I know the other two(gray)relays are good.The only other thing I can think of is the wire harness that goes to the cooling temp sensor.

You say the temp guage went up--- so how high? Fans typically don't come on until engine temp hit 227 degf-- so just sitting idling- you will wait maybe 20-30 minutes to get the fans to come on--- How do you know you have a fan problem? You say they work with a/c- so there is no fan relay or fan motor problem. You may not even have a problem at all. You maybe just don't understand your system. If temp guage goes in the red and coolant is spewing out the overflow, then I'll agree, you have a problem--- but if temp guage goes up a little higher than "normal" then you probably are not used to seeing the guage reading with no a/c on during the summer months. You went all winter with guage at 3/8 now that it is summer and you are not using the a/c the guage reads 1/2---THAT IS NO BIG DEAL- and is considered normal. system is operating as it should. So what makes you think you have a problem?

What makes me think I have a problem is the water light on my dash keeps blinking at me telling me I'm getting too hot. Normally I would agree with you on the heating up to the half mark BUT when I got this car the temp needle NEVER went any higher than 1/4.

And never had a smell of over heating rad fluid like I do now.I am familiar with my car enough to know something is wrong.My temp gauge goes up to the half way mark and my fans kick on.Now they are not doing that so Yes something is not right.

I don't have to be the worlds best mechanic to know my car isn't acting right.I drive it everyday.I will be the first to know.You say the system is operating as it should?

My fans are not coming on AT ALL when she gets hot.You think that's normal?Is it normal to have to turn my A/C on to get the fans to move?

The only thing I can think of now is a connection problem in the harnesses somewhere.

That's annoying and unfortunate.

Where to start.
The "main black relay" is not the main relay. There is no main relay.

P0118 indicates and high signal coming from the sensor. This could mean the sensor is open/defective or there is an open/broken wire, bad connection somewhere between it and where it is going. Or the Pcm doesn't see the signal cause that input is toast(rare but possible.)

the Fact that you unplugged it and it worked for a bit is a good indication a bad connection/ broken wire at this plug. You need to look closely at this plug for corrosion at the pins and try holding the plug and pull slightly on each wire one at a time. If the wire insulation stretches then the metal wire inside is broken and will have to be repaired. Look along the length of the wire for scuffs breaks cuts or burn through s.

Wire diagrams. I don't know if it will help but here goes.
Look at the wiring diagram i posted and/or print it out to take with you to the car.
the relay on the left side of the page says "cooling fan relay #1".

That one HAS to come in for slow speed operation.
Which is what the car tries first to cool the engine down. If that dose not cool it down then the PCM will ask for the high speed but the temp gauge is most likely up to the 3/4 way by then.

How to read a diagram... I hope
From the lower left corner of the diagram, the pcm, through magic, will ground pin #6 which is a DK GRN( dark green) wire and goes to the relay coil at pin A3 at the underhood fuse junction box.

When the relay is powered it will move the contact within the box(note the dashed line from the coil to the contact) in the diagram, making that connection. If you follow my red line that is the path that connects the 12 volts through the contact and to the two fans in series (one after the other) to ground. There is a total of 12 volts so each fan gets 6 volts and they turn slower than if they had 12 volts.

Each time the wire goes through a differnet harness/plug there is a alphanumeric designation and color code to identify which is which in those plugs. There is also numbers associated with each wire that tell other info
For example: The A3 wire(middle left of diagram) at the coil of fan#1 has 0.35 DK GRN 335.

You already know the color code, the 0.35(probably mm) is the wire size and the 335 is the circuit number GM assigns to that wire, so that if your at another diagram you look for 335 to find the circuit your working on. Simple eh. right

Other info regarding plug numbers. If you look at just above where the fan motors are, you will see a dashed horizontal line with the letters A,B,C etc with a little double arrow head. The arrow heads indicate a plug and over to the far right of the dashed line is a designation C175 . C175 is that plug number and the ABC stuff are the pins in that plug.

At the bottom in the PCM box you can see C1 BLU, C2 clear. This indicates that the PCM has two connectors plugged into it one is C1 and is blue and the other is C2 and is a clear color.

That's the basic layout of most any wiring dagram. the trick is to follow the wire your interested in and try to ignore everything else until you need it.

To keep the fans on

Pull relay #1 from the car, turn it over and you'll see numbers by each of the fourpins. 30 and 87 are for the contact in the relay and the ones you want, they are in opposite corners.

The other opposite corners are for the relay coil which is powered through the PCM when it feels like it. You should see this in pictorial form on the side of the relay.
Get yourself a short wire. at least a few inches and stick it in where those pins(30 and 87) of the relay would have gone(use a wire as big as will stick in pins) . You need to be carefull as you look at the relay from the bottom and it flips when you plug it in.

If you do this, the fans should come on at low speed and then you can ignore the realys and go back to the sensor like the code P0118 points.

Of coarse the fans will stay on until you remove the jumper or your battery dies.

Cheers and good luck

I've added the same diagram but with the high speed activated with blue lines

Cougar . i just had another thought.

I do not know what scanner was used, but you had unplugged the sensor and that would have put the code into memory.

Do you know if the P0118 code was an active code or was it from the memory?

Did buddy erase the codes and do you have the money light on now? Check engne light, that is .

I'm sorry pfofit.Your doing your best with me but that was still German..lol.

I understand what your trying to say as a whole though.Doing that and killing my batt isn't an option.

The only other way I know of to keep the fans running is to disconnect the wire going to the coolant temp sensor in the block.That keeps both fans spinning at high speed as long as the car is running and they shut off with the car so that would be a better option.

I could be like others and do that and say the hell with it, my fans are working, but I'm one of those guys that likes to fix problems,not hide them.

As far as the p0118 code I believe it was an active code because it didn't throw that code until after I replaced the sensor and had the car running for a bit.Funny thing is I had NO codes for the cooling system until AFTER I replaced the cooling temp sensor.

I have a question for ya pfofit.That damn idiot light on my dash is indicating I'm overheating but it also tells you your low on radiator fluid correct?

If my low rad fluid sensor is bad will that cause these problems I'm having with the high temps?

I'm assuming no because if the low coolant sensor was telling the pcm I'm low on fluid wouldn't that command the fans to turn on to keep the temps as low as possible?

Or is the pcm so dependent on these sensors even one being bad will screw up the whole system?

Oh I almost forgot.No the "Service Engine Soon" light is now off.I think that went on because of the EGR code.When I started the car I guess the EGR unstuck itself and that light went off.The scanner used was an OBD II.As far as model and specs I have no idea.

Cougar,
Not knowing what the extent of your experience is, here it goes:

ANY air in the radiator will cause the low coolant light to turn on. If this is the case; standing at the front of your car - hood up - on the top left side of your radiator, is a screw. This scew is to bleed the air out.

Take this as you will. It's just one little hint, in your world of Intrigue problems. Good luck to you!!!

..ANY air in the radiator will cause the low coolant light to turn on. If this is the case; standing at the front of your car - hood up - on the top left side of your radiator, is a screw. This scew is to bleed the air out.
Normally, the low coolant sensor is located in the overflow reservoir and when no fluid is in contact with it the light comes on. Sometimes if enough crud is covering the sensor then it will read low. One has to remove the reservoir and blast a bunch of water in there to slosh it around and clean it out.

..
The only other way I know of to keep the fans running is to disconnect the wire going to the coolant temp sensor in the block.That keeps both fans spinning at high speed as long as the car is running and they shut off with the car so that would be a better option.......Unplugging the ECT sensor tells the PCM that it doesn't know the engine temp and turns on the fans, just in case. I can't remember if it's instant or takes a few minutes to power the fans after unplugging.

As far as the p0118 code I believe it was an active code because it didn't throw that code until after I replaced the sensor and had the car running for a bit.Funny thing is I had NO codes for the cooling system until AFTER I replaced the cooling temp sensor.Then that would indicate to me that the original sensor was fine and the new one or its installation is suspect. A missing or out of range signal will set an appropriate code and turn on the check engine light.

I have a question for ya pfofit.That damn idiot light on my dash is indicating I'm overheating but it also tells you your low on radiator fluid correct?I was only aware that it indicated low coolant. It's' red and a warning to get your immediate attention. The temp gauge tells you the engine is overheating.

If my low rad fluid sensor is bad will that cause these problems I'm having with the high temps?I don't know about that. Anything is possible within the magic of the PCM.

I'm confused about what is happening to you now.

Which lights are on and where is the temp gauge pointing/indicating at idle and when on the highway?
What is the ambient temp?
Where is the coolant level in the reservoir?

The fans will not come on until the gauge is up there like around the three quarter mark. Or unless you hit the AC and the refrigerants pressures, engine temp, rpms and vehicle speed are in the "range". Gms have different set patterns for when and what fans come on. I can't remember exactly the intrigues specs.

AT this point I'm not sure if you have a fan problem an ECT problem a gauge problem or a cooling issue like blocked rad, stuck thermostat, worn out blades on the pump, air lock around the ECT sensor or t-stat etc. Ya'll don't have a dead cat stuck to the front of the rad or something else blocking air flow and is your stupid air dam still in place?

I would stick an infra red heat gun at the t-stat housing to see the temp that the t-stat is releasing at(195) and then compare that to the dash gauge setting for accuracy. I believe 215-220 is around the 3/4 mark.But I've been wrong before , many times. Assume nothing. Or a a probe thermostat stuck in the center dash vent to measure heat at hot setting is another way to determine the temp of the coolant taking account for some losses from the heat transfer. F'instance, if the temp from the vent is 220 then it's heating up and the fans should be doing something . If it's 170-180, then your fine.

If the low coolant light is on, then clean out the reservoir.

For what its worth, I have seen the low coolant light come on a time or two, but Ive never seen it blink, not even the couple times when my temp gauge pegged out when I had some thermostat issues...my car was so hot the fans were running with the engine off...thats hot, and I dont remember ever seeing a light.

I agree that you could have air in the system, especially if youve had any cooling system work done recently. Also I assume youve checked the coolant level. These two things go together because if theres air in the system, the coolant level can appear to be correct, but its actually not.

Just below the half mark is where these cars normally seem to run, maybe even with the half if youve been sitting in traffic for a while. I would say the 1/4 mark is cold, but your gauge or sensor could be off. If its smelling hot and stuff dont doubt your instincts.

Also until you do get it fixed, Id say do whatever it takes to keep your temps where they need to be, this time of year most people are running AC all the time, so you shouldnt be getting hot. You could also wire up your own relay to the fans and signal the relay with a switch inside the car, wouldnt be terribly hard.

The reason I suggest doing whatever is necessary is that aluminum engines arent known for being able to withstand much overheating. But then again, I dont actually know what engine you have, the 3.8 engine will tolerate it much better than the 3.5.

You should add your car info to your signature, it makes it easy for people here to know what you have.

You really need a scan tool so you can see what temperature the PCM is reading from the CTS (coolant temperature sensor).

The coolant temperature sensor should have 177 ohms of resistance @ 212 degrees. If you have access to a voltmeter then you can place the lower portion of the sensor in a pan of boiling water & measure the resistance. You could also purchase a 177 ohm resistor(s) at Radio Shack & connect it in place of the CTS. With the engine running & this resistor in place the fans should come on & you can check were the dash gauge reads 212 degrees.

Well I'll be an idiot.I didn't even think of that.Air in the system is a possibility because I did flush the system after I got it because there was ALLOT of crude in the rad.

Not saying that is the problem but couldn't hurt to check it.And the coolant low sensor is mounted on the left top side of my radiator next to the battery.At least I think that's it.lol

The overflow tank I keep almost 3/4 full because the way they mounted it in there I can't see the "full hot" and "full cold" level lines so I have to guess.If your right pfofit and the low coolant sensor is in the overflow tank then I have no idea what the sensor is mounted to the left side of the rad.

Not saying I can't find out.I do have Alldata.Just have to check it to see.But in the meantime I have disconnected the coolant temp sensor in the block so the fans will come on.

As far as temps go all I can tell you(without using a probe)is my temp gauge(when acting normal)goes a tidbit higher than the 1/4 mark when the temp is normal and doesn't move from that spot.

Now with this fan problem my temp gauge is going a tad bit higher than the half mark and I'm getting the hot coolant smell.The idiot light on the dash blinks at me every 1/3 seconds.

I have begun to notice the idiot light will blink at me even just after I start the car and she isn't even hot yet so that MAY be due to the low coolant sensor being bad or cruddy.

Yesterday I cut out the harness clip that goes to the coolant temp sensor in the block and wired it directly just to see if that clip was bad but it did nothing so it wasn't that.

I will go ahead and fight to get the overflow tank out and see if the coolant level sensor is indeed in there and clean the little bugger out and see what happens.

And to answer your question my temps here in North Caroline are in the mid 80's and higher.Allot of 90's day so far and gonna get hotter soon.But I this problem starter when i left for my vacation to go up north and the temps in Mass where only 70's so I shouldn't have been getting hot enough for the gauge to read at the half way mark.

Okie dokey, i see you have the 3800 and all this time, i thought we were playing with a 3.5. :frown:

Well now, what I've said before re diagrams, lights and pcm behavior et al is probably irrelevant for you.

What light is the "idiot light" that you refer to? What is it called in the user manual and what does it say about this light in there?

It is important to keep the level in the reservoir in the correct zone. If it's too low air can be sucked in to the system and to high will cause pressure build ups that will make it hard for air to get out, not to mention overflowing.

Find out where the levels are and make new marks with a black sharpie or whatever so that it is visible to you without a big todo.

Since you have flushed the system, there may well be air in the system. Quite common. The easiest way I use is to first loosen the cap(be careful if the car is already hot) just enough to let out a hiss, then get the coolant in the reservoir to the low level. Start er up, wait a bit and keep nudging the cap loose to let pressure hiss out. Then drive around like this for a few minutes and loosen the cap again until it hisses again. Keep rinsing and repeating until the pressure is allowed to bleed off through the loose cap by itself. This will be a about a turn or so. If its bubbling away like crazy then air was in there. You don't want it so loose that it falls away or stuff goes everywhere. then drive around a bunch more and stop and monitor the level every 5-10 minutes or so after your confident there will be no overflow. If the level is low to start it should not overflow as it warms up, but keep an eye on it. But don't get any in your eye.:p

This lowered pressure will allow the circulating coolant to help push and allow any air out, and rise into the reservoirs high point. As long as the pressure is built up in the system the air will stay where its at. During all this, note the level of the coolant in the reservoir as to if it's going down. If it is, then there was air in there and you need to keep adding until it's at the low level.

I do not believe your temp guage is high enough to bring on the fans, however, if air is trapped around the sensors then this will give a false reading and cause overheating without the gauge showing you. The sensor is measuring the air temperature and not the coolant temperature.

Cheers and better luck.

Does the 3.8 have any sort of air bleeder on it? If I remember it uses an "open" cooling system, so it actually has a radiator cap and such. Where the "closed" system on the 3.5 doesnt.

Ive seen open systems that had air bleeders, so if you can look around for one of them it might be helpful, sometimes theyre near the thermostat housing.

Yes I do have an open system in mine and I also have the air bleeder on top of my t-sat housing.Think that may be an easier way to do it pfofit...lol....:p

Should I have the car at normal operating temp before I crack open the bleeder?

O'k guys.My car is officially trying to make an ass out of me.I was just outside taking car of this bleeding thing while the car was running and guess what?

My fans decided to kick on when my temp gauge got to the half way mark!

Hey pfofit.both fans came on in low speed.I though you said only one fan comes on at low speed?....lol.

Anywho..The idiot light I'm refering to pfofit is the small red one that blicks telling you your rad is low on water.That is still blinking at me.I hit it with a screwdriver and now the light stays on for a few seconds then turns off so Now I'm thinking that dumb sensor needs to be replaced.

UGH!....I'm beginning to hate my car.

Hey pfofit.both fans came on in low speed.I though you said only one fan comes on at low speed?....lol.

No, I do not think I said that, although some cars use one one full speed and the other comes on full speed when it gets really hot. Depends on the specs of that pcm /engine.

If you reread all the posts from me regarding this issue, I'm sure I always used the plural "fans", at least the several that I reread. It is possible that i dropped the "s" once but should not negate the other 20 times when I didn't. Specifically here http://www.automotiveforums.com/vbulletin/showpost.php?p=6540639&postcount=4 I said I've attached the schema from a 2001 I think with the path for slow speed in red. Both fans are in series.

And here http://www.automotiveforums.com/vbulletin/showpost.php?p=6540931&postcount=8 If you do this, the fans should come on at low speed and then you can ignore the realys and go back to the sensor like the code P0118 points.

Anywho..The idiot light I'm referring to pfofit is the small red one that blinks telling you your rad is low on water.That is still blinking at me.I hit it with a screwdriver and now the light stays on for a few seconds then turns off so Now I'm thinking that dumb sensor needs to be replaced.
Or removed and cleaned. What does the manual say as per the blinking? The 3.5 does not blink that I know of. That's why I mentioned in my previous post that what was said earlier to that post, may not apply since we now know that you have the 3800

00UGH!....I'm beginning to hate my car.

Hey! me too. :icon16:

Actually,The book doesn't mention much on it at all.It just says if this light comes on your low on water.It doesn't say whether it blinks,Stays lite,Flashes,Nothing.

And for the sensor I did clean it out when I was up North on vaca and yes that thing was plugged with some nasty crud.Only thing in this sensor(don't know if you've seen them from the inside or not)Is a metal probe that looks like its made out of brass.

I cleaning it out but that dumb light refuses to go off so I'm guessing the internal electronics of the sensor are going out.I called Autozone and priced it.50 bucks!!

Damn them fools at GM!

P:S Ya didn't have to throw up quotes pfofit..I was just pullin ya timing chain....lol