cooling fans

[Trevor]

Mike,

Now that you have checked for ground faults we can take the diagnosis further. Things are complicated as the fans are multi speed and there is a second permanent ground circuit and this must be keeping the negative alive for one of the speeds.

You must now place the temperature sensor as number one suspect component. If you have an ohm meter you can check it. When cold and unplugged the resistance across the two terminals should measure between 2000 & 3000 ohms. If the resistance is much lower than this you have found your problem.

Also if the fans stop when you unplug the sensor this should also indicate a faulty sensor.

[michael]

WHICH SENSOR AND WHERE?

Took today off so was able to do a little research on the sensor thing. Tried to find the service records but all I had was about a million Jiffy Lube receipts.

Looks like there are 2 things doing coolant temp sending stuff. One is the "coolant temperature sensor" (CTS) and the other is the "coolant temperature gauge sending unit". I thought one would feed the other but after checking the wiring diagrams found that the CTS feeds directly into the Engine Control Module. My guess is this sensor is your bad actor.

Location for both is either "left cylinder head" or "left rear of waterpipe below aux. air control valve" - your choice as both locations were given for both sensors - they are in the same location. The CTS has a blue/black and a green/yellow wire set.

Good luck - those fans going all the time is a pain.

Scott

[michael]

O.K. I'm stumpped. I just developed that long crack across the top front of the radiator, what gives? I guess the radiator. I bought a coolant temperature today and put it in and I think the car runs better, if that is possible but it still didn't fix the fan problem. I checked the ambient sensor and it's fine, no where near the external tranny cooler. Did I mention I put a 13lb. radiator cap on, could somebody tell me if it's to much. I thought mabey I might have an air pocket somewhere in the system that is preventing the coolant from making contact with a sensor, once again thanks for the input.

[michael]

trevor, you mentioned checking for ground faults I'm no to electronicaly inclined could you tell me how to check for shorts if you can't think of anything else.

[Trevor]

Originally posted by michael
trevor, you mentioned checking for ground faults I'm no to electronicaly inclined could you tell me how to check for shorts if you can't think of anything else.

You have set me rather a task as you are not electrically knowledgeable I presume as well being not electronically inclined.

Between us we could become involved in writing a book here ! If I have thoughts on any more simple checks you could make after again looking at what data I have I will get back to you. I will do my best within the time I have available.

[michael]

I didnt mean to scare you, iknow if you drop a wrnch in between the pos + ng batt terminals it's pretty cool. I just don't know how you got what you did from my removal of the relays. First I'd like to check the relays to makesure they work then see from there if there is a short from the fuse box outward. I know how to use a voltagemetr and a test light and I know what relays do. Lets go from there.
I believe we can eliminate th fans themselves, the coolant temperature sensor, and my temps are always normal so the coolant flow is ok and the heater blows hot air with no smells or fumes

[Trevor]

Mike lets get back to basics and trace the sequence of events.

(1) Were the fans running continuously before you started having to install a new upper radiator hose ?

(2) The fans run as soon as the ignition is turned on or only after the engine is started ?

If you pull the fuse in the RH corner of the fuse box the fans stop but do not go back on again even when they are supposed to when the A/C fuse is unplugged. This is interesting but confusing.
(3) Can you confirm and elaborate and identify the fuse by its label as I am not sure which it is.


Lee mentions a Ò trinary switch Ò which works via the A/C system. P.S. Checked this and it should not have any effect unless the A/C is swtched on.

ScottÕs experience indicates the (water) temperature sensor but this you have now replaced.

Scott also, mentions coolant temperature gauge sensor. I will check but think we can rule that one out.

You advise that you have bought a coolant temperature ( sensor ) and put it in. Ambient sensor is no where near the tranny cooler. You have thoughts re an air pocket ( or lock ).

Only just turned up your latest post and now that you confirm you know more than you previously let on we can proceed further. Please answer all the questions. I am not being pedantic and I am sure you appreciate we must use a logical approach to this rather vexing issue.


P.S. Looking again at your pictures I find that you show relay (4 Fan RH1)
when removed turns the LEFT hand fan off. It should turn the Right hand off. (4) Is this correct or is your picture not correct ? Did you by any chance mix up plugs or wiring when attending to the faulty radiator ?

This is all very difficult from so far away. If I could only be in contact with your car I could make several checks in minutes.

(5) Turn on ignition and when the fans are runnimg remove relay (1 GND) which should make no difference. Exchange this relay with (3) as a means of testing by substitution and note the results.

I have given you quite a list to answer but I can see no other way I can progress the diagnosis. You may wish to give up and go to an auto electrician.

Sorry that the CTS did not fix your problem. The wiring diagram indicates that it is in a loop with the ECM, informing it of engine coolant temperature, which would cue it to turn on the fans. The only other suggestion is that you check out the fan relays, located in the compartment next to the windshield wiper fluid.

I would suggest that you get a copy of the wiring diagram and take Trevor's cue to get out with the ohm meter and go to work.

I would also suggest you get a Bible and pray frequently.

Good luck....


Scott

Found this while researching another's question.

The Engine Coolant Temp. sensor should measure:

2000-3000 ohms at 68 degrees F.
300-400 ohms at 176 degrees F.

[michael]

(1) Were the fans running continuously before you started having to install a new upper radiator hose ?

They started running cont. after I installed the tranny temp sensor on the inlet line of the radiator. This is when I first noticed it.

(2) The fans run as soon as the ignition is turned on or only after the engine is started ?

The fans run when you turn the ignition on.

If you pull the fuse in the RH corner of the fuse box the fans stop but do not go back on again even when they are supposed to when the A/C fuse is unplugged. This is interesting but confusing.
(3) Can you confirm and elaborate and identify the fuse by its label as I am not sure which it is.

See attached file

Lee mentions a Ò trinary switch Ò which works via the A/C system. P.S. Checked this and it should not have any effect unless the A/C is swtched on.

I unplugged the trinary switch and nothing changed.

ScottÕs experience indicates the (water) temperature sensor but this you have now replaced.

Correct

Scott also, mentions coolant temperature gauge sensor. I will check but think we can rule that one out.

I agree, the guage is giving accurate readings.

You advise that you have bought a coolant temperature ( sensor ) and put it in. Ambient sensor is no where near the tranny cooler. You have thoughts re an air pocket ( or lock ).

I thought mabey their is trapped air in the crossover pipe where the temp sensor is, preventing the sensor from getting access to coolant.

Only just turned up your latest post and now that you confirm you know more than you previously let on we can proceed further. Please answer all the questions. I am not being pedantic and I am sure you appreciate we must use a logical approach to this rather vexing issue.

P.S. Looking again at your pictures I find that you show relay (4 Fan RH1)
when removed turns the LEFT hand fan off. It should turn the Right hand off. (4) Is this correct or is your picture not correct ? Did you by any chance mix up plugs or wiring when attending to the faulty radiator ?

No chance I mixed up any plugs, I will check the relays again in the morning and get back to you with the results. I believe they now have a different reaction when removed than what I posted last time. And last time I know was correct.

This is all very difficult from so far away. If I could only be in contact with your car I could make several checks in minutes.

NEWS FLASH!!!-I RESET THE ECM AND THEY STARTED WORKING PROPERLY FOR ABOUT AN HOUR.

I fixed the crack in my radiator with great success, thanks to a post on the site. I think though it might be time to start saving for a new one. I was thinking mabey I'm getting excess pressure from a blockage or the new thermostat might be sticking. I'm not ready for a specialist yet trevor especially the dealership who sold me some $1000.00 spark plugs, and said it was so expensive because they had to take the engine out of the car.

(5) Turn on ignition and when the fans are runnimg remove relay (1 GND) which should make no difference. Exchange this relay with (3) as a means of testing by substitution and note the results.

I'll get back to you on this one in the morning, and again thanks for the help and patience.Correct

[michael]

just another thought, if my thermostat is sticking wouldn't that account for the pressure in my upper rad. hose and explain why the top half of the rad cracked. Also if there is not adiquate flow of coolant the CTS would only read hot water, thus keeping the fans on.

[Trevor]

Mike I am making a summary of things so that we can keep on track. I hope that Cris. does not mind our extensive use of what he provides as it is good practical stuff.

[They started running cont. after I installed the tranny temp sensor on the inlet line of the radiator. This is when I first noticed it.]

[ScottÕs experience indicates the (water) temperature sensor but this you have now replaced. ---- Correct.]

[Scott also, mentions coolant temperature gauge sensor. I will check but think we can rule that one out. ----I agree, the gauge is giving accurate readings.]

[I thought mabey their is trapped air in the crossover pipe where the temp sensor is preventing the sensor from getting access to coolant]

[No chance I mixed up any plugs, I will check the relays again in the morning and get back to you with the results. I believe they now have a different reaction when removed than what I posted last time. And last time I know was correct.]

[Removing the A/C main fuse turns the fans off.]

I will investigate this further as a possible new clue.

[NEWS FLASH!!!- I RESET THE ECM AND THEY STARTED WORKING PROPERLY FOR ABOUT AN HOUR.]

This surely means that a signal is being received by the ECM and being transmitted to the fan relays, or and not good, ----- the ECM is retaining a recorded fault which no longer exists and sending an error signal to the fan relays.

Things are getting involved as we must now suspect the ECU but let us not jump to expensive conclusions at this stage. We must stick to a planned approach and I will await your further test findings.

Re your second post : ------------

A good thought Mike. You are doing the right thing by back tracking on the sequence of events involved which is number one in fault diagnosis.

You could be on the right track but if the thermostat is stuck closed your car will be running continuously at an excessive temperature. What does the temp. gauge say to you about this ?

The radiator cap would be the suspect item In respect of excess pressure.

However on checking back on the thread I now find you have posted the following : -

[I believe we can eliminate the fans themselves, the coolant temperature sensor, and my temps are always normal so the coolant flow is ok and the heater blows hot air with no smells or fumes.]

[Did I mention I put a 13 lb. radiator cap on, could somebody tell me if it's to much.]

----N.B. The specs. for the cap show 11 -14 PSI so you have the correct cap.

I agree, the ( temp.) gauge is giving accurate readings.

We are it appears back to square one on this one.

[michael]

New results from unpluging relays/fuses

[Trevor]

Thanks Mike that makes a lot more sense.

In particular the slowing rather than stopping of both fans after removing the ground relay. The previous information on this through me completely off track !

I will get time to do some more circuit tracing shortly and get back to you.

P.S. Straight off the cuff. ---- All this started directly after you installed the water temp. sensor. If that circuit is shorted e.g. a short in the lead or prpblem with the plug this will be your problem. Check the plug carefully again for bridged contacts or connections at the sensor. Then unplug the sensor as I previously requested and see if the fans stop. I can not recall you having reported on this test. If all is OK I will tell you how to check the complete circuit.