Will not turn on in my 2007 Fit. Fuse is good and so is the relay as the fans will operate with the AC turned on. I attempted to short the two terminals together with a paper clip on the coolant temp sensor plug but still no fans. This is the sensor located on the bottom of the radiator passenger side (correct?).

Anything else in that circuit to check?

Thanks, Walt

 

The radiator cooling fans are controlled by the PCM via the AC system, and the temperature sensor in the bottom of the radiator (ECT2)
ECT2 is completely independent of the ECT1 on the engine.
Sure seems like very few scanners can display the value of ECT2.


The fans turn on when that sensor in the bottom of the radiator reaches around 212*F.
This could take a looooong time depending on ambient temps and wind.
A breeze blowing through the radiator could remove enough heat that the engine might not need the fans at all.

Do NOT short any wires with a paper clip.
The PCM should recognize an open and a short as faults, not valid input values.
You might have set codes for that sensor. (P2183/P2184/P2185?)

HTH

 

I am getting a flashing to solid warning light on the dash of an overheat problem so I assume the fans are not operating at designed set point. Also, when my daughter arrived home I could see some signs of antifreeze around the area of the overflow tank.

So your advice is to scan with an ECT2 scanner?

Thanks,
Walt

 

That's a problem.. A huge problem.


How many miles on the car?
Don't assume this unless you can prove your theory. There are many other reasons an engine may overheat......

Low coolant level in the radiator is certainly among the most common causes of overheating....but then one has to figure out WHY the coolant became low in the first place.


Open the radiator and inspect the two areas in the opening for erosion damage (neck interior must be smooth where the two rubber gaskets on the radiator cap must seal)

If ok, refill the radiator to the top, run and burp air from the system.
Adjust the level in the reservoir to the max line on the bottle.

Then see if this simple refilling of the system brings operation back to normal, even if only for a short time.




No. There is no such thing as an ECT2 scanner.

ECT is an acronym that stands for Engine Coolant Temperature (sensor).
ECT1 and ECT2 are acronyms that identify a specific ECT --- because this system uses more than one coolant temp sensor input to the PCM.

ECT1 = Engine temperature
ECT2 = Radiator temperature

Just about every scanner that can display live operating data will display the #1 coolant temperature sensor value.
It's been my personal observation that very few scanners are able to display a value for the sensor in the bottom of the radiator.


By the way, make sure you erase the codes you set when you shorted the wires for the sensor. Then re-scan to make sure it's not setting any new codes.

 

Scanner will read an engine temperature; the fan should start at 90 degrees C
if fans are not running at 91 and above turn ON the ac. If fans still not run check the 7.5 A #10 fuse under dash (defective a/c switch causes it to blow, disabling power to fan relays)

 

I believe OP did say the fans work when the AC is turned on?

OP also hasn't posted back regarding the coolant level in the radiator yet.

If the coolant level is low, or if the thermostat is stuck closed,
liquid can can overheat inside the engine---(and computer turns on the warning light in the Fit) but that may not get the radiator hot enough to turn on the fans.

I see this situation often with the 1.7 Civic engine that's rather well known for head gasket failures many people can't figure out...... overheating without the fans turning on is just one of several possible symptoms one might experience when the coolant level is low.

The L15 engine is not immune to head gasket problems at high mileage.

 

ezone, sure is great having people on here who really know these cars. Makes newbies like me very lucky. thanks.

 

Thanks.
I've dealt with this issue many times so it's not out of the ordinary for me, but there are many other issues brought up in owner forums that I don't ever get to see in person so I get to learn a bit here too.

I picked up our high mileage 07 Fit for my GF to drive just because they have been almost bulletproof (IMHO) compared to some other models that would have been in the same price range at the time I got it.

 

My Fit has 90,000 miles. Reset the codes and topped off the antifreeze that was about 1/2 to 3/4 quart low. Drove for about 45 minutes with no overheating issues however, it was only just above freezing today. Tomorrow I will clean up the engine bay and have a closer look for leaks but nothing obvious was found. The area around the filler neck looked fine also went ahead and replaced oil while I was at it.

Thanks for all the great suggestions.

Walt

 

Can anyone comment on the functional roles of the passenger side fan and the driver side fan? I took in my 2008 Fit Sport to the dealer for an AC check as it has not been blowing very cold. They told me A) Freon was low, and B) the passenger side fan does not engage even under any circumstances. They wanted $1200 to replace the fan and recharge the AC system, but could not guarantee this would fix the issue. The AC blows moderately cold, but not ice cold.

I took the car back and ran the AC on MAX for about five minutes (ambient temp 80 degrees F) and the compressor came on and the driver's side fan was running, but indeed the passenger side never came on. I bought a can of R134 and checked the Freon pressure on the low pressure line and it was normal (within the range on the guage), so I am a bit skeptical about the advice I am getting.

Thank you for any insight.

 

How does the AC do at highway speed? Is it cool enough then?


Fix the fan motor problem first. Then see if there is improvement in the AC at idle and low in town speeds.

 

First thing to check, is the AC fan relay working (They click you can feel them with your finger. ) Its in the fuse box under the hood. Find them on the fuse box lid and have someone turn the AC on and off while you feel of the relay. If it clicks the next step is a voltmeter to the connector for the fan at the fan end, volt meter between the pins should turn on and off when the system tries to cycle.

Then,,, check every single fuse,,, there are some weird relationships between circuits in the fit (GD)

AS far as heating and cooling,,
I recently ended up on this path and it was a small crack in the radiator near the hoses up where it was nearly impossible to see. Never really leaked water, just steam as it was on top of the radiator.

If its the original radiator , you might consider pulling it out and taking it to a radiator shop and getting it pressure tested,, the good thing is they are available fairly reasonably from rock auto and other sources, I just replaced the plastic tanked one with a double core Aluminum unit.

The red overheat light is a BAD thing, it turns on north of 275 degrees which is blown head gasket territory.. (I just had to do the gasket,, FYI if the head gasket blows the odds are it will over-pressure the radiator and ruin it. (Blew the tanks off mine.. We'll it loosened the crimps anyway. )

The driver side radiator is the cooling system one, the passenger side is AC.
FWIW my drive side one never comes on with the ac, the ac one has no link to the drivers side. They seem to run independently on my 2007.

 

Thank you for this info. I will perform these checks and follow up. I have not had any warning lights so far

 

Uhhhh.....Your might want to check your own car a little closer, it's not supposed to be that way

I'm staring at a 07-08 Fit wiring diagram here...it shows those two fans are set up to always run together.
Each fan has its own relay and fuse, but no matter which system (AC or ECT2) makes the fan request to the PCM, both fan relays are triggered at the same time by the same PCM terminal (E12).

Fuses involved are
#10 (7.5A) in the dash fusebox (feeds the coils of the fan relays)

#10 (30A), 11 (30A) in the engine compartment fusebox (one for each fan)


HTH

 

Yep.. Just one of the many things that don't match in the 3 different copies of 07 fit wiring diagrams I have access to, including the factory electrical manual and a general factory service manual with almost the same diagram sets.. ,,, one of mine shows what you describe the other shows a different pin for the main cooling fan. I'm still checking wiring,, its a B**** under that dash..

 

I was looking at Hondas ETM (US/Canada) online.

Maybe one of your diagrams covers some other markets (countries) version of the car?

 

I have 2 versions of the US electrical and they match about 98% The JDM version mostly available on line has a BUNCH of different wiring than mine.

But you go time thinking and I went out and played with the fans again, here's the funny part, BOTH fans do come on with the AC, but only the drivers fan comes on with the temperature.. WTH.. Somewhere there is a Honda electrical engineer deserving a back alley beat down..

 

On my car both fans are operating with AC (manual a/c) but I have not checked them with the temperature.
According to schematics (from Mitchel On-demand),
-- both fans are connected in parallel and run on one speed
-- they share common ground points
-- both relay are energized when ECU grounds the green "coil minus wire" (E12)
-- the B+ power to relay coils comes from Fuse 10 (7.5A) under Dash box via junction connector B
However: the power to the motor contacts in relays comes from DIFFERENT sources
--Fuse 11 under hood ( 30 A ) provides power to A/C clutch coil AND "condenser" fan motor (located in the passenger side)
-- Fuse 10 UNDER HOOD 30 Amp provides power to radiator fan motor (driver's side)
SO ACCORDING to schematics BOTH fans should run with a/c or when temperature is hot

 

Yep thats the way the Brown Honda manual shows it..

 

It actually looks a lot simpler than 2 speed fan system on 83-2000 Camry (when fans are connected either in parallel or in series for low speed a/c operation)
Each fan can be tested individually by applying power to the fan directly from 9 volt Duracell or equivalent battery (alkaline type); if fresh battery cannot make fan to spin the fan is questionable and has to be replaced.
If a/c clutch relay is stuck on and a/c clutch coil has lower resistance than fan motor, the electrical current will go to the a/c clutch coil leaving no power to motor to spin. To test this theory, the a/c clutch relay has to be pulled out; if fan works after that the a/c coil relay must be tested and probably replaced