[Juergen Schwab]

Hi Guys,


I have been lurking on this site for quite a while before pulling the trigger on buying a Smart ForTwo. I love the car and use it all the time for
errands into Baltimore and DC since we bought it about 2 Months ago. The only thing the car needed was new rear tires and that fancy looking
navigation radio kept cutting out. The A/C wasn't working too well so I figured I get to it eventually. Its a 2013 Smart Passion with now
31.000 miles.



Saturday my wife drove it downtown Baltimore and during stop and go traffic the engine temperature light came on, she pulled
over, parked the car and called me. We let the car cool down for a couple hours and once traffic cleared up we drove it home with
my ODB reader plugged in, it stayed under 200F at that point.


Once home I realized the Radiator fan doesn't come on, not when I crank the A/C, nor when the temps go above 200 (turned car off at 208).


So I read EVERYTHING I could find on several forums about the issue and came to the conclusion I'll pull the front off and go from there.


Front pulled off, I got my fat sausage fingers in there and disconnected the fan. Pushing on the blade there was ALOT of play which I'm sure
there shouldn't be. So I ran the connector to an auxiliary fan, turned the car on, cranked the AC to full but nothing happened.


I read that the relays sometimes go bad, so I swapped relay K59 with K57 which are identical in my car. I also checked fuse 14 and 28 which

both are good.



Turned on the car again, no juice at the radiator fan plug. So I pulled the SAM, opened it up to check for any dirt or moisture but didn't see anything obvious.


Is there anything else I can check? Another switch that I might be missing?



My plan was to add an AUX radiator instead of swapping the old one, so in case anyone wonders how big of a fan you could fit in there, I hope this will help you:


Maximal Length = 16 1/2 inches
Maximal Height = 14 3/4 inches



I had opted for the Rapid Cool 3680 12" that Pep Boys sells for about 50$, it was the biggest they had that would still fit (14" would have been too big as it is 15 1/4 at the highest point).


Now I still need to diagnose why I have no juice at the plug so I can get this beauty back on the road and my Ram1500 back in the garage.

 

[Juergen Schwab]

A quick follow up, I did some further testing:


1) Hooked up OEM fan to a small 12v battery, still turns but definitely broken, turn on sound for video:


https://youtu.be/t8NqKWdOg1M


2) Tested continuity between connector on SAM and the plug for the fan and there is good continuity. For future users who might
try to do this test, the cable marked below is the one. Its on the SAM on the left rear if you're looking at it from the driver seat.

3. Tried a different ground spot and still no power






Other thoughts:


I do recall when we first got the car 6 weeks ago there are a sudden noise for about 20 seconds from time to time that seemed
to kick in with the A/C Compressor, I figured it was a loud compressor but it could have been the fan.


I did relieve some pressure out of the A/C the week before the car overheated. We did that because it was way to high and caused the
A/C compressor to shut on/off every half minute or so. Relieving the pressure worked and the A/C compressor staid on, however it
still didn't put out any cold air. Could me messing with the A/C pressure be the cause of the power not getting to the fan assembly?




Or is it more likely that there is something not working right in the SAM?





I'm a little at my wits end on this one

 

[jimvw57]

The sound on the video sounds exactly like mine did when it had the broken fan mount. Not sure what to say about too much pressure in the A/C, I suppose if the compressor kicks out, the fan could quit.

My fan doesn't come on until temp gets up to around 215 or so. When you turn on the AC on high, the fan should come on and stay on.

 

[Juergen Schwab]

The sound on the video sounds exactly like mine did when it had the broken fan mount. Not sure what to say about too much pressure in the A/C, I suppose if the compressor kicks out, the fan could quit.

My fan doesn't come on until temp gets up to around 215 or so. When you turn on the AC on high, the fan should come on and stay on.

Yep, I did see your thread and solution to the fan, I basically duplicated your idea with the fan pep boys had, unfortunately when I tested the
new fan before installing it I realized I don't get any power to it.

So turning on the AC to high doesn't do it for me with getting power to the fan. I wonder if there is another way to turn on that circuit, like perhaps
there is an ODB2 Tester that can send that command to turn it on or something.

I doubt that the car getting over 200 again will do the trick as I would have heard the broken fan kick in when I first started investigating the issue

Since I gave up the hope of a quick fix I ordered the Behr fan that mounts in the OEM spot and will take it completely apart. Shouldn't be more than
maybe another hour or two from where I'm at now.

 

[jimvw57]

I have had the front end off on my current smart,thanks to a suicidal deer... and it is not too bad, just a lot of labor, and be careful with the engine coolant. Make sure you bleed the air out of the engine head. Charging the A/c can be a bit tricky to get to the charging ports and not all the charging connectors will fit in the small area.

It is common for the mount for the fan to break and that may be the problem and not the fan.Mine was messed up from the deer hit as were most of the front plastic so I replaced it all.

 

[Juergen Schwab]

Thanks for the info, shouldn't be an issue to get in there and swap it. I'm just at a loss when it comes to electrical issues, I wish there was a sure
what to ensure the fan gets power from the cars computer, or to verify that its at least trying. I'm still wondering if my A/C issue had something
to do with the fan not kicking on.



Is there maybe something I can jump/bridge to ensure the car tries to power on the fan, other than the A/C trick and letting the car heat up?



Maybe disconnect the temperature sensor (I'm not sure where it is on the smart though) that worked on my old Ford Probe?

 

[jwight]

"The coolant fan motor is switched on or off depending on the engine temperature recorded by the coolant temperature sensor and cools the coolant."

Is the engine coolant temp sensor good?

 

[Juergen Schwab]

I'd say it's good since it's sending me readings via ODB2

"The coolant fan motor is switched on or off depending on the engine temperature recorded by the coolant temperature sensor and cools the coolant."

Is the engine coolant temp sensor good? <img src="http://smartcarofamerica.com/forums/images/SmartCarOfAmerica/smilies/tango_face_smile.png" border="0" alt="" title="Smile" class="inlineimg" />

 

[toaster]

You have obviously dug deeply into the problem. You seem to have located the correct wire to the SAM, but the wiring diagram I have does not show a relay involved in the radiator fan operation... just some generic block on the diagram. Where are relays K57 & K59?

If it helps any... I hear no click of a relay from my SAM when toggling my A/C button, the radiator fan does turn on and off during this operation. I suspect a mechanical relay is not involved in this function.

Per the evilution website, the radiator fan doesn't come on until 100C (212F).
https://www.evilution.co.uk/index.php?menu=info&mod=990

Does your A/C compressor kick on when selected? If so, then a low pressure switch is likely not involved.

~toaster

 

[Juergen Schwab]

You have obviously dug deeply into the problem. You seem to have located the correct wire to the SAM, but the wiring diagram I have does not show a relay involved in the radiator fan operation... just some generic block on the diagram. Where are relays K57 & K59?

If it helps any... I hear no click of a relay from my SAM when toggling my A/C button, the radiator fan does turn on and off during this operation. I suspect a mechanical relay is not involved in this function.

Per the evilution website, the radiator fan doesn't come on until 100C (212F).
https://www.evilution.co.uk/index.php?menu=info&mod=990

Does your A/C compressor kick on when selected? If so, then a low pressure switch is likely not involved.

~toaster

Thank you, I wanted to make sure I do my best before wasting anyone's time on this topic


I read about the relay's here:


2007-2015 Smart Fortwo 451 Fuse Box Diagram » Fuse Diagram



Now looking at this link again in detail, I just realized I was checking relay 'A and C' on the above link ... DOHHH!!


I'll get back in there today to check if I have that actual K59 fuse, the right one this time

 

[Juergen Schwab]

Ok I got back in there, that relay doesn't exist on my 2013 passion. I fired the car up again and let it heat up to 220F
which took some reving around 1500-2000 rpm as it would not climb over 108 otherwise. So some reving and

AC blasting (only blasts worm...) I got it to 222F before I stopped. No power at the front to the fan.I turned on
my garage fan and cooled the car down to 195F in about 45 seconds to a minute.



I did notice some slight whistling/hissing sounds as if gas is escaping everytime I turned on the A/C coming from
under the dash or front of the car. Still wonder if my problems of the fan not kicking on are somehow related
to that AC.


But than again, maybe the AC doesn't blast cold because the radiator fan doesn't come on.



The compressor in the back is definitely kicking on.


The mystery keeps my mind racing...




EDIT: Does anyone know if the ground for the fan can be any ground location on the car or is the ground for the fan also in a closed circuit?

 

[Juergen Schwab]

Sorry for the multiple questions, here goes another one > The temperature sensor is indeed a sensor on the smart not a switch correct? So if the sensor reads the temperature, it sends it to the computer, the computer than tries to switch on the fan? Or is there an actual fan switch that could be stuck (presumably a relay, but doesn't look like there are any relays in the circuit)

 

[jwight]

According to alldatadiy.com, "The coolant temperature sensor [not a switch] detects the coolant temperature and transmits a corresponding voltage signal to the ME-SFI [ME] control unit (N3/10)."

The control unit (usually called the ECU) is located behind a panel in the right rear of the cargo compartment.

So it appears the fan is activated by the ECU based on coolant temp.

 

[toaster]

I believe the relays identified as K57 & K59 on your link are for the electric-drive smarts only. Fuse 28 looks to be the correct one for the radiator fan. No I do not believe the temperature sensor to be a switch.

Relays 'A' and 'B' are associated with the L&R turn signals and stop lights, while relay 'C' is for the heated mirrors.

I suspect your problem is in the SAM, likely on the processor board.

So apparently you have been inside the SAM. Does it look like this one from a 2009 MHD:
SAM unit relay configuration

Or this one:
Inside the SAM

Note that the relay arrangement on the processor board looks to be different between the two. I suspect yours is like the 2nd one.

Try tracing the pin from your connector to the device which drives it. Unfortunately I don't think it is a relay, but a solid state driver, possibly a motor driver.

~toaster

 

[Juergen Schwab]

Thanks for you help guys, my SAM does look like the 2nd one, only mine didn't have screws in it. I could not see any obvious damage when I had it apart nor signs of corrosion/ moisture. I guess I will dig it back out and focus on that. The signal not making it from the ECU to the Sam is unlikely right? And that's propaply not a function a car dealer could have turned off in the computer to hide issues with the fan for a quick dirty sale?

 

[toaster]

If I'm reading the wiring diagrams correctly... the ME-SFI (referenced by jwright above) communicates with the SAM over the CAN bus, then the CAN bus runs from the SAM to the instrument panel, and from there to the OBD connector. So since you are reading the temperature at the OBD connector, it would seem that both of the other modules involved would have access this this data.

If you know someone with a decent diagnostic system and the smart is in it's library, they should be able to manually toggle your fan on/off. This does not change any stored settings, it is just a function used for troubleshooting. Maybe check with a foreign car repair place.


OK, here is an alternative solution for you... probably a lot easier than tearing into the SAM.

There are fan controllers made for those who want to replace a vehicle's mechanical engine fan with an electric one. They are simple devices, available on Amazon or eBay, run $30 - $60, some have adjustable temperature controls and an input line for the A/C.

Use one of these to bypass the whole control issue. Attach its temperature sensor to the radiator and tap into the A/C clutch line for a signal and you're done! You can pick up switched 12V power from the SAM on terminals R1-R4 and there is a large grommet in the firewall near the SAM which has a wiring harness where you can snake the wires through.

~toaster

 

[Juergen Schwab]

Thanks Toaster, I do really really want to get the OEM setup to work now that the quick fix didnt work.

I pulled the SAM again today and tested every relay, I found the specs for them on this site:

https://cdn.sos.sk/productdata/5f/7f/a79387b6/g8qe-1a-dc12.pdf

All the relay's on the SAM checked out with the proper resistance. There is also voltage at the 40amp fuse.

I called my local Mercedes Garage and they said bring over the car but put the front back on first, I really
didn't feel like putting it on and them pulling it back off so I just installed the new OEM fan myself.

I'll post a vid of the old one, its was wobbling bad. I'm pretty sure if it ever came on I would have heard
it inside the car.

Once I got the whole thing back together I'll bring it to Mercedes for Diagnostics. Or just buy the 500$ Autel
since that would also allow to program a spare key for the smart and my ram1500.

If they can't figure it out either I'll wire the OEM fan in via the relay option you mentioned.

 

[Juergen Schwab]

Here is the video of the fan play. The frame was fully intact and the bolt on the fanblade tight. Blade wobbled alot.

https://youtu.be/-K1QyQCEKJs

 

[toaster]

That does look loose, but I've never dug into the fan on mine... yet.

Can you try making a resistance measurement from the fan's power lead to chassis ground? Not looking for the resistance of the fan itself, but of the driver on the SAM. Do it with the fan disconnected and the ignition off... check with both polarities of your meter. Maybe also check it with the diode function of your meter. I suspect a shorted or open driver on the SAM.

~toaster

 

[Juergen Schwab]

That does look loose, but I've never dug into the fan on mine... yet.<img src="http://smartcarofamerica.com/forums/images/SmartCarOfAmerica/smilies/tango_face_surprise.png" border="0" alt="" title="EEK! Surprise!" class="inlineimg" />

Can you try making a resistance measurement from the fan's power lead to chassis ground? Not looking for the resistance of the fan itself, but of the driver on the SAM. Do it with the fan disconnected and the ignition off... check with both polarities of your meter. Maybe also check it with the diode function of your meter. I suspect a shorted or open driver on the SAM.

~toaster

Yeah compared to the new fan there is a world of difference in the level of play. I'll measure resistance when getting back Wednesday or latest Sunday. I did get the Autel today (prime) and I'm AMAZED at the level of detail this little tablet is giving me. Like every bulb, switch, etc is there, live. And the radiator fan is displaying a short circuit code...so I deleted the code and once I get the coolant back in will check if that maybe prevented it from trying to turn on the fan. If it doesn't turn on I'll have to do more searching for that potentially still open circuit.

The milage info for the fan code doesn't make any sense since the car has 31000 miles but that's the least of my worries 🙂

See how many times that code was triggered..