Fuse box fan relay terminal burnt

[Pentalab]

When I got my tune from VMP, (came loaded on the X3 I bought from VMP) years ago, it allowed me to adjust the low speed fan thresholds (on/off temps).......and also the high speed fan thresholds (on /off temps). Each threshold could be varied over a huge (limited) range. Then the end user can fine tweak it.

My relay also burned up a few years back. Dunno why Ford didn't engineer it better, it's a dead simple circuit. Resistor is in the circuit to knock the voltage down to the fan, when on low speed. ( V drop across the resistor knocks the voltage down a bit). On high speed, the relay closes, and just shorts out the resistor, no more V drop..and max 14.75 vdc applied to the fan. The resistor should be sized to handle the load ( factoring in the eng bay heat)..and the relay contacts should be sized to handle the max load of the fan ( + a huge safety factor). How the heck they managed to screw this up with a marginal design is beyond me. All associated wiring should be sized correctly, along with an appropriate sized fuse.

 

[GlassTop09]

When I got my tune from VMP, (came loaded on the X3 I bought from VMP) years ago, it allowed me to adjust the low speed fan thresholds (on/off temps).......and also the high speed fan thresholds (on /off temps). Each threshold could be varied over a huge (limited) range. Then the end user can fine tweak it.

My relay also burned up a few years back. Dunno why Ford didn't engineer it better, it's a dead simple circuit. Resistor is in the circuit to knock the voltage down to the fan, when on low speed. ( V drop across the resistor knocks the voltage down a bit). On high speed, the relay closes, and just shorts out the resistor, no more V drop..and max 14.75 vdc applied to the fan. The resistor should be sized to handle the load ( factoring in the eng bay heat)..and the relay contacts should be sized to handle the max load of the fan ( + a huge safety factor). How the heck they managed to screw this up with a marginal design is beyond me. All associated wiring should be sized correctly, along with an appropriate sized fuse.

Oh trust me I agree w\ you completely.....but it is what it is so we gotta work w\ what we have.
All what this tells me now is if you want to go big boy power w\ this platform, save yourself the trouble twice & just rewire the system up front from the BEC to the fan w\ the right gauge wiring, terminals & 100% DC relays to accommodate 100% DC usage so this makes the low speed fan resistor\fan itself the "wear" part......which I believe was Ford's intention to do w\ the current setup by the way the OEM settings are configured to operate almost exclusively using low speed fan w\ hi speed setup for short term low MPH hi load operation only.........

 

[DieHarder]

The key is that a tuner sent you a known fan cooling profile that you have knowledge of to use in your PCM to know what\how the PCM would react to then check all the mechanical aspects of the system to know if the mechanical aspects are functioning as they should or not..................from a mechanical POV.
This still doesn't give you the tune side of this until you have the actual operational PCM fan control settings profile info in hand to then know that your issue isn't being caused\created thru the software........

IMHO this should be a requirement for all tuners to give the customer at least a copy of the actual fan speed control settings profile being used in the final tune so that the customer can\will know what\how this is set up to then have an expectation of how this will work....period. This is too important for a customer not to know.

It's 1 thing to burn the BEC terminals when you already know the PCM fan control setup is intentionally set up to run the system outside of it's design intentions beforehand......it's a whole 'nother situation to intentionally put a customer in this position w\o the customer's consent or knowledge of it............regardless of who does the tuning!

This happens FAR too often than it should be.

My tuner gives me a copy of my actual entire tune file already translated so that I can open it up in HPTuners VCM Editor software so that I can see it all.......cause according to my tuner, "You paid for the tuning & it's your car thus it's your tune. I could care less as to whomever sees the file. I have found that in the end, I end up getting more business from doing this cause it sends the message that I am very confident in my abilities to tune & isn't worried about any competition. I got nothing to hide."

His exact words. He keeps a copy of them for his records as well.

This is how I caught this w\ my car.....by using HPTuner's tune file comparison feature to compare my car's tune file w\ a sample '05 OEM SO tune file that comes w\ HPTuners VCM Editor software & saw that this had been changed to do exactly how Lito set up your "fan system checking" file.....my tuner didn't touch this part BUT Bama certainly did cause it was the Bama tune my tuner used as the base file (I had it already loaded in my PCM) & since we wasn't having any issues of overheating during the initial dyno session he assumed that all was good so didn't even look at it.... The only reason I had the Bama 91oct tune loaded up back then was to see how it would perform after I burned all the 87 oct fuel out the tank to fill up w\ 91 oct fuel prior to my dyno session at my tuner's direction (I used the original OEM tune set up for 87 oct fuel w\ the SCT Options set in it to use the FR Bullitt 85mm CAI, BBK 62mm TB, FRPIM & Kooks LTH's w\ cats so the rear O2 sensors enabled) & forgot to flash it back to stock.

Good thing for me is that I caught it all well before I began to have any of the symptoms even show up.

This is why I brought this up to bring this attention to the OP (the rest as well) because of what he typed as clues to this being a cause of his symptoms & shouldn't be overlooked.....

PS--for those who want it, here is a picture of an OEM fan control profile in a SO PCM for 05-09 GT taken in HPTuners VCM Editor:

View attachment 80642
Also just to point this out.......the low speed fan ECT target on\off settings you see in this picture represent the Ford designed\intended optimal thermal operating range for this 4.6L 3V engine......thus best efficiency out of it.

So, we have parameters based on speed as well as temps to engage fans? Interesting...Something I didn't know.

 

[Juice]

So, we have parameters based on speed as well as temps to engage fans? Interesting...Something I didn't know.

I did a simple experiment a while back, changed temp I wanted fan to come on. I could not tell if it actually made any difference at all. Too much 'logic' in these things, not a simple on/off setting anymore. (atleast on the coyote)

 

[GlassTop09]

I did a simple experiment a while back, changed temp I wanted fan to come on. I could not tell if it actually made any difference at all. Too much 'logic' in these things, not a simple on/off setting anymore. (atleast on the coyote)

Also some in the SO PCM as well, just not anywhere close to the sophistication level of a Copperhead or later Ford PCM.

Just to put this here to give context on the MPH setting control in a fan speed control in the SO PCM.....the main target control is the low speed ECT enable\disable range. What the MPH speed markers rep is to tell PCM where the car's forward motion thus natural airflow CFM rate drops below the fan's physical running hi speed CFM rate (Low Speed VSS enable) so if the car's MPH falls below this setting the PCM is aware that the car's natural CFM rate would be below the fan's physical hi speed CFM rate THEN according to where the engine's actual ECT is within the set ECT low speed ECT on\off range whether to turn the low speed fan on or not....as long as the actual ECT stays within the target range or is below the low speed ECT disable setting w\o the fan running when the VSS speed drops below this setting, then there's no reason to run the fan at all until the forward motion slows enough so the natural airflow drops enough to allow the actual ECT temp to rise above the low speed ECT enable setting (the upper ECT setting) then the PCM turns the fan on at low speed only then cycle the fan on\off as the actual ECT rises above\drops below the enable\disable low speed ECT settings....if all else is working properly. If car MPH is above the Low Speed VSS disable setting, this tells the PCM that the forward motion of car is providing more natural CFM airflow than the fan's physical CFM rate at hi speed....thus there is no reason for the fan to be run at all thus will turn it off completely....unless the engine's actual ECT rises into the hi speed ECT fan control settings w\ the car at speed then will override & turn fan on hi speed once actual ECT rises above the hi speed ECT enable setting then will turn it off once the actual ECT drops below the hi speed ECT disable setting......until the car's MPH drops back below the low speed VSS enable setting to then start looking for the actual ECT reaction to lowered natural CFM airflow rates again to start the process all over again. If during low speeds the actual ECT rises above the low speed fan ECT control & into the hi speed fan ECT control ranges from low speed ECT overheating (like stuck in extended bumper to bumper traffic on a hot day w\ AC on) then the PCM will override low speed & turn on the hi speed fan to try to maintain ECT within the hi ECT fan control setting ranges until the situation causing this to happen is rectified then all returns to normal operation once the actual ECT falls back into the low speed ECT ranges....rinse, repeat.

But this is essentially useless because if you're overheating at MPH speeds above the low speed VSS disable settings the hi speed fan speeds aren't gonna save you anyway due to car's natural CFM airflow is in excess of the fan's physical CFM rate or if stuck in low speed high AAT conditions causing engine ECT to climb exponentially into the hi fan speed ECT override ranges the fan running at high speed may not be enough on it's own to effectively control this.....only finding\fixing the\any mechanical reason for the ECT overheat IF the cause IS mechanical related....OR upping physical cooling capacity is the real answer\fix.....so save yourself the trouble & just up the cooling capacity from the beginning as much as you can stand to pay for then leave all this fan speed control set to OEM.

You'd be better off in the long run............

This is why it is fruitless to change the fan speed cooling profile settings for any of this w\ the only exception being the low speed fan control ECT target ranges (to change the engine's normal operational thermal operating window) or the 2 low speed VSS enable\disable settings (to tailor the MPH speeds to better suit a cooling capacity increase above the OEM rad\fan to reduce overall fan % DC operation.....meaning run even less time due to increased cooling capacity advantages but maintain desired cooling regimen). There's absolutely no reason to mess w\ the hi speed ECT enable\disable fan control settings (trying to lower them....this is the same effect as setting up the system to run continuously in hi speed for no good reason....unless you've tested the system on a dyno to see where the ECT heat soak levels out w\ a larger rad\fan combo at a WOT temp that is lower than the OEM settings to then match this up but even then it is not necessary so why mess w\ it).

This a lot but is an attempt to explain the "logic" in software behind the settings to hope to show why it is best to leave this alone & at OEM settings unless you have a good understanding of the coded logic operation behind this to then make good use of the setting changes so the system still operates properly thus maintaining some continuity of operation to keep the current draw load within reason.

Hope this helps.

 

[Juice]

I get the fan turning on on the track at tripple digit speeds. The hotter it is, the more the fan runs. I can tell because the control pack strategy turns on my gascap light when the high speed fan comes on. Temp guage or oil temp are both normal.
Figure that one out! lolol
I will look for speed setting in relation to the fan on/off, but I cant say I saw anything like that in the Advantage software.

 

[joshuamedina653]

I changed the terminal in the fuze box and soldered a new piece of wire into the fuse box. The tooth that sits into the terminal i changed seems fine, but the fan seems like it’s doing the same thing. Honestly stuck on what i should do, i am tuned by lito, could it be the tune? And would i have to adjust the fan temps or is it possible it’s still not making good enough contact, and the issue may possibly be in the wire or so?


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[joshuamedina653]

Fan turns on low speed for like a minutes, then comes on high speed and stays there, I’ve tested the car before changing out the terminal and relay would just over heat causing fan too shut off and car overheating, i test drove it after the terminal and wire being replaced, but fan is doing the same thing and relay is getting hot, so I didn’t want to risk car overheating again, so I haven’t drove it since, at this point im just confused on if it can be the tune or poor connection in the bec,


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[Juice]

Measure current draw if possinlble. Sounds like the fan motor is drawing too high current from age.

 

[joshuamedina653]

Measure current draw if possinlble. Sounds like the fan motor is drawing too high current from age.

The fan is actually new, can it still be drawing a lot of current?


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[Juice]

Possible, but odds are against it.

 

[joshuamedina653]

Is it possible the middle piece of the fuse box may have a weak connection? What if i connect that relay itself outside the fuse box, alone too see if it operates any different


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[GlassTop09]

Fan turns on low speed for like a minutes, then comes on high speed and stays there, I’ve tested the car before changing out the terminal and relay would just over heat causing fan too shut off and car overheating, i test drove it after the terminal and wire being replaced, but fan is doing the same thing and relay is getting hot, so I didn’t want to risk car overheating again, so I haven’t drove it since, at this point im just confused on if it can be the tune or poor connection in the bec,


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Hey Juice,
I finally woke up & realized that there is an OEM 2011 Mustang Copperhead 2048K tune file in HPTuners VCM Editor software so I opened it, went to the cooling fan tab under the System tab & took a picture of it for you to look at. And yes, it is MUCH more sophisticated than my measly old SO cooling profile! Picture below:

Your setup uses actual mapping to control fan speeds by not only ECT, but AAT, AT temp (if automatic trans equipped) & A\C Pressure (when A\C compressor is on). The left column sets the desired ECT to maintain, the min & max fan RPM's the PCM will control (actual operational fan speeds are dependent on factors set up in the mappings in right column) & the amount of delay time to tell the PCM to delay WOT disable (when in WOT the system will automatically ramp the fan speed up independently).

Even more of a reason IMHO to leave this stuff alone & just up physical cooling capacity.....unless 1 is willing to study this system to get fully familiarized w\ it's coded operations\functions before making any changes.....

At least our SO cooling fan profile is much easier to figure out!

Since you have a swap ('13 Copperhead PCM in '07 V6\GT simple relay controlled on\off fan speed control instead of PWM-operated fan speed control) I hope that the fan speed control setup in the Copperhead PCM control strategy will allow you to choose which 1 to use...............

As far as the gas cap light coming on during hi speed, hi load% operation fan speed control.....you might look into the CAN bus mapping some more to see if the IC is getting a signal from something else in the fan cooling I\O ID data from the PCM that it thinks is the EVAP gas cap loose........

You do have a Coyote swap'd S197 you know.......

Just a suggestion......

Fan turns on low speed for like a minutes, then comes on high speed and stays there, I’ve tested the car before changing out the terminal and relay would just over heat causing fan too shut off and car overheating, i test drove it after the terminal and wire being replaced, but fan is doing the same thing and relay is getting hot, so I didn’t want to risk car overheating again, so I haven’t drove it since, at this point im just confused on if it can be the tune or poor connection in the bec,


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I hate to say this but if this action you just posted above is going on while your car is parked, at idle & low load% w\o A\C on (ECT is low....like in the 195-208 range) then this is most definately a prime reason to check the fan control settings setup in the tune file as there is absolutely no reason for the hi speed fan to be coming on at all. If you have a general OBDII scan tool hook it up, go into live data & track the ECT PID data (read from the CHT sensor in cyl head) in conjunction to see if it is tracking w\ the running engine's ECT past thermostat but before entry into radiator....for the fan to be turning on hi speed at parked idle no load conditions the ECT has to be spiking very high (224*F +) if PCM is using the OEM fan control ECT settings then use a temp gun to read actual ECT on upper rad hose to see if it is tracking w\ the PID ECT reading.

If PID ECT is much higher than temp gun ECT this indicates either a bad CHT sensor or CHT sensor wiring shorted against cyl head (located under IM) or stuck closed thermostat. Both can cause this temp pattern & you'd have to remove the IM to fix either 1 so keep this in mind. Before going to pull the thermostat I'd suggest to check the CHT sensor & wiring 1st......CHT sensor is a dry sensor thus can be changed out w\o draining the coolant system......

If PID ECT & temp gun ECT track together high then this indicates a bad water pump, restricted\clogged radiator core (losing coolant circulation rate thru radiator\engine but thermostat is open).

If both PID ECT & temp gun ECT read low then it's the fan control settings in the tune file causing the hi speed fan to run on hi speed continuously (see note below).
Note: If you get here I'd contact Lito & ask for the exact cooling fan control settings (a simple snapshot of these settings would suffice.....) & then inform him of this issue if you got to this point as at this point the mechanical causes have been effectively removed to get these settings reset to stop the hi speed fan from engaging at this low of engine ECT range.

From the little I got from what you typed at the beginning of your post it would appear that you car's PCM is properly signaling both the low speed relay\hi speed relay since from your posting they don't engage at the same time.....this tells me that the PCM has control of both relays.........the fans are controlled by the PCM alone.......the tune has the fan control settings in it that the PCM uses to control the fans......

The OEM hi speed relay is gonna get hot due to having a potential 30A-40A of current drawn thru it's small connectors\internal contacts which aren't designed for 100% DC usage (continuous operation....hi speed fan wiring bypasses the low speed resistor so fan is getting very hi current into it's motor trying to spin at max RPM's against air friction to draw air thru the blades...this puts a load on it so the system has to increase current draw due to increasing heat (electrical resistance to current flow) thru relay, wiring connectors on relay pins in BEC & at cooling fan connector & the wiring itself between the BEC & fan motor to maintain enough current to maintain fan rotational speed thus heating up the relay, the connections & eventually the wiring. The longer this is running in this manner the hotter all this gets until something gives out....there is nothing else to protect this side except the 40A fuse in the BEC that the current is fed thru once the PCM has commanded the hi speed circuit on....except the PCM commanding the hi speed circuit off).

This is why Juice is suggesting to check the fan motor's amp draw while it's running to see if the motor is pulling excessive amperage....just because it is new doesn't mean it is good. The amp draw shouldn't be more than 10-12 amps for 12 ga wire....if amp draw is more than this then the fan motor could be suspect....but I'd get the fan control ECT settings reset before I'd replace a new cooling fan at this stage IMHO. Draw needs to be checked at the fan motor connector that is attached to the fan shroud to remove all else except the fan motor itself.

Hope this helps.................

 

[Juice]

Test for hydrocarbons in the cooling system.
You did say it overheated correct?
Leaking head gaskets will make the engine run hotter without any other obvious signs till it gets worse.
Easy & cheap test, so you dont go chasing an electrical issue when there is none.
Sorry for the potential bad news.

 

[GlassTop09]

Test for hydrocarbons in the cooling system.
You did say it overheated correct?
Leaking head gaskets will make the engine run hotter without any other obvious signs till it gets worse.
Easy & cheap test, so you dont go chasing an electrical issue when there is none.
Sorry for the potential bad news.

Good call........forgot about that 1!

 

[GlassTop09]

FYI.............(warning long post)

Ran a little test recently on my car concerning the cooling fan speed profile w\ my large rad\cooling fan (Mishimoto HP rad\13-14 GT500 cooling fan) w\ 195*F OEM thermostat installed.
AAT was in the low 60's when I did this. The cooling fan profile currently loaded in my car is the 1 that Bama had changed w\o my knowledge or consent & my current tuner didn't look at (BTW this is now fixed as we speak.......) so the low speed ECT enable setting @ 192*F, disable setting @ 188*F. Hi speed ECT enable setting @ 198*F, disable @ 194*F. Keep this in mind...............

Hooked up my scan tool & set it up to read live data looking at the ECT PID to see PCM generated temps thus the control side of the system then started up the car w\ all turned off to put the lightest load on engine during 750 RPM idle speeds.
I observed the fan was not running. Once the ECT came up to 192*F, the low speed fan came on as the control setting indicated (but the thermostat hadn't started opening yet). Approx 3 mins after observing this the thermostat opened up w\ ECT @ 194*F w\ fan running at low speed. Observed this for 40 mins....upper rad hose initially got hot then cooled down to being lukewarm to the touch w\ ECT holding steady @ 194*F (thermostat pinched coolant flow rate into rad to maintain ECT due to excess cooling capacity of rad\fan combo.....).
Then turned on everything to induce as much load on engine idle as I could (set HVAC to full cooling so compressor engages fully w\ no cycling & fan on hi speed, turned on headlights to hi beam & stereo system to load alternator) then observed system thru another 40 mins to see where the ECT would go. After 40 mins of idling under full load, the ECT climbed to & stabilized at a max ECT of 195*F from 194*F w\ low speed fan running.....ECT never got anywhere close to hit the 198*F hi speed fan enable setting to kick on hi speed fan. Upper rad hose never got any hotter than lukewarm (thermostat was still throttling coolant flow rate thru rad so not full open....going by my body temp being checked on occasion to be normal between 95*F-98*F this puts the rad hose temp to be in the low 100*F range....estimating 100*F-102*F....too lazy to get my temp gun as if I can hold the hose w\ bare hand w\o a glove on this is proof enough). So from this it says that during late spring, all summer, early fall & some times during the winter period in between fall & spring, my system is using hi speed fan running continuously to hold my engine's ECT at 199*F-206*F regardless of actual load (have recorded this many times this past summer & is riding ABOVE the hi speed ECT disable setting thus holds the fan on at hi speed once hi speed control is activated which overrides the VSS enable\disable settings regardless of actual operational ECT thus won't allow the system to reenter low speed operation OR shut down completely until the car is shut off).....when the designed intended operational engine ECT range is between 208*F-216*F w\ fan speeds either cycling or shut down as set by Ford..............

Looking at this now ask yourself this question......why would I need to have the hi speed fan come on, not only now but even when driving when the rad will be getting ram airflow CFM in addition to the low speed cooling fan's CFM rate, or even at all? So then why would I leave this system set up like this to put an undue electrical load on the hi speed fan relay in BEC, wiring circuits & connectors as well as the fan motor.....when the system clearly demonstrates that it's not needed.......except only when the engine is under heavy low MPH operating load only (which is what the Hi Speed Hi Load settings are for in the cooling profile....which operate using the PCM load% setting as the trigger to initiate this so not just out of the blue)? The truth is....even w\ the OEM rad\fan installed, my engine w\ it's current FBO configuration & HP\TQ rating would not have needed a fan cooling profile set up to have the hi speed fan coming on\staying on at this low of ECT setting....putting unnecessary burden\load on the hi side for essentially nothing thus setting 1 up for what most see as burnt BEC terminals, wiring, connectors over time....

At the least, from a logical mechanical perspective taking into account of what Ford's intentions were w\ this system, the hi speed ECT enable setting should have been set to say come on @ 218*F (to not allow the cooling system to get so heat soaked from waiting until the ECT temp hit 228*F to engage the hi speed fan thus having to run for longer, extended run times to regain ECT control), disable @ 214*F & then reset the low speed ECT enable @ 212*F but leave the low speed ECT disable setting alone at 208*F to have the system to engage hi speed fan just above the upper OEM normal low speed ECT enable setting to cool down to a setting above the new low speed ECT enable setting (that is still within the normal Ford intended engine operating ECT range) so the system only engages the hi speed fan long enough to drive the ECT back below the upper "normal" operating ECT range to then return the system back to the low speed fan control side to preserve the hi speed side from potential overheat thus BEC burnout but also will still allow the system to operate as normal as long as all ECT temps stay below the 216*F threshold, which means that the fan will mostly operate in low speed only at mostly idle\ 0 to low MPH speeds & be mostly completely shut down (wind milling) except when either commanded into hi speed from PCM commanding a hi load% situation OR a physical cooling system malfunction\capacity issue is occurring.....but not be intentionally put into an excessive electrical system overload caused by excessive hi speed fan usage caused by excessively lowered fan speed control settings (which is what the burnt BEC terminals, relay, connectors & wiring is a symptom of....excessive hi speed fan run time) when the engine's operating ECT range, regardless of usage, clearly doesn't need it.

This is a 1st hand true example of a user getting unknowingly set up for a future unnecessary potential hi side BEC terminal thus cooling fan failure....not because of the wiring gauge being used, or relay not being 100% DC rated but because someone did something in the tune file used to try to "fix" a perceived but unknown situation thru assumption then failed to inform the user that this has been done so the user doesn't know thus will also assume that all this is still normal or OEM.
This is a paid for service by the majority of users..........

So when the BEC is burnt up, "the root cause HAS to be something other than the cooling fan profile settings being set up in the tune in a way to cause this to happen because it didn't happen as soon as the tune was loaded up".........

The only way this can hold water is if the OEM fan control settings as set by Ford are still being used OR some fan control setup settings profile like what I have provided as an example above is used so to not interrupt\defeat the normal OEM low speed ECT operational design\intent of the system.

The whole purpose of the low speed fan's resistor is to PROTECT the low speed fan relay, wiring circuits, connectors from this electrical over load by being both the current V-droop control to intentionally lower the fan rotational speed & the "sacrificial lamb" to take all the heat generation from doing this work on a continuous basis if needed.....not the hi speed fan side (designed for critical, short term, temporary usage....not continuous operation).

Like it or not, this is what\how Ford designed the system to work thus all the materials used to make it.

Also demonstrates the importance of installing as much physical cooling capacity in these cars as 1 can.

If the statistics of all the 05-10 S197 cooling fan system failure rates were ever posted....then sorted between a full OEM cooling fan profile being used vs what\how most altered cooling fan profiles are set up thru a tune being used, I'll wager the results would so expose the altered tune side as a root cause by an order of magnitude that isn't funny compared to the OEM fan control settings profile as set up by Ford.

Can this be rewired\reequipped to run consistently at 100% DC to alleviate this issue from occurring? Yes it can. By doing this can it provide a level of protection from other component failures or tune cooling fan control setting mistakes? Yes to a degree. Does this really need to be done? TBH I don't think so in the larger majority of cases....but this is my conclusion.

Or do you only need to know the actual operational engine ECT ranges to then determine whether the current cooling fan settings being used make sense or do they need to be reset after all repairs to the BEC & associated parts are done, once found to be a contributor to this issue from the way the settings are commanding the PCM to operate the system? TBH this is the logical path to take 1st to then determine if a total reconfiguration of the cooling fan wiring\relay\connector system is really warranted as a simple reset of these settings could rectify the majority of burnt BEC wiring\terminal\relay failures.

But you won't really know until you check this out to verify it.

This is the true question to be answered IMHO as the BEC burning causing the fan to shut down completely & not reengage from loss of electrical operation can then cause the engine to overheat as well.

Sometimes IMHO it is wise to verify that something is necessary to be done before actually doing it....or to verify that it isn't the root cause of what has physically taken place....especially if you don't have any operational knowledge of how it is actually set up to operate AND someone else is known to have had access to it other than you..........to a system that can either make or break your engine & thus your wallet.

Your car thus your choice in the end.

If you'd rather shoot the messenger instead then fire away.......

Hope you get it all resolved.........................

 

[Juice]

Well sir, I had no issues with the fan or overheating wnlyith the v6. I only found the issue with tecausehe terminal starting to burn because of the swap and I had the BEC out.

Update: dug into fan settings, compared to stock file and my crate_6 based tune. High speed fan enable was brought down to 205* while stock setting is 223*. I set it to 215*. Im OK with 220* ect on track, now I should know at a glance that I'm at 215* ECT if the gas cap light comes on. LOL

 

[Mozart]

It's a problem many have had. The circuit is barely big enough when it's new. As the fan gets older it draws more current, the power distribution box will start to fry at the relay connection, which causes more resistance, which causes more heat, etc. Best thing is to move the relay outside the box. You'll need to separate the box to get the wiring figured out,IIRC. You may end up replacing the fan as well. But the relay relocation is the first thing to do.

I know this is an old reply, but is this what you are referring to? Bought a Mustang and saw this little configuration was done but not sure what for.

 

[MrBhp]

I know this is an old reply, but is this what you are referring to? Bought a Mustang and saw this little configuration was done but not sure what for.

View attachment 88026

Looks like it. Although I don't know why the old relay is still in place.

 

[DieHarder]

Looks like it. Although I don't know why the old relay is still in place.

Same thought here. Why would you leave that in place.... unless it's a spare?