2013 GT500 Cooling Fan Concern

So, ever since I bought this car, I have been restoring it and dealing with cooling issues. The car is required love and still in great condition. I recently got a tune only from Lund because I wanted the nGauge to monitor some parameters in the car. The situation I am investigating now is the following.

Driving the car on 87-91 deg Florida heat, the car ECT goes all up to the 230 on traffic, and as soon as I get to speed, and air flows, it drops down to 194 deg. The engine feels extremely hot and some places are way too hot to touch in the bay and even the chassis of the car.

The high-speed fan works when I jump pin 30 to 87 highlighted in yellow. On that same relay section, pin 85 highlighter in red, has nothing to go off: no ground and no positive. I am not sure if the PCM supply the ground for the loop to close from pin 86 to 87 or what’s going on. What I know is that if the power runs from pin 30 to 87 the fan will turn on.

The low-speed fan: When I jump pin 30 to 87 highlighted in blue, the fan won’t turn on, but the ground is present on pin 85 highlighted in green for that relay area.

I am not sure if it is a matter of cooling fan operating procedures and everything is good or if indeed, I have a fan issue. I checked all the connections under the relay box (SJB) and no burned plugs or cables. I checked the fan plug and all looked good. If any of you Ford family knows something, I might be missing please let me know. I need to look for system operation to see if all I might need is a tune update to have the fans work better.

Can't speak to your elec. issues.
But if the car doesn't already have a 170* T-stat, it's a low $$$$ way to increase cooling. To get the max benefit, the hi / low fan settings have to be changed in the tune.

1 Alibi 2 said:

Can't speak to your elec. issues.
But if the car doesn't already have a 170* T-stat, it's a low $$$$ way to increase cooling. To get the max benefit, the hi / low fan settings have to be changed in the tune.

Click to expand...

Tracking that and its on the way but I want to make sure I fix any issues prior to start altering normal operating cooling system. That way I am not chasing issues later on top of upgrades.

The main reason I say this is because I just ran into a post that another person had with similar issue. He end up finding that normal operating temp for the low fan to kick was 215°F but I am not sure if that is for the 2013-2014 GT500. I have a repair manual but is not very specific. This is what my manual says:

The coolant temperature range per 2013 GT500 Repair manual

o Cold > 32-138°F
o Normal to Mid > 140-248°F
o Hot Bad > 253°F

I personally think anything over 215°F is a little crazy. My IAT2 during datalogs are 140-155 at that range. If the car is around 194-209°F my IAT2 are around 129°F - 136°F. I think for Ford to have any 2013-2014 GT500 running at 230-235°F on traffic as normal is INSANE!!!

The stock fans are set too hot before turning on for sure. It looks to me like your low speed fan isn't coming on at all. Do you ever hear it running?

#85 is relay coil ground only. Not fan ground. If you jump 30 to 86 the relay should click and the fan come on.

By going from 30 to 87, you are bypassing the relay and sending power straight to the fan.

I would check the plug on the fan shroud, maybe even pull out the fan and see if anything is obvious.

The 170F stat isn't going to fix anything. It will just delay the overheating by a couple minutes. Unless you actually have a thermostat issue. I would still change it but I doubt that is the core problem.

Have you checked the function of the cooling fan resistor? If it fails it may not be turning the low speed fan on and you are only getting the high speed fan operating.

It's housed in the fan housing next to the fan its self. has a little metal cage around it on the radiator side and the fan plug on the engine side.

tjm73 said:

Have you checked the function of the cooling fan resistor? If it fails it may not be turning the low speed fan on and you are only getting the high speed fan operating.

It's housed in the fan housing next to the fan its self. has a little metal cage around it on the radiator side and the fan plug on the engine side.

Click to expand...

I am 99% sure that is the problem. It all points out to it. I ordered one, but it will take 4 days for delivery. After I install it I will jump the low fan relay and verify that it runs. Thanks


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If you have a Lund tune, you can also ask them to change the specs of the fan management. They already do that if you told them about the *170 tstat, or any heat exchanger fans you might have installed.

Well, i'm 100% fixed. I had just about every cooling issue you could imagine but now i am an expert troubleshooting power/cooling issues.

Issues i found in sequence below:

CAC Pump relay bad> insane power loss after 20 minutes of driving the car. Not even second gear short shift squeal on the tires.

nGauge showed ECT up to 135 > Low speed fan not running at 208 target but runs on a/c activation. Jumped the relay pin 30 to 87 an nothing. Replaced fan resistor and fan runs on target.

Bonus- Thermostat broken inside housing> Replaced thermostat with Reische 170. When i took the old 192 out, the rear portion came off the thermostat.

So pretty much if your car is ruining hot, and i mean you can feel the heat coming through, check the fans, and ultimately thermostat. Jump the relay pins 30 to 87 on both high and low speed and if they run and the relays are clicking good, then all those components are ok and maybe is the thermostat.

If you have power loss on top of that and thermostat, fans, relays are good, check the CAC pump relay, jump pin 3 to 5 and cinch the bypass house, if the pump is flowing then you need an exorcist because i don't know what else could it be.

We can check voltage and proper continuity but i am old school and lack patience, so i jump and apply power directly as safe as i can to whatever i can and go from there.

I would not have put a 170 thermostat in place if the OE 192. Maybe 185, but it'll run cleaner if it runs hotter and it's setup from the factory to run the higher temps.

But it is satisfying to resolve an issue you have been chasing.

i tested the car and the temp gets all the way up to 180 quick here in Florida, and to day that i did the test is the coldest day of the week so far at 89F. When is 90s up there, i bet the car will benefit from it.

It may. Or it make no difference. Or it may hinder something. Just yesterday i was reading about too cool of a thermostat in a Foxbody adversely affecting fuel economy.

Heat in an engine isn't a bad thing so long as it can be managed. High heat burns cleaner and enhances efficiency.

tjm73 said:

It may. Or it make no difference. Or it may hinder something. Just yesterday i was reading about too cool of a thermostat in a Foxbody adversely affecting fuel economy.

Heat in an engine isn't a bad thing so long as it can be managed. High heat burns cleaner and enhances efficiency.

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You are correct about heat burns cleaner, hence the reason Ford engineers make this engines run hotter for fuel economy but that not quite why i bought the car. I am about to test the performance change soon on that regards, but let me tell you, i am more concern about IAT2 temp than fuel economy. if my fuel economy goes down but my engine performance goes up that is a win.

Just after contacting a few pros in this industry, seems that this lower temp thermostat change is nothing to worry about. Other GT500 had done far greater changes affecting the cooling of this car with the goal of performance and the car still run great for daily drive. Mine is not quite a daily driver car, mine is more of a weekend if any.

If the thermostat makes the car run poor, i will change it but i haven't got any negative feedback from any of the 170 thermostat users, in fact all of them seem to be in high temp areas and they love it. I will report if i find any negative results from it.

Now that you have everything in working order, your first upgrade should be an aftermarket heat exchanger.
VMP sells a very nice unit. For what it’s worth, I run an Afco w/o fans on my 08 TVS Bullitt, and even on 110*+ las vegas summer days my IAT is no more than 30* above ambient at stop lights.

golkhl said:

Now that you have everything in working order, your first upgrade should be an aftermarket heat exchanger.
VMP sells a very nice unit. For what it’s worth, I run an Afco w/o fans on my 08 TVS Bullitt, and even on 110*+ las vegas summer days my IAT is no more than 30* above ambient at stop lights.

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That’s the plan. I just added boostane to my tank to solve a little knock issue I noticed on high gear heavy load and it not only fixed, it improved it.

Now that my IAT2 hover in the 127-140 deg I hope the VMP keeps them at bay. Hoping of highest of 137 in traffic.


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luillo said:

Well, i'm 100% fixed. I had just about every cooling issue you could imagine but now i am an expert troubleshooting power/cooling issues.

Issues i found in sequence below:

CAC Pump relay bad> insane power loss after 20 minutes of driving the car. Not even second gear short shift squeal on the tires.

nGauge showed ECT up to 135 > Low speed fan not running at 208 target but runs on a/c activation. Jumped the relay pin 30 to 87 an nothing. Replaced fan resistor and fan runs on target.

Bonus- Thermostat broken inside housing> Replaced thermostat with Reische 170. When i took the old 192 out, the rear portion came off the thermostat.

So pretty much if your car is ruining hot, and i mean you can feel the heat coming through, check the fans, and ultimately thermostat. Jump the relay pins 30 to 87 on both high and low speed and if they run and the relays are clicking good, then all those components are ok and maybe is the thermostat.

If you have power loss on top of that and thermostat, fans, relays are good, check the CAC pump relay, jump pin 3 to 5 and cinch the bypass house, if the pump is flowing then you need an exorcist because i don't know what else could it be.

We can check voltage and proper continuity but i am old school and lack patience, so i jump and apply power directly as safe as i can to whatever i can and go from there.

Click to expand...

I’m having the same issue. Jumping high speed relay turns on the fan but nothing on the low fan speed relay. Did you replace the resistor to fix it??

Blitz1029 said:

I’m having the same issue. Jumping high speed relay turns on the fan but nothing on the low fan speed relay. Did you replace the resistor to fix it??

Click to expand...

Yeap. Replace the resistor in the fan and the problem will be solved. Also check the supercharger heat exchanger pump relay. that was blown on mine too but the overheating was due to the resistor.

It was the resistor. Thanks for the info and saved me a lot of time on trouble shooting. Good job on the follow up to let us all fellow mustang owners what resolved the issue. I've seen many threads with no follow ups.

always. it was easy to T-shoot so i like to share the info to support the hobby.

All the resistor is doing is providing a Vdrop, so the fan gets 9-11 vdc...instead of the full 14.75 vdc. ( current flowing through a resistor results in V drop of XXX Volts, depending on actual current drawn, and resistor value). IF ford had used a higher wattage resistor (of the same ohmic value), nobody would be burning the resistor open.

It's just a cheap and easy way to slow the fan down. Dunno what the exact value of the resistor is, but a bad one will show a wide open with any DVM. They never fail shorted.

With fan on high speed mode, the relay just shunts out the resistor. IF the resistor is burnt open, the low speed function will never work, only the high speed.

On my X3 that I bought from VMP (along with the tune) I can adjust BOTH the low and high temp thresholds...and each is adjustable over a huge range. In fact they overlap. IE: I can set the high speed fan threshold lower than the low speed fan threshold. (high speed threshold set as low as it will go..and low speed threshold set as high as it will go). Normally one would not set em like that, but it's doable. One application might be if you are on a road course. For road course applications, another option is to bypass the turn on relay, and feed 14.75 vdc directly to the fan..and let the fan run at max speed for the entire session, and perhaps a 170/180 F T stat.

I never heard of anyone running the fan on high all the time at a track day. General consensus is you need fans below 25mph, and above that, you have the ram air effect to cool the car. The funny thing is, I know my fan was coming on at the last track event. lol (for some reason, the Control pack strategy turns on the "lose gas cap" light when the fan comes on) I just don't think the fan running did a damn thing to cool the car at speed. It was a 90* day, and oil temp was a good 25* lower (260* vs 285*) with the Boss302 oil cooler I added.