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Hello :D

At my last trackday in Monza I had problem with high differential temperature. (302 °F redline!!)1f480.png
Outside temperature on this trackday 86 °F.

This week we changed the differential fluid and yesterday did a little test on the German Autobahn.
-Outside temperature: 66 °F
-Speed driven: 75 - 124 mph
-Test duration: about 20min.

The differential temperature rose continuously! Even if I drove slower, the differential temperature hardly got lower.
At 217 °F I stopped the test. ForScan always showed "Diff Pump Off" during the whole test.1f644.png
The outside temperature was very cool compared to the track day and the speed was not really fast, but the differential temperature kept going up.
I don't think it should be like that.1f635.png

I can turn the pump on/off stationary (see video)
But I don't think it works properly when I drive.

-At what temperature does the differential pump turn on? (Shelby GT350)
-Is there anything I can check? Or is it possible that the pump is defective?
-Relay? Fuse?

Thanks for help1f60a.png

Bill Pemberton

0ld Ford Automotive Racing Terror
Exp. Type
Time Attack
Exp. Level
20+ Years
Blair, Nebraska
Hopefully someone will answer this soon, but I will try and catch my favorite mechanic at the Ford Dealership I used to work at to see if he can help. I am only concerned he may be on vacation as I could not contact him last week, but I will try .
@Bill Pemberton
that would be nice 🙂
here where I live, unfortunately no one has a clue about these cars 🥲
I had the same problem with my 2016, if you use Forscan you can turn the pump on and off, if you look at the schematic there is a separate line running to the pump for diagnostic testing.
When the pump runs normally it gets its signal from a different line in the ecu. I went to multiple Ford dealers none of the techs understood what I was talking about and said since the pump works when tested all is good unless there is a fault. So I then proceeded to make a fault by shorting out the temp sensor to send the gauge off the scale ,but no fault appeared so I knew there was a software issue that needed to be resolved. Again no dealer would look at the issue or give me time to explain the situation because no MIL faults. Having read many posts on this forum of diff temps on track I noticed many people were getting 230-240F and I was getting 260F on a cool day in one session.
I searched on this forum (sorry don't have the link) about adding an aftermarket pump and cooler to their car and I purchased the same pump, removed original pump , made a bracket, used the original power wires, hooked up an adjustable fan controller, JB welded the temp sensor provided to the case of the diff and I now have a working pump which I control when it turns on and my diff never gets over 220F now.
Sorry car is in storage so I don't have pics but I did this 5 years ago and still working.
My point is I believe there are many cars with some sort of software not working correctly related to the diff as I have seen people complain about high temps before.
Ford said if I left my car at the dealer for an undetermined amount of time they will get a tech in from Detroit and look into it. I was not going to do that so went the home made solution.
Hope this sheds some light.

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