1998 Mustang GT - Transmission throwing po713 "Trans temp sensor high input"

thebullfrog

New Member
Mar 17, 2018
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Hi all! First post because of a mystery issue I can't wrap my head around.
So my 98 GT Auto. started flashing the O/D light the other day. The code is Po713 - "Transmission temperature sensor high input"
Thing is, there is no trans temp sensor in a 98 Mustang GT. Its working fine, fluid is fine, no matter how many times I clear the code, it keeps coming back.
Last year it threw a code for "4x4 Low range switch failure" which obviously also makes zero sense. Never came back after I cleared it.
So, any idea WTF I need to do to fix a sensor that doesn't even exist? I found a thread elsewhere for the same thing in I think a '97 back in 2007. No explanation/fix was ever posted.
 
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The 1998 GT auto does have a TFT temperature sensor. It's on the pin #2(GY/R and #5(O/BK) wires.

>>From Ford manual
P0713 TFT, Wiring, PCM -40°C (-40°F) indicated TFT sensor circuit open. Voltage drop across TFT sensor exceeds scale set for temperature -40°C (-40°F) Firm shift feel. Refer to Pinpoint Test B .
 
Consider the TFT sensor may be part of the circuit board inside the transmission.

Or the problem is in the wiring harness or even the connector.

Do you have a Ford service manual and wiring diagrams? If interested in getting a copy for yourself I maybe able to help. PM if interested.
 
I don't, but I really don't understand how it is I can't find any reference to the thing existing or its location anywhere. With the millions of cars on the road with this trans, I'm the first person to have this CEL? I feel like it shouldn't be this hard to look up what I need to replace (assuming, obviously it isn't a wiring issue in the harness)
 
OK, post on a Crown Vic forum says 98+ it's integrated into the harness (somehow? no explanation) but of course that's on a Crown Vic, who knows what kinds of minor things Ford tweaked between the cars. I've never had such a hard time finding such basic info for any car before *sigh*, I might have to make a couple phone calls to get hold of an old family friend who was a Ford tech for decades.
 
"Do you have a Ford service manual and wiring diagrams? If interested in getting a copy for yourself I maybe able to help. PM if interested."

Best thing you can do, now and for the future.