I have a `95 Explorer with the electronic four speed automatic transmission. Over the last nine months the O/D light start flashing indicating a fault code. I reset it by disconnecting the battery without bothering to read the codes. That stopped for severa months but now has started it again. This time I read the codes and I’m getting code 636 and 637 - both dealing with trans temp sensor not reading correctly.

Does anyone have any experience with this issue on this trans? Is it just a bad sensor? Does anyone know where the temp sensor is located? It is not shown in the Haynes manual as far as I can tell.

Thanks in advance for any help,

Mark

 

I'd take a look at the wiring to the sensor & if it looks good replace the sensor.

My guess would be that the sensor is in one of the coolant lines or mounted to the trans near a cooling line.

 

Thanks 87 XLT. I had the same thought about where it might be located, but was hoping that someone may have had a similar experince and could shed some additional light on the whole issue. Plus, I am hoping that the sensor is not inside the transmission.

Mark

 

I just checked with my local dealer and they could not find a trans temp sensor on my `95 Explorer. They said there is a range sensor and that it is in fact a multi-function sensor to include neutral safety switch. They said the temp sensor could be included in it. Can anyone confirm this?

Thanks,

Mark

 

The wiring diagram in my Ford "electrical & vacuum troubleshooting manual" for the auto trans in my wifes 95 Taurus shows that it does have a trans coolant sensor. I would think that yours would also have the silly thing.

Take a look at the wiring diagram in your Haynes.

 

BTW heres what the EVTM sez about the temp sensor. "The PCM uses this info to determine transmission fluid temperature for adjustment of shift schedules and torque convertor engagement schedules when the fluid is cold."

Haynes does'nt have the best wiring diagrams, but look for the section that shows the wiring between the trans & PCM.

 

All the range sensor does is tell the power train control module/PCM which gear you have selected.

"The PCM monitors the voltage from the range sensor which coresponds to position of the transmission lever."

It also acts as the backup light switch & as you say neutral safety switch.

 

I have checked the Haynes wiring diagram and can not find anything identifying a trans temp sensor.

I also called a second Ford dealer and the parts guy also said the same thing that there wasn't one showing. When I question how the fault code could be stating it was the problem if the truck didn't even have one he said he would look into it for me. He called back and said that his transmission mechanic said there wasn't a temp sensor on a `95 Explorer.

There seems to be very differnt information on this issue. Hopefully someone can point us to where it is acually located.

Many thanks,

Mark

 

Sounds like the only thing left to do is poke around underneath & see if you can find a broken wire.

Dont know if this will matter but heres the sentence I left out above: The PCM monitors the voltage drop across a temperature sensitive thermistor. The PCM uses this information.........

Good luck with it.

Now, if I could only convince my dear "I just want to put it in "D" & go" wife to drive a manual trans, I would never have to deal with this sort of nonsense on her cars. But she's worth it.

 

I have now spent more time going through my Haynes manual. It shows the trans temp sensor to be a TFT (transmission fluid temperature). In a diagram of where various sensors are located within the vehicle, for the TFT it simply points to the trans (I guess it could be inside the trans) and it states that the TFT is part of the transmission wiring harness. Therefore, it does not sound like there is a separate sensor as there is for speed or range.

Does anyone know how to fix this?

Mark

 

After the dealer could not find the TFT I called a trans shop locally that I have used before. They knew exactly what I was talking about and said that the wiring is part of the solenoid wiring, internal, and was relatively easy to replace once the pan was down. The insulation starts to crack with age and that causes the problem.

I then went back to the dealer and he was able to find the internal wiring harness and included in the description it states that it includes the TFT. I am going to have a regular trans service and have it installed at that time. The wiring harness is $115.

Mark