My OD light is flashing. Shop ran scan tool; code came up as "transmission fluid temperature sensor". The voltage gave a wide range of readings and temperature went between 0 - 50 degrees. Sensor pack at Ford dealer runs $430, but found on-line for $155. Read on-line that sensor packs rarely go bad. Is there any truth to that info? I am used to doing my own maintenance and repairs. Diagram from Ford dealer not very clear. Looks like sensor pack is located in transmission by filter. Can't tell if it's easy to get to. Any input would be greatly appreciated.

Bronco has never seen snow or salt. Kinda bummed - having to use it in the Minnesota winter for the very first time.

 

Sounds like the fluid is not getting warmed up, but I'm only guessing.

My 1999 Ranger doesn't register an oil pressure for 4 minutes when I start it in the morning, that's a minus 20 degrees morning. Ford reccommends replacing the sender
I decided to wait 4 minutes.

 

You almost answered your own question. If you are concerned that the readings from the sensors are inaccurate, probe the temp of the fluid while she's running or have someone do it. If you are more convinced that the sensors that rarely fail are bad, then spend the money and find out after all that money that the fluid is really getting hotter than it should and flush and refill the fluid.

 

I drove about 15 miles before the scan was done. While scanner was plugged in the temp showed a reading of 0 thur 50 for temp. The voltage reading went up and down never stayed at one reading.The Bronco was at normal operating temp. I have 47000 miles on truck so it would be good time to change fluid anyway. I should of wrote down the codes.

 

Sorry, I just re-read my last post and that really sounded snotty. I personally have had terrible luck with the E4OD and don't like it to begin with so that probably biased my response.

I would be absolutely certain that the fluid is indeed getting too hot before assuming the sensor(s) are bad. Old fluid will not maintain viscosity if it gets too warm which causes all sorts of issues in a hydraulic system. Although 50 degrees doesn't seem too bad unless that is a Celsius reading.

 

I'm kinda curious, you said that your voltage readings also fluctuated a lot and your TOT sensor reading also fluctuated between 0-50 deg (C) ? The voltage reading is the system voltage and is not controlled by the PCM or any outputs from the TOT sensor in the tranny. I think you have a problem elsewhere. If your tranny temp was very hot, it could be related to the famous (in) converter slippage issue common to the earlier E4OD's. I think you said that it did all this very early after cranking, so I tend to rule out overheating of the tranny fluid. What year is your vehicle?

 

How did I miss that part... going blind... but enough about my personal issues...

Seeing a zero reading on the system voltage could not possibly be correct unless there is a fault in the wiring or some connection to the scanner. (Obviously if the electrical system voltage went to zero while the truck was running it would no longer stay running). The question then is,"Where does the scanner take the system voltage reading?" Does it take it at pin 1 of the PCM or somewhere further up the line? Benshere, I assume you know this scan procedure so I suppose this question is directed to you.

System voltage (battery/alternator voltage) should not fluctuate much at all but if it does, it can adversely affect VREF (reference voltage) which will throw every sensor in the truck out of whack including the sensor in question. Lose enough input voltage to the VREF power supply and the VREF signal has no choice but to drop. If the system voltage is allowing fluctuation of VREF then every sensor in the truck should be adversely affected by it. This won't necessarily cause issues elsewhere as long as the return information from other sensors to the PCM is "within established parameters". The "established parameters" for the sensors in the E4OD are fairly tight though. VREF power is +5VDC approx. Test by taking a voltage reading between pins 26 and 46 of the PCM with the computer connected, the key ON and the engine OFF. The voltage should be constant. Test again with the engine running to see if the problem manifests itself while the truck is running.

 

Hold that thought Greystreak Just happened to get up and see that I left this monster powered up---dont like to do that!

I will have to dig out that EVTM tomorrow (when I can once again see) Sounds to me like you got er figured. I dont like the idea of the system voltage fluctuating----I kinda doubt it really is. Will attempt to resume thinking again----tomorrow

 

The shop hooked up the tester to plug inside cab. If that info helps. My bronco is a 1996 EB with tow pack if that makes a differance. I sure like the old stuff I`m used to working on. I drive semi over night so it would be this weekend before I can look into it. If I could get some ideas of wear to start or what to look for. The temp is what gave the 0 to 50 F reading. The voltage was all over the place. Thanks for your time trying to help with info.