ECT diagnosis and high temperatures.

Discussion in 'Gen 1 & 2 - Emergency Issues - Help & Maintenance' started by tracy_s_1993_atx, Jul 21, 2019.

  1. tracy_s_1993_atx

    tracy_s_1993_atx SHO Member

    Joined:
    May 31, 2003
    Messages:
    97
    Likes Received:
    8
    Location:
    Plano, Texas
    Home Page:
    Greetings,
    My 1993 SHO ATX has been running a little hotter than normal. I installed a manual temperature gauge and the temperatures are as follows:

    Engine Idling:
    224F -> Fans run at low speed.
    218 F-> Fans turn off

    Engine Idling A/C running:
    Fans run and the temperature stays at 191F with an ambient temperature of 98F.

    The Fans do work at high speed when I pull the codes. No codes set!

    I purchased a breakout box to try and diagnose the problem.

    Battery disconnected and ECU disconnected with breakout box installed
    Test Pin 46 to ECT -> 0.0 Ohms
    Test Pin 7 to ECT -> 0.0 Ohms

    So I know the wiring to the sensor is good.

    Now I connected the ECU to the breakout box and ran the engine.
    Test Pin 20(case ground) to Test Pin 26(VREF) -> 5.17 volts

    Test Pin 20(case ground) to Test Pin 7(ECT) -> 0.618 volts when fans turn on low speed.
    Test Pin 20(case ground) to Test Pin 13(Low Fan control) -> 13.7 volts Fan on
    Test Pin 20(case ground) to Test Pin 31(High Fan Control) -> 0.0 volts

    Test Pin 20(case ground) to Test Pin 7(ECT) -> 0.655 volts when fans turn off.
    Test Pin 20(case ground) to Test Pin 13(Low fan control) - > 0.0 volts
    Test Pin 20(case ground) to Test Pin 31(High Fan control) -> 0.0 volts

    What voltage should I see on Test Pin 46 (Signal Return)?
    That Test Pin seems to be shared with many other sensors i.e. O2 Sensors, ECT, Ocatne Adjust, Power Steering Pressure switch, Throttle Position Sensor, Knock Sensor, Intake Air Temp. Sensor an the DPFE sensor(EGR).

    I am wondering if the ECT sensor(new) I am using is not properly calibrated for our SHO's?
    I have the service manual and I have a chart for temperature vs resistance. And temperature vs voltage.
    I will probably pull the ECT and test in a hot pot of water and test the resistance as the temperature changes.

    Which ECT sensors are the SHO owners on this forum using? I think that I have the Standard Motor Products TX6. I would like to find a OEM motorcraft ECT, but that does not look to be available.

    I tried with a different ECU and CCRM and get the same results.

    Suggestions?

    Thanks in advance,
    Michael
     
  2. luigisho

    luigisho SHO Member

    Joined:
    Nov 2, 2001
    Messages:
    8,570
    Likes Received:
    1,614
    Location:
    va beach,va
    Home Page:
  3. tracy_s_1993_atx

    tracy_s_1993_atx SHO Member

    Joined:
    May 31, 2003
    Messages:
    97
    Likes Received:
    8
    Location:
    Plano, Texas
    Home Page:
    I am looking at local parts stores. I guess that I could just get one from Ebay and check that one as well.

    Thanks for the link.

    Michael
     
  4. NoSlo

    NoSlo GoldMember

    Joined:
    Aug 21, 2003
    Messages:
    650
    Likes Received:
    430
    Location:
    Portland, OR
    Home Page:
    Measurements at the sensor. Resistance is with the harness unplugged.

    [​IMG]

    Voltage is the return wire. Pin 7, LG/R at the ECU. The other sensor wire is 5V reference. The voltage reference is used by several sensors, such as TPS, and reference voltage should be 5V. Voltages in the temperature table, +/- 15%.

    You can measure with the sensor installed and engine running. Jam a multimeter probe into the back of the sensor connector, and ground the other. If you get 5 volts, it's the other sensor wire. Measure temperature reading of the outlet housings and compare.

    From my "cooling fan rebuild howto":

    Your car's cooling fan, or dual fans, have two speeds. It should turn on low when the car's temperature is measured at 215 F, and should switch to high if it reaches 230F. It will switch back to low or off once these temperatures have been lowered by a few degrees.

    With the A/C on, the fan(s) will run continuously, unless the car is going over 45 MPH and the coolant temperature is below 220F.

    The turn-on temperatures and voltage would be better measured with an infrared thermometer pointed at the water outlet housings.

    The temperature sensor is standard for almost every Ford for decades.
     
    Last edited: Jul 28, 2019
  5. tracy_s_1993_atx

    tracy_s_1993_atx SHO Member

    Joined:
    May 31, 2003
    Messages:
    97
    Likes Received:
    8
    Location:
    Plano, Texas
    Home Page:
    I have purchased a few Sensors from the local chain stores:
    Duralast SU201
    Standard Motor Products TX6
    Master-Pro 2-9362
    Napa MPE TS4060SB

    I tested each with a pot of water slowly heating using two thermometers for temperature readings and my Fluke DVM to check the resistance.

    The Napa ECT sensor closely follows the Specifications from the Ford Service Manual.

    The Duralast ECT was the worst, followed by the Master Pro, the STD TX6 and then the Napa brand.

    I am going to replace my ECT with the sensor from Napa and test again on my SHO. I plan to get a Ford sensor either from Ebay or directly from Ford and then do the stove top testing as well.

    I did use an infrared thermometer to validate the manual gauge that I have installed.
     
    NoSlo likes this.
  6. NoSlo

    NoSlo GoldMember

    Joined:
    Aug 21, 2003
    Messages:
    650
    Likes Received:
    430
    Location:
    Portland, OR
    Home Page:
    You run out of steam at the boiling point of water...

    I was thinking instead you could drill and tap threads into the end of a cast 20lb dumbbell, like I crank out reps on. Perhaps fill the void with oil or straight coolant, and score the tapped threads so liquid pressure can escape. Screw the sensor(s) into the weight. Shield the probe wires from heat. Put the dumbbell on a hot plate, or apply a propane torch to the handle side of the dumbbell weight. There would be plenty of mass to moderate the temperature, and the sensor would measure like it does in the car. Heat up to 240F, and plot the resistance curve as it cools, as you also monitor with an infrared thermometer (or thermocouple on your dual-trace recording instrument).

    The table of values indicates that the ECU has an internal voltage divider with a ~20.5 ohm resistor. The tolerance of this resistor and how it is affected by heat will affect the ADC measurement of the sensor resistance, therefore it is best to confirm not just that the sensor resistance is in spec, but confirm the voltage in-car is in spec.
     
    Last edited: Jul 21, 2019
  7. SHOMON

    SHOMON 95 MTX Supporting Member

    Joined:
    Aug 15, 2006
    Messages:
    544
    Likes Received:
    64
    Gender:
    Male
    Location:
    MEDWAY MASS.
    It looks like the sensor DY-681 has superseded to DY-1145. It has a different connector but comes with the replacement pigtail. $25.79 on RockAuto.
     
    luigisho likes this.
  8. tracy_s_1993_atx

    tracy_s_1993_atx SHO Member

    Joined:
    May 31, 2003
    Messages:
    97
    Likes Received:
    8
    Location:
    Plano, Texas
    Home Page:
    I ordered the Ford 9U2Z-12A648-A - SENDER ASY and will test and graph the results against the Service manual.
     
  9. tracy_s_1993_atx

    tracy_s_1993_atx SHO Member

    Joined:
    May 31, 2003
    Messages:
    97
    Likes Received:
    8
    Location:
    Plano, Texas
    Home Page:
    Well an update. I installed the NAPA ECT and the fans turn on at 215F and off at 210F just like the manual states.

    No more garbage sensors from AutoZone(Duralast) or Oriellyauto(Master Pro) for me. From now on it is NAPA brand or OEM. I have been fighting this issue way too long.

    Very frustrated
    :cussing:
     
    luigisho and NoSlo like this.
  10. NoSlo

    NoSlo GoldMember

    Joined:
    Aug 21, 2003
    Messages:
    650
    Likes Received:
    430
    Location:
    Portland, OR
    Home Page:
    Could also just be luck of the draw, allowable manufacturing tolerances, unless the parts counter wants to let you test their entire stock for consistency.
     
  11. tracy_s_1993_atx

    tracy_s_1993_atx SHO Member

    Joined:
    May 31, 2003
    Messages:
    97
    Likes Received:
    8
    Location:
    Plano, Texas
    Home Page:
    You might laugh, but I have asked the counter person for all of their stock before to be able to compare. I was looking for some Timken bearings that were not made in China. They had a mix of USA, China, Mexico and Poland.
     
    luigisho and SHOMON like this.

Share This Page

If you wish to help keep SHOforum running, please click the donation button below