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Engine Coolant Temp Sensor Options

Discussion in 'Minivans · Pacifica' started by TaxiGirl, Apr 20, 2017 at 11:42 AM.

  1. Doug D

    Doug D Virginia Gentleman

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    I have no idea if that is too high or too low or normal? What oil temperatures have you observed in the past? Considering the optimal engine temperature is around 200 F this sounds like it may be okay.
     
  2. AllanC

    AllanC Active Member

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    This points to an extreme heat load generated through the transmission. Stop and go driving with lots of upshifting and downshifting of gear ratios in the transmission will generate a lot of heat. The 4Xte and 6Xte transaxle shifting logic tended to allow more slippage and thus generated more heat on the transmission. This gets passed along to the engine cooling system.

    I remember in a previous post that it appeared the automatic transaxle was overfilled. Too much fluid in the transmission can cause excessive heat generation. Did you get the fluid level set correctly?

    The radiator fan speed selection is controlled by the TIPM and the PCM. If engine coolant temperature is above a certain threshold and / or the A C compressor is engaged, the PCM sends a signal to the TIPM for cooling fan operation. The TIPM determines criteria and then engages either the low speed fan relay or the high speed fan relay. Are you getting a CHECK ENGINE lamp symbol along with diagnostic codes P0480 and P0481?

    Here is a schematic of the radiator fan control circuit and load circuit. There is only 1 radiator fan with 2 control inputs. The TIPM controls both the low speed and high speed through separate relays. When the low speed fan relay is engaged 12 volts is passed through a resistor circuit that drops the voltage to the fan motor. The motor runs at reduced speed.

    Radiator Fan Circuit Control.GIF

    When more air flow is needed through the A C condenser and radiator for greater cooling the TIPM engages the high speed relay. A full 12 volts is applied to the fan motor. At this point it does not matter if the low speed relay remains engaged or not. The 12 volts is higher voltage and overshadows so to speak the lower voltage so the fan motor immediately runs at its maximum designed speed.
     
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  3. AllanC

    AllanC Active Member

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    I really don't think the additive is causing a problem of overheating or excessive wear due to viscosity. The only accurate and scientific way to determine engine wear is to send a sample of the engine oil at drain time to a specialized lab. Excessive bearing wear (caused by too thin / low viscosity oil) will appear as excessive traces of bearing metal in the oil.

    You are within the safe limits of engine oil temperature. In fact oil temperature should be higher so as to evaporate moisture and other liquid condensate contaminants from the oil. I would typically expect engine oil temperature to be slightly below coolant temperature.
     
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  4. TaxiGirl

    TaxiGirl Member

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    no check engine light and when i stopped a little ago i pulled out the dipstick to see if it felt hot and it did not seem that hot. but now i have been monitoring the oil temp and psi. when driving above 60 oil temp is 199 and psi is 37 psi. when stop at redlight oil temp stays same and oil psi drops to 20psi. i am on my way to buy oiil. but, what else should i do
     
  5. TaxiGirl

    TaxiGirl Member

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    does a radiator psi test check for bsf radiator or just for leaks. there are too many unknows right now i do not know what to do
     
  6. TaxiGirl

    TaxiGirl Member

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  7. TaxiGirl

    TaxiGirl Member

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    tranny level correct now. i am at a loss.
     
  8. TaxiGirl

    TaxiGirl Member

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    All of the other diagrams show the high speed relay out side the TIPM If it is inside then what relay is it> Because K11 is the low speed?
     
  9. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES" Level 2 Supporter

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    I would expect 12V, not 4.9V. Regardless, if you get the same voltage on both sides of a relay coil, it is not being energized, and therefore the relay is not closing. The PCM switches the low side of the coil to ground (zero volts) to energize the coil and close the relay, so this shows that the relay is not being switched, and I would not suspect the relay or fan as being bad. Either a sensor is not telling the PCM to close it, or the PCM is not switching the coil, or a connector or wire is bad somewhere.
     
  10. TaxiGirl

    TaxiGirl Member

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    I did get 12 v on 87 and 30 but, most of the time control signals are at a lesser amount from computers, I THOUGHT. I do not know what the control voltages (signals) are that are sent from the computer data lines., I checked with a test light with reference to chassis ground all pins for the K11 relay light came on for 87 and 30 but neither light for the other 2 pins. I have the schematic that Doug posted but, I had thought prior to this that the relay behind headlight was for the high speed. I do not know what relay is for the high speed if it is inside the TIPM
     
  11. TaxiGirl

    TaxiGirl Member

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    View: https://youtu.be/D0D0xu-wG14

    PLEASE SEE LINK I do not know what these references are on this schematic N23, so forth
    the send relay that I marked high speed I thought was the hi speed the low speed is in the TIPM K11, IDK what the other relay is in the other pic
     
  12. AllanC

    AllanC Active Member

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    I will post the reference schematic to the radiator control circuitry. I have added some notes of explanation. N23 is a manufacturer circuit identification. It can be disregarded with your testing.

    Radiator Fan Circuit Control 2.gif

    Previously I had indicated that the high speed fan relay should be found in the TIPM along with the low speed relay. I have researched some more and that was a false statement. My apology for misleading you. I believe the relay you identified near the headlamp is probably the high speed relay. You can check the 4 wire colors from the schematic and that should help identify it.

    This is a chart that explains the operation of the radiator cooling fan. There are 3 inputs to the PCM and TIPM that are used to determine fan operation and fan speed: engine coolant temperature, A C system pressure (discharge), and transmission fluid temperature.

    Fan Operation Chart 2.GIF

    In recent postings, you indicated that engine coolant temperature reached 230 deg F and you thought the engine was overheating and shut down the A C system. Did the engine temperature peak at 230 deg F and slowly drop or did it continue to rise?
     
    Last edited: Apr 21, 2017 at 9:34 PM
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  13. TaxiGirl

    TaxiGirl Member

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    Thank you Allan for following up. No worries. Last night, I figured it out after reading this post in another forum

    Inside the Pentstar cooling fan - JKowners.com : Jeep Wrangler JK Forum (at http://www.jkowners.com/forum/stock-jk-tech-dept/270930-inside-pentstar-cooling-fan.html )

    I had suspected the Aftermarket Cooling fan Murray that I got at Oreilys and the 2nd stage low speed was not working because the thermistor iss wound with fewer rounds and it burns out. Even when I put on the thermistor from the OEM fan the low speed still did not work. . Also, the thermostat had a pin hole leak from the bleed screw, Between last night and this morning,, I replaced the thermostat and I reinstalled the OEM fan and now the fan does work with low and high speed and it cycles on when it is supposed to and the thermostat opens and closes correctly. I let it run with the ac in the driveway for half hour. It seems to be working great. I am not real happy with the POS fan that I got at Oreilys that is supposed to be a direct replacement. Thank you so much for all of your help. PLEASE ANYONE READING THIS, DO NOT USE A AFTERMARKET FAN TO REPLACE YOUR OEM FAN, YOU WILL HAVE THESE SAME ISSUES.
     
  14. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES" Level 2 Supporter

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    Thermistors usually do not have wound elements. And that would not inherently cause a failure.
     
  15. TaxiGirl

    TaxiGirl Member

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    I compared the two wire would green things that are on each fan, each fan has a green thing that is wire wound and another hidden probably thermistor,so that one is not allowed to see the value. The green wire wound thing on the OEM is wound more times and it covers more of the surface area of what each the thing is.