Fluid temp sensor/coolant temp sensor/oil temp sensor?

1692 Views 29 Replies 5 Participants Last post by Jeepman, 12 mo ago

AeroZ

Hello.

Was wondering which sensor is which and where are they located at?

First sensor:

The info in description is a bit confusing. I know it’s located at the oil filter housing. Is it a coolant sensor or oil temp sensor? If coolant temp sensor then where is the oil temp sensor located at?

Second sensor:

Description is once again a bit confusing which fluid’s temperature it reads. And what’s the location of it?

Thanks!

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Jeepman

· #2 · 12 mo ago

Engine oil cooler??
Coolant Temp Sensor - Mopar (05149077AB)
05149077AB - Ram Sensor. Coolant temperature, fluid | Myrtle Beach SC

Pictures show sensors and locations. Cylinder head??
Coolant Temp Sensor - Mopar (68164627AA)

68164627AA - Ram Sensor. Fluid temperature | Myrtle Beach SC

Genuine Ram Part # 68164627AA - Sensor. Fluid temperature. Ships from Myrtle Beach SC

www.moparpartsinc.com

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Cciman

· #3 · 12 mo ago

Besides sensing the temperature for the guages, do these have have any data input in the engine, or other component functions?

For example, does coolant temperature affect fan/ac switches, or oil temp input to pcm?

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Sienile

· #4 · 12 mo ago

Oil temp is derived from coolant temp at the oil cooler. Just the 2 coolant sensors and the oil pressure sensor for fluids.

Jeepman listed the correct positions, oil cooler and front head.

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Valhallalla

· #5 · 12 mo ago

The coolant temperature sensor (ECT) is a very important input to the PCM. It is used to calculate fuel mixture, ignition timing, whether the engine should be run in open or closed feedback loop and the operation of the cooling fans among other things. Chrysler uses a pressure/density system for its electronic fuel injection. The temperature of the engine greatly affects the density of the air/fuel charge. An ECT that is out of calibration can affect the EFI operation significantly. The use of data from the ECT for the temp gauge is merely a convenient secondary function.

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AeroZ

Discussion Starter · #6 · 12 mo ago

Sienile said:
Oil temp is derived from coolant temp at the oil cooler. Just the 2 coolant sensors and the oil pressure sensor for fluids.

Jeepman listed the correct positions, oil cooler and front head.

Do you know how do they derive oil temp from the coolant temp?
Do you also happen to know which sensor’s reading is coolant temp gauge and EVIC’s coolant temp showing?

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Cciman

· #7 · 12 mo ago

Is the ECT the one on the head? Thanks for the info.

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AeroZ

Discussion Starter · #8 · 12 mo ago

Valhallalla said:
The coolant temperature sensor (ECT) is a very important input to the PCM. It is used to calculate fuel mixture, ignition timing, whether the engine should be run in open or closed feedback loop and the operation of the cooling fans among other things. Chrysler uses a pressure/density system for its electronic fuel injection. The temperature of the engine greatly affects the density of the air/fuel charge. An ECT that is out of calibration can affect the EFI operation significantly. The use of data from the ECT for the temp gauge is merely a convenient secondary function.

Which one is the ECT? The one in oil filter housing or the other?

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Valhallalla

· #9 · 12 mo ago

AeroZ said:
Which one is the ECT? The one in oil filter housing or the other?

I can't tell you for certain. I didn't even know that there were two sensors on these vans until a little while ago

I have a 4th gen and am not very familiar with 5th gen vans, just speaking from my general Chrysler knowledge. If I were to guess I would say the one in the cylinder head is the primary coolant temp sensor.

What are you trying to fix on your van?

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AeroZ

Discussion Starter · #10 · 12 mo ago

Valhallalla said:
I can't tell you for certain. I didn't even know that there were two sensors on these vans until a little while ago I have a 4th gen and am not very familiar with 5th gen vans, just speaking from my general Chrysler knowledge. If I were to guess I would say the one in the cylinder head is the primary coolant temp sensor.

What are you trying to fix on your van?

Not fixing anything. Just researching, learning and educating myself.

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Cciman

· #11 · 12 mo ago

Where's the sensor(s) for the radiator fan?

Why and how is the AC tied to the cooling system?

I'm trying to learn too.

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Jeepman

· #12 · 12 mo ago

Cciman said:
Where's the sensor(s) for the radiator fan?

Why and how is the AC tied to the cooling system?

I'm trying to learn too.

The computer tells the fans what to do.

There is a fan relay down in the area of the radiator.

https://www.carparts.com/blog/bad-cooling-fan-relay-symptoms/#:~:text=to%20the%20fan.-,What%20Does%20a%20Cooling%20Fan%20Relay%20Do%3F,when%20the%20vehicle%20is%20immobile

When the engine temperature approaches unsafe levels, the vehicle’s computer or temperature switch turns on the cooling fan relay. The activated relay completes a circuit, allowing an electric current to flow through it and reach the cooling fans.

HOW DOES AN ENGINE COOLANT TEMPERATURE SENSOR WORK?

How Does an Engine Coolant Temperature Sensor Work? - Meineke

Your car’s temperature sensor safeguards against overheating - but how does it work? Learn all about an engine temperature sensor with Meineke.

resource-center.meineke.com

On most vehicles, the coolant temperature sensor (CTS) can be found somewhere near the engine thermostat, which allows it to function optimally. The tip of the CTS is probably located right next to the engine coolant.

The sensor works by measuring the temperature that’s being given off by the thermostat and/or the coolant itself. The temperature is then sent to the on-board control system. From there, your vehicle’s computer will use this temperature information to either continue operating or adjust certain engine functions, always working to keep the engine temperature at an ideal level.

Many cars use an A/C pressure switch which, as well as a maximum/minimum cutoff, will turn on the cooling fan if the system pressure rises above a set point. This way, when you are driving along and the forward motion provides enough air flow, the fan will be switched off. If you are stationary and the pressure rises, the fan will activate to increase the cooling air flow and control the pressure.

Other cars simply run the fan whenever the A/C is on.

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Cciman

· #13 · 12 mo ago

Above is Too generic unless it applies to gen5 TC.

How does the pentastar do it? What sensors and where are they? Lots of posts about engine temps, fan speeds, and AC coming on off

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Jeepman

· #14 · 12 mo ago

The Pentastar is pretty generic across the Chrysler lineup. The pictures referenced in Post #2 list the various sensors and where they are located.
I have a Haynes Manual on order, specific to the 5th Generation, there may be more there. The differences between the T&C and Dodge Grand Caravan are mostly cosmetic.

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Sienile

· #15 · 12 mo ago

I'm pretty sure the head ECT is for the gauge and fan. The one on the oil cooler is in a coolant passage surrounded by oil, so it gets a pretty close idea of what the oil is, but it's not as exact as one that measures the oil directly.

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Jeepman

· #16 · 12 mo ago

Oil pump output is computer controlled using the sensor inputs for oil and coolant temperatures and other inputs.

The Powertrain Control Module (PCM) switches the pump between stages based on engine operating conditions, oil and coolant temperatures, speed and load. Under most typical conditions, the pump will run in low mode from idle up to around 3,000 RPM, and switch from low to high mode between 3,000 and 4,000 RPM.

Pump … You Up! | Mopar Magazine

www.moparmagazine.com

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Cciman

· #17 · 12 mo ago

How is the radiator fan controlled to come on/off, and then high or low speed?

Is it directly from ECT, or from pcm sending control input to the fan?

What causes AC to stop that is related to the cooling system?

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Valhallalla

· #18 · 12 mo ago

Valhallalla said:
Chrysler uses a pressure/density system for its electronic fuel injection.

Doh! 😮 Chrysler doesn't use a pressure/density EFI system which would be redundant. It uses a speed/density system to determine how much air is entering the engine. Not sure where my head was at with that statement.

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Valhallalla

· #19 · 12 mo ago

Cciman said:
How is the radiator fan controlled to come on/off, and then high or low speed?

Is it directly from ECT, or from pcm sending control input to the fan?

What causes AC to stop that is related to the cooling system?

This is the fan operation chart for a 4th gen van. The 5th gen chart is similar if not the same. Somebody posted it recently in another thread. The fan operation is ultimately controlled by the PCM based upon inputs of the ECT sensor, A/C pressure sensor and trans oil temp.

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Sienile

· #20 · 12 mo ago

5th gen fan chart, yep, all values are the same.

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