Temp Sensor

Warthog

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Are you talking about the one on the read drivers side head?

That one keeps the GP from coming on when the engine is hot.

There are two styles. The older single pin style and the newer two pin style. If you go with the newer style you will also have to change out the electrical connector. Also be aware that there is a reducing bushing.

GM part# 10045847

Old style
Napa - TS4032
Orielly - WT5133

New style
Napa - TS4015
Oreilly - TS4052

new pigtail
Napa - TSC200
Oreilly - PT191

A fellow member just replaced his today

http://www.steelsoldiers.com/showthread.php?116069-Temp-sensor-replacing
 
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doghead

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I thought they were listed in the wiki and TM.
 

2deuce

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My truck was starting correctly, but now I don't get a wait light and no power to the glow plugs. I removed the connection to the temp sensor and I do get the wait light that stays on, but still no power to the glow plugs. I know the temp sensor tells the system to activate when cold and not when hot. Can someone explain how the system works electrically? I have ordered a new temp sensor and hope that is what is wrong. Thanks
 

2deuce

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I know the basic operation, but don't understand what is going on when something goes bad. Why does the wait light stay on with the temp sensor removed? I have another truck that has manual glow plugs and the wait light goes off on on randomly(GP card removed) as you're driving. Things like that I don't understand. When something isn't working right, it would seem there should be a certain cause and effect (with this glow plug system it is hard for me to figure out). That is what I look for, and eventually I replace the bad part.
 

antennaclimber

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I know the basic operation, but don't understand what is going on when something goes bad. Why does the wait light stay on with the temp sensor removed? I have another truck that has manual glow plugs and the wait light goes off on on randomly(GP card removed) as you're driving. Things like that I don't understand. When something isn't working right, it would seem there should be a certain cause and effect (with this glow plug system it is hard for me to figure out). That is what I look for, and eventually I replace the bad part.
The wait light stays on due to the fact that the GP card is not seeing any resistance from the sensor. When you disconnected the sensor you have created an "open" circuit. Opens are high in resistance.

The GP card is expecting to see a high resistance from a cold sensor and as the sensor temperature rises the resistance gets lower. This change of resistance (along with system voltage) is what determines if the wait light is to come on along with the other functions of the GP card.

The attached chart shows that as the sensor temperature increased the resistance decreases.
Karl
 

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2deuce

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Is it a good guess that the temp sensor is bad because the temp sensor is not showing any resistance when it is plugged in and the engine is cold? I will know tomorrow because will pick up the one I ordered from Napa.
 

antennaclimber

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Is it a good guess that the temp sensor is bad because the temp sensor is not showing any resistance when it is plugged in and the engine is cold? I will know tomorrow because will pick up the one I ordered from Napa.
Either the sensor is defective or the wiring is defective.
If your sensor has no resistance, that is the same as an open circuit. Thus the wait light will come on in a properly operating GP system.

I would test the sensor and the wiring separately to be sure that both are functioning correctly.

Also test the new sensor prior to installation to be sure that it is functioning properly. This may aid you in troubleshooting later on.


Karl
 

K9Vic

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Auto Zone sells this with the pig tail for under $20, much better over having to buy both parts. I just got one the other day to fix a friends M1009.

Duralast/Coolant Temperature Sensor
Part Number: SU102
 

2deuce

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antennaclimber, I think I know what you mean, but you said that no resistance = open circuit. If the circuit has no resistance as in closed circuit the wait light won't come on. High resistance the wait light will stay on.
 

milradioman

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Is the chart for the actual glow plug temp sensor or just Representative of a thermistor function? I suspect the sensor on my truck is the cause for the glow plugs to continue to turn on after the truck should be warm enough. I can hear the relay click on/off sometimes intermitant like a bad connection.
 

antennaclimber

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antennaclimber, I think I know what you mean, but you said that no resistance = open circuit. If the circuit has no resistance as in closed circuit the wait light won't come on. High resistance the wait light will stay on.
I see what you mean.

My interpretation:
No resistance = Open Circuit.

Zero to very low resistance = Proper circuit or short depending on what you are looking for.

If someone tells me that a resistor has no resistance, I take it as "open".

Karl
 

antennaclimber

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Is the chart for the actual glow plug temp sensor or just Representative of a thermistor function? I suspect the sensor on my truck is the cause for the glow plugs to continue to turn on after the truck should be warm enough. I can hear the relay click on/off sometimes intermitant like a bad connection.
The chart is the product of testing a new temperature sensor for the CUCV trucks. We measured the resistance of the actual sensor and plotted it to produce the graph.

Karl
 

2deuce

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Antennaclimber, It was in an earlier post you said open circuit=high resistance and that is also how I see it if there was a circuit, and no resistance to me means no drop in voltage, but I'm not very good with electrical problems. The new temp sensor gave me a a long wait light and the truck started so I believe the glow plugs were working as it is about 50 degrees here. It looks like my problem is solved, knock on wood. Thanks
 

ChrisC

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Just went to the local Auto Parts and they crossed the NAPA number to Borg Warner WT3000, which is the most common GM temp sensor on the shelf.
 
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