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Coolant temp sensor issues

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Coolant temp sensor issues

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Old 06-19-2019, 10:02 AM
Dchilvers425
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Default Coolant temp sensor issues

So to start off with I do not have ohm reader but I have replaced my coolant temp sensor in my 98 ram 1500 318 truck and it still reading circuit high still. I have replaced the connector itself and referred to the Chilton book and made sure it was wired correctly, still no luck. But as I am looking at the book here I see that the signal wire which is black light blue is ran to the intake air temp sensor. So what I am wondering is is my air intake temp sensor bad causing my engine temp sensor to not work or am I missing something still
 
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Old 06-19-2019, 02:19 PM
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Really need a volt meter, and see what kind of voltage you are getting on the signal in wire. (should be tan w/black stripe.) Should only be 5 volts.
 
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Old 06-19-2019, 03:44 PM
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You are reading the wiring wrong way. Intake temp, oil pressure and coolant temp all share the same feed, signal to PCM is different color on all of them.
What brand sensor you bought? I bought a cheap coolant temp sensor, wasn't reading right. Next one was cost twice the cheap one, still wasn't as good as the original, but close enough.
But I suggest that you get multimeter, makes troubleshooting so much easier, and less guessing.
 
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Old 06-19-2019, 04:28 PM
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Originally Posted by HeikIlm View Post
You are reading the wiring wrong way. Intake temp, oil pressure and coolant temp all share the same feed, signal to PCM is different color on all of them.
What brand sensor you bought? I bought a cheap coolant temp sensor, wasn't reading right. Next one was cost twice the cheap one, still wasn't as good as the original, but close enough.
But I suggest that you get multimeter, makes troubleshooting so much easier, and less guessing.
I'm not 100% sure on the brand but I got it from napa auto parts and never had an issues till now with there sensors.. I tried to splice a new wire to the coolant temp sensor big mistake but got it back together and back to square one. So I guess another good question I think I have before I get a ohm meter type of deal, the book states that your are suppose to drain the coolant and also unhook the battery. I did NOT do those steps bought the book after having this issue of having a new sensor not work so did I somehow break the sensor by not taking these steps they recommended
 
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Old 06-19-2019, 04:52 PM
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Originally Posted by Dchilvers425 View Post
I'm not 100% sure on the brand but I got it from napa auto parts and never had an issues till now with there sensors.. I tried to splice a new wire to the coolant temp sensor big mistake but got it back together and back to square one. So I guess another good question I think I have before I get a ohm meter type of deal, the book states that your are suppose to drain the coolant and also unhook the battery. I did NOT do those steps bought the book after having this issue of having a new sensor not work so did I somehow break the sensor by not taking these steps they recommended
No you did not. What exactly are you experiencing?
 
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Old 06-19-2019, 05:02 PM
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So I put a new sensor in it as I had a circuit high to engine coolant temp sensor (p0118) code. I replaced the sensor and cleared the code and came right back. When the truck comes to operating temp from driving a bit the truck will want to stall out when first pressing on the gas. It smells like it is over fueling it self and also has a rough idle all the way around cold or hot
 
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Old 06-19-2019, 05:09 PM
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The temp sensor is EXTREMELY important in engine fueling. It is likely the sensor the ECM depends on the most, to give you accurate fuel metering. If it ain't workin', guess what? Nothing else does either. The sensor getting the wrong voltage, pretty much assures the truck isn't going to run right. So, you have problem. Either the sensor is getting the wrong voltage to begin with, or, the signal wire going back to the PCM is shorted to power from something else. If you have a scanner, you can plug in, and see what the pcm thinks engine temp is. Does that number seem reasonable?
 
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Old 06-19-2019, 05:20 PM
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I don't have that nice of a scanner to check that but all I'm getting is the p0118 code for high voltage engine coolant temp. But from what it sounds like get an ohm reader check that to see that sensor is bad or that I need a new engine harness
 
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Old 06-19-2019, 05:25 PM
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I'm going to throw another curve ball about the sensor I just remembered. When the the truck runs for awhile and you cycle the key (fully shutting off the truck) and turn the key back on they gauge will go up mid way to operating temp according to the gauge but after 5 min of running goes back to straight "cold" according to the sensor
 
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Old 06-19-2019, 07:21 PM
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Originally Posted by Dchilvers425 View Post
I'm going to throw another curve ball about the sensor I just remembered. When the the truck runs for awhile and you cycle the key (fully shutting off the truck) and turn the key back on they gauge will go up mid way to operating temp according to the gauge but after 5 min of running goes back to straight "cold" according to the sensor
Sounds like one of the wires going to the sensor is shorting out. Getting an ohm reader will help you. Harbor frieght has one for like 8 dollars
 

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