QuestionQUESTION: Roland, the 8th spot in the vin is a P. But this sensor is at the front of the motor next to 2 hoses, one radiator and one smaller hose. It points out to the right(drivers side). Looks like this; http://www.theautopartsshop.com/search/LargeImage.aspx?imgPath=DE/TS10019.jpg
Where can I find schematics for this truck?
ANSWER: On the schematics, perhaps Alldata.com has them. On the question of the sensor, I would believe that is indeed the coolant temp sensor, and that it should show a resistance across its terminals of about 4,000 ohms at 70F, and that it then decreases smoothly as the temp of the coolant goes up and reaches about 700-1,000 ohm when the engine is at operating temperature. Measure the resistance after removing the plug for the sensor. The fan may come on as the result of pulling its plug, so that is normal.
Roland
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QUESTION: So you're saying; set the meter @ 20k ohms, attach the meter leads to each prong in the sensor housing and the meter should read 4000 Ohms, then with the prongs STILL on the sensor prongs (there is only 2 prongs, sound correct?) start the engine and let the truck warm up and then the reading should go down to 700-1000 ohms. Is this all correct?
Now if it doesn't go down to 700-1000 ohms, the sensor is bad?
Thanks
AnswerThat is correct, but I would first measure the resistance when the engine is cold, then reconnect the plug and let the engine warm up somewhat. Then turn off the engine and measure the resistance again. Then re-connect the plug and warm the engine up to operating temperature. Then turn off the engine, remove the plug, and make a final resistance measurement.
I suggest that you allow the engine to warm up with the sensor plugged in so that its input is available for the engine to know what is going on with the coolant temperature.
Roland
