Tacoma temperature gauge

I own a 2003 Toyota Tacoma, and over the past few days the temperature gauge has been working only intermittently. At first I though I might be low on coolant, but things run well, and the check engine light has not come on. Since, it reads as a normal temperature when it does work, I assume the engine temperature is normal. So I am assuming that it either the temperature senser or the sending unit. They look like easy to install parts, but where in this engine might I find them? Does my diagnosis sound correct, or are there other things that I should look at?

Thank You

First make sure the radiator is full of coolant. Checking the overflow bottle isn’t enough. Then make sure the engine is warming up to correct operating temperature. You can’t go by the gauge for this. You need to measure the actual temperature of the coolant.

Maybe the gauge is working correctly and the thermostat is faulty. When you say the gauge doesn’t work, what, exactly, do you mean? Does it read low, or high, or not at all?

The gauge reads either not at all or normal, usually not at all, and when it does read, it erratically bounces between normal and not at all.

Check the electrical connection at the sender. It should be located very close to the thermostat.

I will give that a try, but it will probably not be till tomorrow, as I am working now. Thank you for your help.

This is what the engine temperature sensor look like. You will only see the electric plug and the brass colored nut. The electric plug may, or may not, be white. http://www.autozone.com/autozone/catalog/parts/partsProduct.jsp?itemIdentifier=61401_0_0_&skuDescription=Duralast+/+Coolant+Temperature+Sensor&brandName=Duralast&displayName=Coolant+Temperature+Sensor&categoryNValue=15299999&sortType=&store=1140&isSearchByPartNumber=false&fromWhere=&fromString=search&itemId=prod10684&navValue=15200113&filterByKeyWord=engine+temperature+sensor&productId=61401&appQuestionText=&searchText=engine+temperature+sensor&categoryDisplayName=Climate+Control&parentId=cat10009&questions=[]