My SC 3800 conversion keeps my coolant fan running all the time. This is a new problem, and I am trying to narrow it down. I want to start with ohming out the temp sender, but need to know the values. Before I can even do that, I need to make sure I have the right sender. Can someone give me the wire colors for the sender, and the values that it should read with a cold engine?

BTW, my engine is from a 98 Grand Prix

[This message has been edited by topcat (edited 11-22-2003).]

My fan runs all the time as well.(when key is on) Keeps things cool!

Why would you want it any different?

It is too cool. I would rather have it cycle somewhat like normal. Especially on those really cool mornings. Besides that my temp gage is not working. I suspect both problems are related.

Darth explained in an earlier post that this type of problem could be the result of a quad 4 driver error in the ECM from the fan relays not being wired correctly. I am not sure if that is a real bad thing or not. I just want the fan to work right

[This message has been edited by topcat (edited 11-22-2003).]

topcat, the stock 3800 temp sender has 3 wires, green, black, and yellow. the black and the yellow are hooked to the PCM and the green is hooked to the temp gauge.

To check the coolant temp sensor you must have an ohm meter and unplug the coolant temp sensor. Remember the position of yellow and black wires. Across those two terminals, you should get the following resistance readings at temperature:

212 F -- 177 ohms
194 F -- 241 ohms
176 F -- 332 ohms
158 F -- 467 ohms
140 F -- 667 ohms
122 F -- 973 ohms
104 F -- 1.4K ohms
86 F -- 2.2K ohms
68 F -- 3.5K ohms
50 F -- 5.7K ohms
32 F -- 9.4K ohms
14 F -- 16.2K ohms
-4 F -- 28.7K ohms
-22 F -- 52.7K ohms
-40 F -- 100.7K ohms

Keep in mind these readings can vary by about 10%. Topcat, if your fan runs as soon as you start your car then you probably have a QDM fault. HOWEVER, something else just came to mind, I do remember that some PCM's will automatically turn on the coolant fan if they don't see the A/C pressure switch hooked up, or don't see the correct pressure from the A/C pressure sensor. This could also be your problem. In any event, check for trouble codes. If you don't have any, check your wiring diagrams to see what kind of A/C pressure unit is used with your system and make sure you hook one up, even if you don't put it on the A/C system. This should take care of your fan problems.

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Thanks Darth. This is just the info I was looking for. I will check out the A/C switch while I am at it.