My newest issue with my 98 civic is at idle the temp gaude starts climbing to the red, cooling fan dosent come on until it is in the red. Then it stays on until the temp is 208 according to my scan tool. So I get the chiltons out to check the switch, it says at that temp there should be continuity between the 2 terminals and to check this with an ohmeter, so I do and nothing comes up, tried the diffrent settings all the way up to 200k and still nothing. Did I do this test right???? Is my switch bad..

 

The switch sounds dead. Insert a jumper wire into the 2P connector for the switch. Just like when you jump the service connector. When the key is turned to ON(II), the fan should run continuously. If so, replace the switch.

 

pretty much the same way I jumped the SCS connector for the timing right..

 

Yes. Leave the jumper wire installed and run the engine to see whether running the fan continuously prevents the overheating.

 

O.K. did the jumper and the fan kicked on right away. Thanks for your help again. I appreciate it. One last question, if the switch was telling telling the gauge it was hot, how come the fans diddnt come on.

 

Your engine has at least three different temp sensors. The switch on the thermostat housing only tells the radiator fan when to turn on. It does not provide the temp signal for the gauge. The 1-wire temp sending unit located under the distributor has the latter function. A second 2-wire temp sensor located under the distributor functions to send temp signals to the ECU.

Given that the radiator fan does not turn on until the engine is overheated, the switch is bad.

Test whether running the fan continuously prevents the overheating. If not, there's another problem.

 

I will try that tomorrow. Thank you

 

Well no luck today on fixing it. Had a few problems at napa. The first switsh for 50$ diddnt have the O ring so I took it back and the guy told me theres a cheaper one for 17$. O.K sounds good right ? Nope the connector dosent snap on, or even fit on all the way... Got what I paid for.. Will let you know tomorrow.

 

Got the right switch this time but now coolont is weeping out of the threads where the switch screws into the housing. The O ring is there and not damaged. Can I use a sealant on the threads ? I have some ultra black high temp silicone and some form a gasket sealant. Will either of these work ?

 

Yes, a good high-temp silicone sealant is what you need to use on the threads.