i have a 89 accord lx its running hot and i think its the coolant temp sensor how can you test this.

 

The Helm manual shows how to test the thermostat, ECT sensor, & gauge sender. It basically amounts to putting it in a pot of hot water with a thermometer.

As you heat up the water, you watch the thermostat open. Or for the other sensors you hook up an ohm-meter & check the sensor resistance at different temperatures.

 

I doubt the temp sensor would fail like that. More likely the thermostat is sticking closed. Given the age of the car, a new one is only $10 -$15.

 

With my other cars that I've own, not accords, if you unplug the connector from the sensor, the fans should immideately turn on. Are your fans coming on at all?

If they are coming on, then your problem lies elsewhere.

 

With the Honda's that I've owned (other makes too), the sensor for the fuel injection is separate from the fan switch & separate from the gauge sender. Those 3 systems don't 'share' information.

It does sound like a simple stuck thermostat. What's it actually doing wrong? Overheating? Or does the gauge read high & you don't know whether to believe it?

 

My temp sensor failed a while back. The car felt like I was driving around with the e-brake on all the time. Acceleration was horrible. I raced an automatic 4dr SE just to see how f'ed up my car really was, and he destroyed me hah! Checked it out and the engine was reading a constant -40 for the temp.
Oh yeah, it broke during a clutch install.

 

thanks for all the help guys it turned out to be a bad thermostat from autozone ill never shop there again they suck.