Speardog

I know about the ECT switch on the Thermostat housing and I believe i have to use a jumper wire in the plug to test it or does that just test the wiring?

Also, there is some type of sensor on the engine near return coolant hose at the bumper side of the engine, what is that for?

amoebiasis

You can test the fan by simply connecting the battery straight to the fan connector.

Not sure what sensor you are referring to. Are you talking about the small sensors on the tranny side of the block? There are two coolant temp sensors there, but they dont effect your fan (I think).

Former User

If you unplug the 2-wire coolant temp switch on the thermostat housing and jump the plug with a wire, the radiator fan should run continuously with the key in ON(II). If it does, then the switch may be bad. But bleed the cooling system prior to replacing the switch as air trapped in the cooling system can also prevent the switch from activating.

There are two other coolant sensing devices under the distributor, the 1-wire sender unit for the dash temp gauge and the 2-wire ECT sensor that sends temp signals to the ECU.

Speardog

I am assuming those other 2 sensors are independent of fan control.

BTW, the fan does operate when I use a jump wire with the plug

Former User

Speardog

It was the switch, replaced it today,everything works normal. BTW, how do you bleed the system with my motor? I don't believe there is a bleeder screw anywhere.

Former User

This procedure may take 20-30 minutes:

1) Park the car on an inclined driveway with the front end higher than the rear.

2) Push the dash heater lever/**** to MAX heat.

3) Follow the directions in the diagram below

9tailsfox

hi there, I got similar problem with my civic 1992 b16a 2nd gen overheat problem. my radiator fan not running. i checked fuse work fine, relay work fine, the only thing coolant thermal sensor (ECT). I'm a chinese who not really great in english. So i'm sorry. Ok straight to the point. what do u mean by following below... I confused how to test it.
or Can you simply draw the picture? thank you

If you unplug the 2-wire coolant temp switch on the thermostat housing and jump the plug with a wire, the radiator fan should run continuously with the key in ON(II). If it does, then the switch may be bad. But bleed the cooling system prior to replacing the switch as air trapped in the cooling system can also prevent the switch from activating.

There are two other coolant sensing devices under the distributor, the 1-wire sender unit for the dash temp gauge and the 2-wire ECT sensor that sends temp signals to the ECU.

Former User

When you unplug the wire harness connector for the coolant temp switch on the thermostat housing, you will see two terminals (1 and 2) in the connector when it is viewed end on. Short circuit those two terminals in the connector with any short piece of wire (often referred to as a jumper wire) or even a paper clip.

HondaPartsHero

9tailsfox

hey, thanks man. surprising quick respond and thanks for the picture...... cool +3

9tailsfox

Hi, there I jump the connector by using a wire. The radiator fan immediate start running. So is this more than 89% my got a bad ECT Sensor. Thank you.