Ok, the fan switch on an OBDO motor is the two male plugs on the back of the block, right? If I want to upgrade this to a plug what plug do I need to get and where is it located on the motor? I was told it is the EGT switch on the thermostat housing. While searching through the archives and came across a post that said

<U>The fan switch is NOT the same thing as the ECT sensor.
Fan switch = SPST switch that closes a circuit to turn on the fans

ECT sensor = thermistor; changes resistance with temperature so the ECU knows the coolant temperature</U>

so where is the plug? And if I upgrade it to the plug does it have to be OBDO, OBD1, or OBD2 specific? And what if I upgrade the car to OBD1 in the future will this cause a problem? Thank you all of your help and support.

 

I think I might I found one answer tell me if this is right.

The fan switch is the plug that goes into the thermostat hosing, the EGT switch goes under the Vtec silinoid, and the ECT gauge goes next the the EGT switch.

If this is right, what fan plug do I need to buy to put in the thermostat hosing? OPD1 or OBD2? Or does it even matter?

 

Sensors & fan switches can change from year to year. So...
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Perfectionist &raquo;</TD></TR><TR><TD CLASS="quote">Year? Model? Please move a little to the left. I can't see your car.</TD></TR></TABLE>

On my Hondas, the fan switches are in the T-stat housing. I think before '92 or so, there was a fan timer module & a second fan switch somewhere else.

The fan switches can turn on at different temperatures, so be careful what you get to replace yours.

This part is true:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ELAMINT5 &raquo;</TD></TR><TR><TD CLASS="quote"><U>The fan switch is NOT the same thing as the ECT sensor.
Fan switch = SPST switch that closes a circuit to turn on the fans

ECT sensor = thermistor; changes resistance with temperature so the ECU knows the coolant temperature</U></TD></TR></TABLE>

This isn't true:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ELAMINT5 &raquo;</TD></TR><TR><TD CLASS="quote">... the EGT switch goes under the Vtec silinoid, and the ECT gauge goes next the the EGT switch.</TD></TR></TABLE>"EGT" is what? Exhaust-gas temperature? You probably don't have that... The VTEC oil-pressure switch usually has a green 2-wire plug. The VTEC solenoid usually has a grey 1-wire plug.

The engine-coolant temperature (ECT) SENSOR has a 2-wire plug that's usually located near the upper radiator hose. That measures temperature for the ECU.

The sender for the dashboard temperature gauge has a 1-wire plug & it's also usually located near the upper radiator hose.

I'm not sure, but I'd guess the fan switch for OBD-1 or OBD-2 is the same. If you have an older car with a fan-timer that wants 2 different switches, then learn how it works before you mess with it...

 

I have a 90 CRX with a B16A, sorry about that. So the Fan switch on the OBDO motor is the to male ends on the back of the block, right? Then what is the switch/plug on the thermostat housing then? Because isn't that switch/plug on the thermostat housing the fan switch on OBD1-OBD2 motors?

When my friend helped me install my motor last time he hooked up this little black box that has a little metal prong that I had in the radiator so when it got hot it turned the fan on. Well, I want to get ride of that black box, so I figured I would get a new fan switch ie.. relocate it to the thermostat housing. I am just trying to make complete sense of all this, before I cut the harness and spend money on a plug and switch that I may not need. Thank you for helping. This should be easy but for some reason it is a big pain in the a$$

 

I'm a little hazy on this, so try to get a wiring drawing...

Some years (not necessarily all OBD-0) there were 2 fan switches, set at different temperatures, and a timer module, along with the fan relays. What happens is that the fan switch in the T-stat housing controls the fan while the engine's running. After turning off the engine, the 2nd fan switch controls the fan, but the timer shuts it down after xx?? minutes even if the switches are still hot.

 

I see. So what happen if just bypass the switch on the back of the block and put on a new fan switch by the thermostat housing? Do you think I could mess something up?

I just bought a FULL-RACE traction bar, PWR'S new CRX radiator and have to get a new slim line fan so I figure lets get rid of that damn black box and replace the fan switchs while I am at it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ELAMINT5 &raquo;</TD></TR><TR><TD CLASS="quote">I see. So what happen if just bypass the switch on the back of the block and put on a new fan switch by the thermostat housing? Do you think I could mess something up?</TD></TR></TABLE>Yes. There's probably a way to make that work, but without a wiring drawing I wouldn't just do that.