Hey guys,

Had my 84 GSL SE up on the hoist here at work yesterday. Was tearing the throttle body apart and cleaning it out. Figured I'd change the oil at the same time. I noticed while I was under there, that the "Oil Thermo Switch" was busted. The end of the switch came right off the wire.

I've called Mazda, got the part manual out, FSM out.. I cant find this damn switch *anywhere* on either. Even the Mazda dealership thinks it's freaking crazy. Everyone is going out of their minds trying to figure out what this switch does, or its function. I also need the part number to order one, if its important.



Labeled "THERMO OIL SWITCH"


Guys, what is that thing?! Help me out, Thanks

-Jordan

 

If I remember right it is the switch that controls the subzero system.

 

^ What Chris said. On if the temp of the oil in the pan is below 0 degrees. Off the rest of the time.

 

What does this switch actually do if it's working properly and "sees" below 0 degrees? Does it somehow open the vacuum port on top of the engine that the rubber line runs to from the sub assist reservoir? I ask because if I take the line off my reservoir, there is never any vacuum present in the line, and it runs right into the top of the engine. I want to put seafoam in the reservoir, and be able to have it sucked into the engine only when I want it to. This should feed both rotors, right?

 

When the switch is on (below 0) it grounds the sub-zero motor to turn it on. I believe it is small pump like a ww washer. Haven't really studied it much except how to get rid of it. Pretty sure I won't be needing it in Florida.

 

So the only thing that switch does is turn of the reservoir's pump? How can the stuff it's pumping enter the engine if there is no vacuum present in the line? I'd really like to understand how this works...

 

Sub zero start assist injects coolant from a separate reservoir into the carb or intake for de-icing or engine sealing I cant remember (for easy starting in cold conditions). I see no reason why that sensor would be linked to the oil pan; that just makes no sense in my head.

So I have my doubts if that sensor is linked to that system.

 

it is, its got its own page in the wiring diagram. power comes either from the circuit opening relay, or start terminal of the IGN switch, and the sensor in the pan is the ground.

make sense or not, that's how they did it

 

the FSM doesn't say, but it looks like the thing on the intake might just be a check valve

 

It's confusing because Mazda calls it the oil thermo unit in the FSM emission control sections, but on the wiring diagram its called the sub-zero sensor.