I have a 1991 RS. The other day I was taking off my passenger side exhaust manifold. While I was taking it off I realized there was a broken sensor that was inbetween the back 2 bolts. I want to replace this sensor, but have no idea what it is. Does anyone know what this sensor possibly could be?

 

Sounds like the coolant fan switch to me.

 

Ok, thanks, I am going to try to get a picture of it tomorrow to post. It had a plastic housing that was shattered.

 

Did it look like this?

 

Benm is right on. Everyone detroys this sensor when they remove the manifolds. I annihilated mine doing the same thing

 

I've learned a lot about this part since I've been on TGO. You can get an upgrade on this switch if you need it that will make your fan come on at cooler than stock temps and thereby enhancing your ability to cool the engine. On top of a lower than stock stat, this has greatly improved my engine's operating temp.

Here is a good reference thread (with pics!)

 

i got mine from hypertech.

 

This is a picture of the wire. It had a plastic housing, but thats shattered now. The second picture is of what that wire plugs into. What do you guys think it is?

 

where the arrow is pointing

 

Yep, it's definitely the fan switch. But, as you know, both the fan switch and the connector for it are broken.

 

OK, thank you, so i will need the new connector and the switch. Where could I get one? Which kind do you recommend? And how do I put the connector back on, solder it?

 

Is there any possible way it could be my knock sensor?

 

no, the knock sensor is farther down....i am also another that has broken that switch when installing headers.

 

Well in this pic it looks pretty far down. Isn't it right above the starter? Wouldn't it be the knock sensor thats down that far?

 

No, it's definitely the fan switch. The knock sensor is located in the engine block right above the oil pan. Here's what the knock sensor looks like:


As for a new fan switch and connector, you can get a stock replacement fan switch at any auto parts store, but it turns the fan on somewhere above 230*. Both Jet and Hypertech make cooler temp. fan switches for our cars (check out Summit Racing or Jegs for them), but they cost over $40.

But, you can get the same fan switch for $13 here, part number 609-106. And if you buy the "conversion harness", it will come with the connector you need: http://www.madvet.com/shop?frame=1.138.944

If you just want a connector, try here:
http://www.turbocity.com/product_inf...products_id=88
http://www.rosesandwrenches.com/conn...tors&UID=10037

I know in the 2 above links they are referred to as knock sensor connectors, but it will work. The connector for the knock sensor and the fan switch are the same kind.