Help me identify this!
 

Soo.... I put in a new battery couple of days ago. Today my battery light comes on. Have it checked and it is the Voltage Regulator gone bad. Seems like an easy job to replace.
I am looking at engine & alternator and I discover a black sensor or something that is bolted to the engine block below the alternator - But it looks like the blue & green wires from it have been cut or nibbled away. (I recently had signs of Mr Ratty making a home on top of engine block!)
Anybody know what this thing is or does?

Thanks & sorry for the crappy photos.http://986forum.com/forums/uploads02...1476574051.jpg
http://986forum.com/forums/uploads02...1476574072.jpg

Knock sensor.

See this link: http://986forum.com/forums/general-discussions/54756-knock-sensor-help.html

The knock sensor detects knock or (more correctly) pre-detonation in the cylinders by sensing the harsh vibrations. The ECU will then retard the ignition timing to prevent engine damage. Retarding the timing usually results in a loss of power so the engine can feel weak. The ECU will set the check engine light (CEL) if the sensor or wiring fails.

Thanks for the quick replies and info.
It looks like the wires have been cut really close to the sensor. I am thinking that maybe the knock sensor on the other cylinders is hooked up and this one is deliberately left disconnected. Maybe the motor only needs one.
I have no engine check lights & car runs great.
When I pull the alternator out next week I will look closer.

The battery light went off this morning - runs fine.
Will keep an eye on it.

Update! Rats must DIE!!!
 

So it turns out I have a bad alternator - easy.
Just it pulled it out and I can now see what Mr Rat Bastard has been up too.:mad: Apart from covering the engine block in poop & peepee he has also eaten through the wires to the knock sensor! See pic. I think I will unbolt the sensor (is it OK to do that?) trim the wires and solder it back together.
I never noticed any effect on performance - maybe I will gain some when done.:)

Off to order a new recon. Bosch alternator.http://986forum.com/forums/uploads02/rat1476755019.jpg

sure your Alt is bad? Sure its not the voltage regulator? The VR is a $50 part and bolts to the back.

I had it tested and came back as alternator bad.
I have changed a Voltage regulator before on a BMW - then the alternator went out 2 months later - so now I just do the whole thing.

Car is now back together. I had to solder new wires to the pins in the knock sensor plug.
put in new (recon) Bosch alternator. All working great.
I have heard of at least 3 instances of rats eating this sensor wire (911's & Boxsters) - I guess it is in a very convenient place for them.
I vacuumed out all the crap off the motor - Looking at the pine tree debris mixed with the chewed wire bits I think this could have been like this for years.
I am told I should have more power now....Yay! :dance:

If you have rats around you might wanna check this.