I am having a major problem with my car. There is a black ground wire connected to the coilhttp://shbox.com/1/ICM_coil_studs.jpg
For some reason if I have any of the o2 sensors connected that wire becomes a hot wire when the ignition is on; what would cause this to happen? I know it is supposed to be ground but it is hot when I turn the key on.

 

only when the o2s are connected? did you wire your o2s in yourself?

 

Possibly a short in the O2 heater circuits, or you have the heater wires crossed if you have O2 extensions.

 

No I did not wire the o2s myself; they are in the stock location. Now for the O2 heater circuits; how would I determine that? It is on every o2; if I unplug all of the o2s and just plug each one in separately they will all cause the ground wire to go hot. It is weird I am having a hell of a time fixing this problem. The wire is defiantly going hot out of the o2. I cut the black wire and the part of wire on the loom side was not hot; but the other end on the o2 side is hot. This is happening with the key on; when the key is off the wire is not hot, but as soon as I switch the ignition on the black wire is hot.

 

I am using a break in additive in my oil; could that have caused the O2 sensors to go bad and short to the ground wire?

 

No. You have a wiring problem or a shorted heater. The heater circuit is not affected by the exhaust.

The heater circuits are on switched power. When the key is in "run" the heater circuits are powered.

Thing is, if you are shorting the 12V side of the heater wire to the ground, you should be blowing the fuse for the heater circuits, which is common to many other devices. I only have Shoebox's 95 wiring diagram, so I don't know what the 96/97 4 sensor wiring setup looks like.

Since the black wire only gets hot when the O2 sensors are plugged in, there would have to be a short in the sensor's heater circuit, but its unlikely all 4 of them would be shorted.

 

I know I was thinking why would all 4 have a short; how about If I pull a sensor off of my other vehicle and plug it it? If it fixes the problem then somehow all the sensors have a short. It is blowing the ignition fuse.

 

I swapped out one of the o2 sensors with a known good sensor and I am having the same short. I don't know what to do now. I can start the car with all of the sensors unhooked but it runs like crap.

 

It is getting power from the brn wire on pin D.

 

maybe you need to pull the loom apart and make sure there is not bare or cut wires causing this. if not i think you just need to trace the wire or find a diagram of where the wires go and start testing them.

 

The ground wire is getting power as soon as it exits the O2 sensor; it is not getting power or shorting in the loom. I clipped the black ground wire just before it enters the o2 sensor, then I took my test light and tested both ends of the black wire for power. The end on the o2 side was hot and the end on the loom side was not. So for some reason it is getting power inside of the o2 sensor.

 

If your testing it with a test light, it's going to light up if everything is working as should. Think of wiring two or more loads in series.


If you put a load (bulb) in series after another load (heating element) it's going to light up. I think you're going down a dead end here. Your short is somewhere else.

 

Could I test for a shot on a hot wire by unhooking all of the connectors then hook the test light up to the + side of the battery and probe the wires that are supposed to be hot with the test light. If the light lights up then that wire is grounding to ground some where; am I correct here?

 

The best way to find a short is to get a power distribution wiring diagram and see everything that is powered from the fuse that is blowing. Then start systematically disconnecting components from the circuit and or wiggle the wires to see if you can induce the failure. How often is it blowing the ignition fuse? Is it instant, as soon as you turn the key on? Or does it only happen under certain conditions?

 

The ignition fuse is blowing right away and the wires even heated up to the point where I could smell a melting wire smell. I did get it to start once, but it was running so bad that I had to shut it off.