Chrysler Repair: 1999 Town&Country Engine Fuse #17 blow, crankshaft sensor, oxygen sensors

Question
QUESTION: Hi Roland.

(excuse for my English, but this is not my native language)
I have the following issue: I own a 1999 Town&Country V3.8L LXi minivan, which works fine until 3 weeks ago. About then, my engine shut down in the middle of the road, while I was driving. After inspecting the car, my mechanic told me that some crankshaft sensor (or sensors, I'm not sure) has been broken and he replace them. I drove the car for around 100 miles and I got the same issue: the engine shut down while I was driving. I've tried to start the car, but no result. The starter works, but engine refuse to start. I've checked the fuse box and the the engine fuse was blow-out. I replace the fuse, try to start the engine, same result. The engine blow-out again. I use all the 10A fuses available in the fuse-box, same result. So I tow the car to the mechanic and he find out that it's a short-cut in the wiring. Two (+) wire (one yellow with red stripe and one red with blue stripe are getting power. He thinks (because he does not have an original wire diagram) that those two wire are for the two relays: battery relay and starter relay. The problem is that he doesn't know where these two relays are located. Could you help me?

Thanks.


ANSWER: Hi Paul-Aramis,
I don't know what he meant by a 'battery' relay; the starter relay is in the 6th socket counting from the front, adjacent to fuses 19 and 20. I assume the the 'engine' fuse that is blowing is 20 amp in position #17, counting from the front of the box, correct? If that is so, that fuse powers many devices via the automatic shutdown relay (rear-most relay), any of which could be shorted: the 2 oxygen sensors, field coil of the alternator, powertrain controller, ignition coil pack, and the 6 fuel injectors. Maybe the wrong size fuse (10A) is the cause, or a short in any one of those devices or the dark green/orange wire that carries the current from the ASD relay to each. If we are not speaking of fuse 17 then let me know the # of the fuse in question. I don't see either of the wires that he described as being involved with the #17 fuse. I wonder what the other relay is he wants to identify that he called "battery".
Roland
PS Your English is perfect.

---------- FOLLOW-UP ----------

QUESTION: You're right, my mistake is a 20A fuse (I was reading an previous answer  about a 10A fuse). I have no idea what # it is, but I will check tomorrow morning the fuse box and I will came back with the answer.

Thanks.
Paul

ANSWER: You are welcome, I await your report back

---------- FOLLOW-UP ----------

QUESTION: Hi Roland.

I've checked the fuse box this morning. It is the fuse #17 indeed. I'm attaching a picture with the plug for this fuse 8http://image75.webshots.com/175/2/38/19/2760238190104321694aGxBvc_fs.jpg), so you can see the two wires which are in short. So, the question is where is the other end for those two wires?

Answer
Hi Paul-Aramis,
Thanks for the photo. I identified the plug in the picture as being #6 associated with the power distribution center. The two wires that you listed are indeed 12v-carrying lines (the red/dark blue provides power to the relay that powers the automatice transmission, the yellow/red provides power to the starter relay actuation coil) but neither of them are related to fuse 17 which is the circuit in question that is blowing. I would suggest that you go to each of the items I listed as being supplied with a dark green/orange wire, disconnect the closest connector to the item and then noting whether there is a change from dead short to a reading which is at least one ohm (which is high enough to not blow the fuse). When you find the device which when removed causes such an increase, then that is what is shorted. It may well be that one of the oxygen sensors has a shorted wire (these are very fragile), or one of the dark green/orange wires that run from the fuse to the device has a short in its insulation.
The output of fuse 17 goes to and thru the automatic shut down relay (when the points on the relay are closed which of course only occurs when your are cranking or running the engine) and so pin 87 of that ASD relay's socket would be exactly the place to do these short-to-ground readings, and that is the middle pin of the 4 pins in the ASD socket.
Let me know what you learn or if you and the mechanic have further questions.
Roland