All,
I am helping out a friend (wife and I) who has a 2001 Town and Country with a 3.8L. The engine has almost 200K and was reliable.

After owning the vehicle for 3 years she was driving out of a parking lot and vehicle motor just died.

She had the vehicle towed to a local garage who told her that they believe the issue was electrical in nature but could not pin point the problem. Mechanic friend (35 years) owns his own garage and is known through the church we both belong.

During my normal tests, I could hear the fuel pump/relay and tested for spark.

No spark was diagnosed across all front plugs which made me question the crank sensor at first but after replacing no change.

Next I decided to check fuses and voltage at the coil pack. (Should have done this first) The Haynes manual gives me the impression that the green-orange wire should have voltage but all that is available is blue-orange at the coil so I tested for 12 volts across each of the 4 wires separately. No voltage was measured.

The Haynes manual shows a connection point just prior in the electrical diagram so I traced the wires back to another connection which I located and then I started to see a possible problem. Small amount of wiring that is bare. Started to pull the outer cover back to find large sections of melted wiring. I then followed the other side of connection (close to the "side exhaust pipe") to what appears to be rewrapped wiring all the way down the one side of engine (drivers side). I did not proceed any further and was more concerned with the large melted section. It was getting late. I have separated the wires and tried to rewrap quickly to see if I could restart the engine. No dice.

I am not out my realm here with what I believe is a case of the wiring harness fell against exhaust but I do have a few questions;

1) Does anyone have a detail wiring schematic of the engine wiring.

2) Please confirm that there should be one wire with voltage (assuming 12 volts) at the coil and that the ECM/computer is just switching on/off ground to charge the coils/etc.

3) I am seeing a starter relay in the circuit in the Haynes manual is that a actual replaceable relay in the fuse panel/on the vehicle or is it the key ignition? (found this wording late last night originally I assumed it was the key ignition). The engine rotates and cam/crank are turning.

4) What will minimally be required to start the vehicle again. (After the wire repair what should I look for before initial start). (Looking for the series of items required which will engage the coils/injectors)

5) Thinking of correcting the bare wire by heat wrap by removing each wire from the connector. Or worse case cut the wire out and replace with new wire/connector and rewrap/cover or possibly new wire harness. Any other ideas?

6) What possible damage could have been done... I see and am surprised that there is no blown fuses. Could there be damage to the computer?
If so, how can I confirm - Have OBD II reader etc but not overly versed but am a Software Engineer (17 years)?

Assuming the sensors etc are probably ok....but let me know if anything could be a issue....

I know this is a big request.
Thanks,
Chris

 

1) Yes. Send me an email address to send them to in a private message. How? Right click Raptor 07. (Edit)

2) Yes. Pin 2 brown/white tracer gets constant power from the Automatic Shutdown Relay (ASD) as long as the PCM is getting good data from the cam/crank sensors. With a test light connected at all three of the other contacts, the light should blink as you crank the engine.

3) Yes, the starter relay is in the fuse box and is replaceable. If it doesn't get a ground from the PCM it won't energize and send power to the starter bendix and the starter won't crank. It's cranking. At least that circuit works.

4) Do you want an explanation of how the system works? You turn the key to start the starter rotates the engine. The cam/crank sensors sense rotation and send timing data to to the PCM. The PCM sees this then grounds the ASD relay. The relay sends voltage to the coil, fuel injectors, O2 sensors and fuel pump relay. The PCM sensing good data sends grounds to turn on individual coils and injectors as timing demands. If all is well meaning the engine has correct spark, fuel pressure and timing, the engine starts.

5)Everything you ever want to know about that wire harness and how to fix or repair it with pictures: http://forum.chryslerminivan.net/sho...wn-and-Country

6) Yes, the computer (PCM) can be damaged. For you and I all we can do is check for codes with a scanner and verify power and grounds are good.

 

Raptor's answer must be the best I've ever read on a website like this. Congrats.

Leedsman.

 

Can't seem to get this forum to allow me to send a private message.

Remove the AT and replace with the @ symbol.

cmgray74 AT gmail.com

Thanks,
Chris

 

SolomonMan - Three engine control and one starting system diagrams on their way. If you need more let me know.

Leedsman - Started off on forums ten years ago trying to find out how to "defuzz" headlights. I've been hooked ever since. Might say I'm addicted. Thanks.

 

Raptor 07,
Thanks so much for the diagrams!

Was curious was there a page(s) that defines the connection numbers/s numbers in the electrical schematic.

If it does, could I trouble you one last time for that page.

Figure it may come in handy if I have to "find" a location etc.

Thanks again,
Chris

 

You're looking for something that IDs the connections on a module correct? No I don't have that. Without it you'll have to correlate the wire color IDs for individual pins on a connection from the diagram to the connector you're looking at and see if they match up, If you see a half dozen matches then you've found the right connector.

I did find this diagram for the IPM on the net: http://ww2.justanswer.com/uploads/do..._CONN_VIEW.png

 

Raptor 07,
Thanks for the response!

I will do it that way.

Just hoping this "burn" issue is isolated....

Thanks again,
Chris