Sudden Stall, Now No Crank, Flashing PATS, No Odometer!

[Broosedamoose]

So I've spent an hour or so looking thru the search finds but nothing like this! I was driving my truck (07 XLT 4.0, 4WD) and the engine quits. I throw it in neutral and try to start but get nothing. So I pull over and put it in park. Turn the key and it starts right up. Drive about 2-300 yards and it quits again. I pulled over and try to start it but nothing this time. I wondered if it may be the alternator went bad with me knowing and driving on the battery killed it. However, headlights were plenty bright. I get in and turn the key and it starts right up! Now I'm scratching my head. Take off, get on the freeway and drove about 2 miles and it quits again. Now, when turn the key I get no crank, the theft light flashes rapidly and the odometer displays only dashes. Got towed home and put the scanner on it but it can't communicate with the PCM so no codes. I've tried my other keys, checked all related fuses/relays, verified voltage at the PCM (11.9 volts), and checked PCM grounds! Before I give the PCM it's last rights is there anything else you think I should check that may be the issue? I did replace the Thermostat Housing (AGAIN) last week but I hardly think that has anything to do with it.

 

[adsm08]

If you can manually start a session with your scanner do that and see if you can talk to the other modules. That would verify the data lines.

Test resistance between pins 2 and 10 at the DLC. If the narrow side is "down" they are the second pins in from the left, top and bottom. Should read 60ish ohms. 60 is good, 120 is bad, zero is bad.

You can also unplug the PCM and resistance test the lines between the DLC and the computer itself. This would only be needed if you have an incorrect reading between 2 and 10.

 

[Broosedamoose]

I just came in from doing that exact thing; checking the data lines! LOL! Too funny. I will go back out and check those pins tho! I'll let you know what I find.

 

[Broosedamoose]

So here is what I got:

I was also told to check for a voltage of 5.0 at the TPS (Grn/Vlt wire) because if it goes bad and is shorting out will cause the same symptoms. Unfortunately I couldn't be so lucky! Perfect 5.0 VDC present.

So it's gotta be the PCM! My concern now is "what caused it to go bad"! I'd hate to buy another PCM only to put it in and get fried because of an external issue!

 

[rusty ol ranger]

They can just go bad...