how do i know if the pcm is bad for sure on a 2002 ford expedition 4.6L

sounds like a classic case of a corroded 1/0 battery to chassis ground being corroded from over 300 amps going through that spot again and again...in effect "welding" the lug in that spot...only trouble is there is not enough area to pull 300 amps thru that spot anymore...get a coarse wirebrush...disconnect the 1/0 lug that goes to the frame and wirebrush that spot to be able to pull 300 amps----also make sure the battery is newer than five years old~ may be good but will not see the full potential unless it is new...or newish...check the push off labels on the top of the battery indicating the date of the first charge to be sure~

the pcm is NEVER bad....the ground connection to the PCM could be bad~

Judge Roy is correct, but if that does not do it, You can try to re set the Anti Theft system. Might work, especially if you accidentally put the wrong key in, it 'arms' the anti theft until re set Inside the head of the key is a transponder chip that is programmed to a certain code so that the PCM/ECU in the car recognizes the key. When you are sure you have the correct key, try to start the car with it. If the Explorer still refuses to start, move on to this: Wait 15 minutes, until you see the flashing rate on the red light on your dashboard decrease to normal speed and then try both keys again. If this still fails to start the car, raise the hood and disconnect the battery for 15 minutes, then reconnect it and try again.

howdy David~ :)

...well tarNfeather and run 'em out on a rail~ there really should be a "mark hurtful" button~

...or ground to the unit~

i have an 04 explorer that wont turn over or crank. worked great sunday night and on monday morning, it turned over 3 times then nothing. theft light flashes rapidly. battery was bad. replaced it. starter is good. starter relay is good. not turning over. can anyone help me? i was told to try the starter switch?? my truck threw the B1601 code.ford dealership couldnt figure it out. ALSO, my door ajar light is on. ive sprayed all door locks, opened and closed a million times, etc. so because of that, my lock and unlock switch on driver side does not work and neither does the keypad. someone please help me.

I have a 2002 ford Explorer and the no crank symptoms only occur when it drops below 15 degrees in the winter time. I have lights and gauges but will not crank. Was told PCM is bad.

My car doese kinda the same one day its good rhe other its bad like it dont wanna go in gear an down shift on its ain a 2006 ford explore

I have a Ford Explorer XLT 4.6L 3V V8. ODM shows a P0645 code. Hay I can solve this Issues?

How

Hey I have a 2000 Ford Expedition that just died the other morning been running fine until that point. They anti theft light came on and it would just turn over not start. Then once I got it back to the house unhooked the battery and performed reset on theft system.....now it starts but runs like crap, no communication from obd port and no instrument cluster (mileage, rpm's etc.....)

My obd gave me the wrong cord. No communication. What is the problem..?

Junk it

My 2001 ford sport trac having the same problem with the pcm losing signal from output speed shaft sensor. Ford place thinks it id the pcm because in runs and shifts good before it loses signal from transmisson. Rebuilt transmisson has 6k on it.

Does the pcm have anything to do with the a/c clutch

this is not a pcm problem all 2000-2005 ford expedition have fuse box relay to fuel pump issues an a no start no crank issue that shut it down if you go to passenger side door an remove the foot kick plate an down in bottom you'll see relays under the top fuse box these are solider to the circuit board the very middle of the box wedge something between the two center relays just enough to put pressure on it then see if it will start only way to fix this issue is to buy a new upgraded fuse box there was a recall on these I went through 3 dealer fuse boxes an fought for a refund till it was solved..

I just recently bought a 2002 Ford Expedition from an "honest" guy...seems to be a tremendous amount of these guys around here...and parked it one night to only go out in the morning to find that it wouldn't start. It cranks over but just will not fire. I tried disconnecting the negative battery cable trick to see if it would reset the pcm...still nothing. Swapped fuel pump relay and checked fuse...all good. Any other ideas?...if you really are honest?