2003 4.6 XLT 4X4
Wife was driving down the road and the engine shut off.
No warning, nothing strange, engine just stopped running.

Turn the key, no relay noise, no fuel pump noise, no starter.
Code reader won't link up.
Odometer only displays dashes.

OK experts, do you think the PCM is Dead?

Wouldn't be the first computer issue for this vehicle if it is.

 

This may not help you any. But I do know that when I tune my truck and make changes to the pcm with my programmer it does display dashes and the theft light blinks. So possibility.

 

Check the PCM fuse (and all fuses for that matter).

 

Check your Cig lighter fuse, then the PCM power relay.

 

Forgot to add
All fuses and fusable links in the box are good
Haven't checked the relays yet, I will try that in the morning.

 

I vote for the pcm relay but there's a separate diode for it too. Next to the air conditioner one, swap them and orient in the right direction.

 

It may not be related, but the same thing happened many years ago to my wife on her old fox chassis LTD- everything went dead- after a week of with a volt meter,it turned out to be a badly corroded wiring harness connector up in the fender above the headlight- cut out the connector, splice and heat shrink, all fixed!
I will never forget that one!

 

Thanks for the tips
I'll try them and let you know what I find ( or don't find)
Haven't had a chance to mess with it yet

 

Well, if it's not something simple as mentioned already...no communication or link is bad sign. You could go a step further and check signal to to coils and and injectors with a noid light or Low Volt test light. The light has to be 6 volt capable (not just 12v). But a noid is easy and quick. Just attach it to a coil or injector connector and crank the engine. The light will blink as you crank the engine. This will confirm signal from the PCM to coil/injector.

This will test PCM integrity, but remember, you have to make sure you don't have a PATS issue before hand. That has to be ruled out first. Otherwise a new PCM and the trouble you'll have to work through connecting/programming naught be for naught. No what I'm saying, -it's PCM or PATS as long as you followed up on everything mentioned in your thread to this point. 03's are PATS heavy so double check. I also don't think you can purchase per-programmed PCM for your truck off the shelf (not totally anyway with the updates). You can with other gen 10 models.

 

Relays are good
Where is this diode you mentioned?

Jbrew- noid light won't help at this point, no crank
How would I test the PATS?

I did find somebody online that claims to have PCMs programmed to your VIN with all current updates, but they say I would have to get a locksmith to re-program my keys to even know if the new PCM cured the problem.

A little back story on this vehicle. It's an Expedition not an F series (with over 200k miles) but I didn't want to join another forum and figured they are close enough to get answers here.

About 7-8 years ago the alternator stopped charging on a family vacation. Replaced it myself and 2 days later on the way home the PCM decided to lose its mind. It was quite interesting when the PCM told the Alternator to send 20 volts through the system at 3am. It's amazing how bright low beams can get.
I put the bad alternator back on it in a rest stop ( figured no charge was better than over charge). Limped into a dealer when the sun came up, got a rental and came back for it 3 days later. They had to replace the PCM.

3 years ago the PATS computer behind the fuse block went bad, luckily it happened in the driveway this time.
Came home one day, parked, 5 min later no crank, but relays and fuel pump were humming as they should be when the key was turned on and the odometer displayed as it should. The PATS computer was humming like crazy when this happened. It's not doing that this time.

I'm trying to fix it myself this time as I don't want to spend more than this thing is worth.

Throw me some more ideas before I drop the dough on a new PCM.