Hi, everything Ok with my 05 Tribute until last week. Vehicle cranks but no starts.
Went to a series of checks and came with this;
-When ignition switch is in ON,
*The light of the security (little car) lights on for a couple of seconds then shuts off, as normal. So I believe PATS is ok.
*Fuel pump runs as normal, for 3-4 seconds, then shuts off.
*All 4 Injectors and 4 coils have +
*No + on crankshaft sensor and no + on camshaft sensor.
-When ign switch is in RUN;
*Starter motor spins ok. Battery voltage is ok. Fuel pump is working and injectors are pulsating.
*Coils has + but receive NO ground, No pulsating.
*Cam & crank sensors NO +

I clip jumped the Inertia Fuel Shutoff Switch and the Fuel Pump Driver Module, car still the same.
Then removed the Smart junction box (the fuse panel inside the center console, behind dash panel)
Checked all connectors and they look ok. Removed all fuses and relays, very carefully then removed the plastic covers and no signs of burns or damage of any kind. Replaced all back in place and, car still the same.
Reading on the internet they say that when you have no ground on the coil, most possible cause is a coil driver (in the ECU) but 4 coil missing ground all at once raises some suspicion not being the ECU.
Anyways, I removed the ECU (the module below the windshield) and opened the cover to visual inspect it and everything looks Ok,no burns anywhere, also the 4 drivers looks ok.

Finally I called in a locksmith to discard a possible immobilizer issue. It read 2 keys programed in the vehicle.
He added a new key, so now I have 3 keys programed. The car still the same.
The security light, never blinked, but I wanted to discard the PATS possibility.
I've heard a lot of issues on Expeditions coming from the smart junction box, they have a lot of micro relays
soldered to the motherboard, actually 2 or 3 motherboard sandwiched that make very difficult to test these micro relays.
Connected a scanner before and after the tests, and no DTC's stored in ECU. Nothing, nada!
During all these tests I used a battery charger/starter so the battery don't go down.

Any ideas?....I'm all ears!
Thanks!!!

 

I have seen PCM's / ECU's go bad in these before. Might be worth sending it away for testing.

 

Has it logged any codes?

Have you checked the engine ground straps, should be good if the engine cranks but worth double-checking...check the ECU ground is good.

Note the fuel pump will shut off if either fuel pressure is detected but no cranking OR no fuel pressure detected (in case there is a leak). See if the fuel pressure switch closes by looking for continuity change across it as the pump shuts off, test static and cranking, although it sounds more ignition-related if it doesn't fire <at all>.

 

I contacted 2 local Auto computer rebuilders, they say they only repair faulty coil drivers on these units.
When they go bad, they are very easy to spot, you will see them burnt. As mine (all 4) look ok physically, the issue should be somewhere else.

 

No codes, before and after all the tests I performed.
All ground straps are ok.
Not checked continuity on Fuel Pressure Switch, but it has + when ON.

 

UPDATES

Replaced ignition switch and car still the same.
To discard a possible factory alarm issue I programed a remote fob (original unit from Ford).
Never had a fob before. Now all 5 doors locks/unlocks and alarm works, but car doesn't start

I've been from one end to another of the wiring looking if it's rubbing somewhere with the chassis causing a short or some possible rodent bite in the wires (I've seen this case before but not in this car) also checked all connectors in the way and everything looks ok.

 

UPDATE:
I've been looking at local junkyards for the ECM and/or BCM and only found the BCM with matching part#s.
I removed the BCM from a light crashed vehicle, so the car was working before it was wrecked.
Replaced BCM and car is still the same. Only change was that the remote fob I programmed before was
no longer working. I programed the remote again and it works but car still with the same symptom.
Cranks but no starts.

 

Was there no change in the anti-theft light behaviour?

I'm not sure if the BCM and ECM need to be coded to each other for PATS in which case that would give you a no start in any case - although I think it is the fuel pump (according to wikipedia anyway) and maybe the starter.

 

No, no change in the anti-theft light. The keys are stored in the ECM. The remote fob stores at the BCM.
Instructed by my locksmith, on these Ford/Mazda CAN system vehicles, when there is a PATS issue, you will have NO signal to the starter. So, no crank at all. My issue is Crank but no start, coils has + but no -.
In other vehicles (and/or older systems) if there is an issue with the immobilizer, engine will crank but ECM will
cut injector pulse after 1-2 seconds, engine dies and security light blinks. Thanks for checking Simonsi!
I'm aiming to the ECM now.

 

I had a diesel Discovery once that had the 1/2sec start run/inhibit, in the 175,000 miles the immobiliser kicked in twice (but was easy to spot), locking/settle/unlocking the car resolved it both times...but on yours I'm back to suspecting the ECM ground (ie the route the COPs take to ground when pulsed by the ECM, or the Fuel pressure switch - check that as even if failing you may have 12v on one side as the Tribute tends to be switched ground in most places...

You could also try putting some gas down the inlet and see if you get any firing (it won't run but may indicate fuel or ignition). You could also try removing a front COP but leaving it wired in, fit a plug and ground the side of the plug then see if she sparks...old school but I don't have much else to suggest and you are into it for $$$ already :-(