Replaced alternator now crank no start. 06 4.7 limited

[fordhorse]

Events:
-Started fine/normal multiple times had battery light.
-Confirmed not charging.
-Had battery checked while waiting on alternator.
-Replaced alternator with reman parts Authority Denso unit.
-Crank no start.
-Found no wiring damage or blown fuses.
-Replaced alternator with Toyota Denso unit.
-Crank no start.
-Checked every fuse both visually and electrically "Multimeter".
-What relays I could find potentially relating to charging/starting circuit seem to be ok "swapped with other relays."
-Odd observances- Engine continues to crank for approximately 10secs even if key is released from start position to run position, the key must be turned back to accessory position to immediately stop cranking. Also aftermarket remote start/keyless entry no longer communicates with vehicle.
Original alternator case was split/cracked, never seen this before in person but have heard about it.
Was a mechanic for years, so not my first alternator rodeo, battery was disconnected for entire job.
I am digging deeper but was hoping someone had more exposure to this insanity.

 

[rdruss]

Just a guess, but I'd say your aftermarket remote start not communicating with ECM has something to do with it.

 

[fordhorse]

Agreed, just not wanting to remove and eventually reinstall somebody else's electrical work to diagnose my suspicion. And I struggle with why would it have communicated normally until battery light came on. Or did it happen when battery and alternator where reconnected. I just don't see any smoking guns.

 

[Cezar]

Engine continues to crank for approximately 10secs even if key is released from start position to run position, the key must be turned back to accessory position to immediately stop cranking.

Normal.

If there are no codes it almost has to be an immobilizer issue. I feel like I recall that there is a light on the gauge cluster that shows immobilizer communication status.

 

[alia176]

Engine continues to crank for approximately 10secs even if key is released from start position to run position,


This is interesting. Don't all 4th gens have the "auto start" feature, where you barely hit the START mode with the key and the ECU cranks the engine until it starts?

Did you download the EWD for your MY and see where the ECU isn't allowing the engine to start?

 

[AuSeeker]

Engine continues to crank for approximately 10secs even if key is released from start position to run position,


This is interesting. Don't all 4th gens have the "auto start" feature, where you barely hit the START mode with the key and the ECU cranks the engine until it starts?

Did you download the EWD for your MY and see where the ECU isn't allowing the engine to start?

This is correct all 4th Gens have auto crank until the engine starts, so that isn't a issue in this case, that part seems to be functioning correctly, he apparently isn't getting spark to the plugs I would think, why is the question, I agree there's a lost of communication with the ECU, as mentioned check to see if the lights for the immobilizer are acting correctly.

 

[MikeinNH67]

Can you hear the fuel pump run? Does it do anything with a wiff of starter fluid in the intake? As mentioned, the 10 second thing is normal. I got used to just blipping the key and letting mine start itself. It's been a while since I installed my remote starter but I think they use the OBD plug to communicate. You may want to find that and try disconnecting it for now.

 

[Babs187]

Fun issue to diagnose, (not for you im sure) sorry your experiencing this. first as others have said, the lack of comms between your remote start and car are throwing up some warning signs. instead of fully disconnecting can you remove the fuse for the remote start? or just remove one of the wires that is related to power from the battery? how fast is it spinning over? are your lights on while you try spinning? if everything is spinning as fast as it should, and with the remote start disconnected it still isnt firing, move then to spark. if you have spark at a plug (pull one and see, just dont touch the electrode or ceramic) then its time to consider fuel issues. if you have fuel at the injectors move over to check grounding for ECU/ECM. finally if that isnt the culprit, roll it into a body of water and call your insurance (obviously kidding)