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Discussion Starter · #1 ·
I replaced the ignition switch in my 2004 Pilot. I am using the original key, original immobilizer, and original key/lock sensor. The vehicle started, ran for about five second, and shut off. Now it cranks over but won't start. There is not a flashing green key light. The ACG S 15 amp fuse is not blown. The vehicle cranks, but won't start with the key fob, either. Where do I start to troubleshoot?

Brian
 

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I don't believe you can simply replace the ignition switch without reprogramming the PCM/ECU to recognize the new switch. I may be wrong though. Someone hopefully that has done this will pop in on this one for you.
 

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I believe that the programming applies to the ECU, the immobilizer sensor, and the RFI chip in the key. The lock cylinder is not electronic, and the switch itself is just that, an electrical switch rotated by the lock cylinder.

Recheck your install of the old immobilizer and the new switch. Make sure all the connectors are properly seated and no wires are pulled loose or damaged. Make sure that the cylinder and switch are properly mated.

I'm willing to be corrected by someone who really knows, but I think that you should be able to get it working.
 

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Discussion Starter · #5 ·
AFAIK, that is correct, after changing ignition switch,, there needs to be some programming, that's what I have read ...
Thank you. I agree. The electrical components were not replaced and I have no green key light flashing. I'll continue my search.
 

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I believe that the programming applies to the eCU, the immobilizer, and the RFI chip in the key. The lock cylinder is not electronic, and the switch itself is just that, an electrical switch rotated by the lock cylinder.

Recheck your install of the old immobilizer and the new switch. Make sure all the connectors are properly seated and no wires are pulled loose or damaged. Make sure that the cylinder and switch are properly mated.

I'm willing to be corrected by someone who really knows, but I think that you should be able to get it working.
 

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I’m with STMech on this one since the key fob and immobilizer were reused. I can’t see how replacing a mechanical part would require a ECU reprogramming. But I also haven’t performed this job so I could be wrong.
I’d definitely check the wiring integrity as mentioned above. If you didn’t disconnect battery negative before starting the job I’d check (preferably with a multimeter) the applicable fuses.
 

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Was the key itself reused? On the early Pilots, fob and key are two separate things. Fob has nothing to do with immobilizer. Key has everything to do with immobilizer. If you re-keyed your Pilot, then you do need to reprogram.
 

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Discussion Starter · #10 ·
Was the key itself reused? On the early Pilots, fob and key are two separate things. Fob has nothing to do with immobilizer. Key has everything to do with immobilizer. If you re-keyed your Pilot, then you do need to reprogram.
As it turns out, the ACG S 15 amp fuse was blown. I could not see the separation in the fuse element. I tested it with a meter and confirmed it was bad. All is well now.

Tha ks to all foe your input. It was very helpful!
 

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Did you all (some) really think Honda was going to make it that easy for car thieves ?

"Just swap the ignition cylinder and be GoodToGo" ? :ROFLMAO:

Your video man is full of shit. The lock cylinder jams because the wafers wear out. I have fully disassembled the cylinder/switch/immobilizer on my 2003. I removed the worn wafers, reassembled the whole thing, and everything now works perfectly. It is possible to replace only the switch and reuse everything else, as the OP did. Give your snark emoji a rest.
 

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Your video man is full of shit. The lock cylinder jams because the wafers wear out. I have fully disassembled the cylinder/switch/immobilizer on my 2003. I removed the worn wafers, reassembled the whole thing, and everything now works perfectly. It is possible to replace only the switch and reuse everything else, as the OP did. Give your snark emoji a rest.
Stick your snark remarks where the sun don't shine

 

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This is my speculation. The ECU expects the correct value from the immobilizer chip reader in order to start. There are three scenarios where I can see a reprogramming being required:
1) ECU replaced
2) New key(s) cut, with immobilizer chip, which the ECU does not recognize.
3) The entire ignition module is replaced. This would mean the immobilizer reader needs to “handshake” with the ECU before being operational. According to one of the videos above this reprogramming step is necessary.

The reprogramming requires a specific hardware/software tool. We know the dealer has access to this tool, and depending on which locksmith you go to they may as well. There might be other tools which can be used by the home mechanic (I won’t state my thoughts on that since I don’t want to give a car thief any ideas, although it would take so much time I would imagine they’d move to an easier target.).

If a car thief were to cut a key, for a vehicle with an engine immobilizer, the ECU will not recognize the reported immobilizer chip value and will not start. No car manufacturer with a factory engine immobilizer would make it that easy for a car thief.
 
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As it turns out, the ACG S 15 amp fuse was blown. I could not see the separation in the fuse element. I tested it with a meter and confirmed it was bad. All is well now.

Tha ks to all foe your input. It was very helpful!
Glad you got it figured out. Never trust your eyes when looking at a fuse element.😁
 
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