We’ve just replaced the engine in our 2005 G35 Coupe (has an automatic transmission) with a donor engine from a 2008 M35 sedan. The harness from the G35 plugged directly in to all the sensors that came equipped in the M35 donor engine. We did not change any of the sensor from G35 engine to M35 donor engine.

We have run in to an abnormal condition where the vehicle will not crank over. When the key is inserted in to the ignition, the vehicle chimes and the security light blinks. When the key is put in to the acc & on position, the gauge cluster lighting comes on & the security light goes out. When the key is turned to the start position, the starter does not engage, the gauge cluster lighting goes out & the security light stays off. When the key is returned to the run position, the gauge cluster lighting comes back on & the security light stays off.

All plugs have been inspected, Ground wires ohm’d, battery checked & charged.

Looking for thoughts on things we should consider testing. We’ve looked through several NATS / Immobilization posts – however our security light condition does not match the behavior from our research.

Thanks!

 

How long was the ECU unplugged from battery power, it's POSSIBLE the 1.5v backup battery is old and died and it lost the nats which isn't part of the eprom. If you have a second key try it, also try the nats reset from the ignition switch (Google it).

You can follow the troubleshooting steps from the FSM to check pins at the ecu for proper signal.

Also, my gut is saying that something isn't hooked up properly since you just fill ished the swap, I would go through EVERY harness and verify there are no bent/broken pins or damaged wiring. Check chassis/engine grounds and fusible link + all fuses. Particularly at the IPDM which houses the ecu relay.