06 mazda 3 engine swap and no start

[Indian tommy]

I swapped out blown 2.3 with used after receiving 2 bunk engines, dropped cradle and tranny re installed a with provided harness on engine this car clicks at starter relay immobilizer light flashes rapid when key on and there is no signal to starter relay gray wire just main power. I have swapped harness with original add new ground from engine to shock tower on p/s, ground is solid at block by starter bolt and ground from battery to fender is there. I've tried to cycle 2 keys supplied for immobilizer and jumped gray/red brown/red at neutral safety to by pass. It seems the car is being told it's thinkin it's getting stolen and won't give me start signal or crank over. I've been at this for a few days and is frustrating. Do I need to change the cluster or am I missing a ground cause at one time even with new battery installed the lights with key on are rapid flashing like I have a ground issue my codes are U2510 and U2516. Any thoughts thanks guys and gals

[silverstarmazda]

what about the ECU? did you swap that too?

[Indian tommy]

No I didn't that's the 2 connector attached by battery

[Indian tommy]

What is a pjb in 5 he wiring diagram to do with cluster and immobilizer?

[Indian tommy]

No I didn't it's by the battery 2 large connectors

[Noisy Crow]

No I didn't it's by the battery 2 large connectors

Didn't what? We know how the ECU connects to the wiring harness -- the question was did you use the original ECU or the one that came with replacement engine? If you ussed the one that came with the replacement engine you'll need to get the cluster re-programmed to recognize it.

[Indian tommy]

No I kept the same ecu in vehicle

[Indian tommy]

Any other thoughts on ground issues or immobilizer faults and it seems I'm not getting a signal out off state relay to neutral safety even if I jump the neutral safety like maybe a break before the neutral safety maybe? I noticed it changes colors half ways thru the harness to neutral safety also

[McGuyver_3]

If your immobilizer light is flashing really fast with the key in the run/start position, then you most likely have an immobilizer issue. Go over all your important electrical connectors again. Ecu(sometimes it can "look" fastened but isn't locked in properly) fuse panel under the hood(connector in the centre) , check the PJB harness connectors, the main fuse at the battery terminal(I belive it's an 80 amp or so). If it's a stick try to bump start it and see what happens. Could be a bad starter motor. You may have pinched a wire somewhere to. Without physically seeing the car there are a lot of different variations of what could be wrong. Describing them sometimes can also be tricky

[GutsyMatt]

I had the identical problem. Took to Mazda. It turned out to be a ground that was pinched somewhere near the transmission mount. Confirm all your grounds are clean and not pinched.