i recently bought a crash damaged uk 55plate rx8 to sort out and keep. it was mostly suspension damage and i have pretty much got it all sorted.

the problem is it came without keys. i got a local specialist to come out and make me a key and it all went great until he tried to plug into the EOBD port and could not get any communication. i also got my snap on machine out and found i could not connect either. checked all the fuses under the bonnet but all seems fine. so i am left with an uncoded key that turns the ignition on but nothing else. anyone got any ideas? read somewhere that the ecu bay be locked. how can i tell? any help would be great! thanks in advance.

 

Have you checked the fuses in the cabin? Not sure if this applies the 8, but my last car the a/c and horn fuse gave power to the obd2 plug and some ecu functions.

Hope this helps.

 

will check them tomorrow. car is on the 2 post ramp at the min and cant quite get the passenger door open.

thanks

 

check the 15A (blue) room fuse on the interior kick panel, it is the power supply wire for the PCM

 

checked all interior fuses and there all fine. still no communication. any ideas? dont want to take it to a main stealer's if its something simple. starting to think it may be my only option.

cheers for the advise so far though.

 

Would the immobilizer stop co
Communication to the ecu?

 

I wouldn't think so. The problem would seem more basic like a wiring issue or equipment failure.

 

hmmmm that's what worries me. got some good news today though. managed to get in touch with the previous owner and he has a key. should have it Monday. hopefully it will just fire straight up and the connection problems will be nothing to worry about. fingers crossed. failing that i need a wiring diagram for the ecu plug to see if it is all ok. if that's all fine then i am thinking 2nd hand ecu, immobilizer boxes and key. why is nothing ever simple???

 

Good to hear and problem solved, if that's the case.

 

still not got the original keys. hopefully i will get them soon. still puzzled by the connection issues. just hope it fires straight up when/if i get the key.

 

well got the keys today and its still the same with the originals. :-( got ignition but immobilizer light flashing.

someone must have an idea???

 

Has the steering column been accessed/damaged?
Perhaps the pick-up coil for the key chip is dislodged or disconnected.

There are two other fuses in the engine bay that send the ECU it's power - they are 10 amp, marked 'engine'.

If you still need a wiring diagram, drop me a pm.

 

steering column looks fine. i will have a look at it though. when i wait for the immobilizer light to stop flashing fast i get the code 1 6.

where is the immobilizer box located? thinking maybe something could have been rattled loose/damaged in the crash.

don't want to take it to the stealer's but i am starting to run out of options.

 

I AM FACED WITH THE SAME PROBLEM.
Different scenario and mine is on a 2009. but I am getting a no connection to pcm also. The dealership says the car needs a new computer and I just cant believe that as the night before, the car was running fine.
The immobilizer is not at fault---dont chase that. its light is going off because it too cannot communicate with the computer.
My harness is good, my fuses and relays are good. The pcm is getting power as my cel light is on.
But for some reason, NOTHING can connect with it, not even the dealerships equipment.
I am in the process of selling this car (cheaply) one reason is because this has been so fustrating. IF it is a dead computer then I have to know what made it die? No one has been able to tell me. One tech said lightening struck it--lol!!

 

sorry to hear your having the same problem. thought it was just me though lol. well had mine to the dealers today and they suspect the PCM. they are removing it and checking the wiring to confirm.

looks like i will be sourcing a 2nd hand pcm. anyone know for sure if it has to be a matching pcm immobilizer and key or can i just change the pcm?

 

dealer has to load your cars built data and then the security system and keys all have to coordinated. Its a PITA.
It would be wise to try and find out why the pcm died and there is no guarantee your replacement one will not do the same thing?

 

problem solved!!!!! wooo!!!!

turns out the car was totally missing a fuse. something to do with the throttle valve or something. said maybe the police removed it to immobilize the car as it was stolen and recovered. whatever it was i dont care as its sorted now. my troubles are over...for now.