Alarm killed the engine cant start dealer says its the pcm but the key light is on? tested the pcm came back fine still wont start checked all the sensors and replaced a few and nothing? thinking its the immobiliser the light goes off when its unplugged but still nothing?

Could be connected, but could also be two different problems.
It could be something in the key switch, or a wiring problem. Or it could be a wiring problem with the temp gauge and something else causing the engine not to start.
Do you have spark and fuel pressure at the injectors ? And does the gas gauge work ?

The PCM controls the ground to the injectors. Does the check engine light come on for a bulb check when the key is turned on? Check ECM fuses in underhood fuse/relay center. There is usually 2 10 amp fuses protecting the PCM circuitry.

This is not like an aftermarket alarm. It is built into the main computer and uses both the horn and the lights to sound a warning. The keyswitch has a reader and the ignition key must match the frequency recorded in the brain of the vehicle. It also kills the power to the starter and some even kill the ignition.

A shorted Battery will trigger the alarm, so have it fully tested. The reader and the wiring to the brain could also have a break in them, triggering the system. Sometimes worn ignition switches will lose contact with the key inside the switch.

The alarm is engineered to render the car immobile if tampered with. But a Dealer can Electronically recode a new Chip key to match

alarm /immobilisor light on ?? try the spare key

Try chaning the main relay. It is $60 at the dealer, cheaper on e-bay. There is also a way to repair the sodlering connection on it if you want to try and save some money. Check youtube for a video on how to rapir main relay on Honda's. Any questions, e-mail me at [email protected]

this is a warrenty issue. have the dealer look at it.

the PCM may need to be reprogrammed by a dealer - I would also suggest seeing the dealer for any programming updates for your current PCM for this or similiar problems. I know many people think dealers are rip offs, but how mauch have you wasted at this point ??

i had this problem with mine just opening the door with the key seems to disengage the alarm so that the engine will start again

check your key remote if it is not programmed the alarm will go into the kill switch mode and will not allow you to start your engine Having the same trouble with one of my keys I haven't found a way to reprogram it without calling dealer and paying a chunk.

Try replacing spark plugs and battery, check the distributor cap.