Hello! I'm trying to help a friend and really appreciate any knowledgeable opinion.

Friend's 2008 honda Fit was damaged as someone who had apparently no idea what they were doing tried to steal it off the street. They accessed the area of the ignition tumbler, etc around steering column and broke a bunch of stuff and left. Notably the antenna ring aspect of the immobilizer was broken. (Also the plastic housing behind the clock spring with the wiper controls etc was broken as well as the plug from the wiring harness that connected there. )

My solution was to replace the complete steering column with one from the junk yard as this was the cheapest option. There wasn't a local 2008 fit available so a junk that pulls parts and mails them sent me the complete steering column with ignition key. After re-pinning broken plug that feeds the wiper control and installation of complete new steering column the vehicle wouldn't start obviously due to immobilizer system (green key light indicator is there when I tried) so we towed it to the dealership service center to have immobilizer reprogrammed.

Honda dealership shop failed to be able to reprogram the set up saying: "Communication failure between ECM/PCM and immobilizer unit/ Key Registration failure." They didn't give any further codes just this description. Dealership shop took apart covers and checked parts/my job installing replacement steering column and concluded it all appeared visually compatible and all plugs fit etc. They diagnosed the junk yard immobilizer to needing to be replaced.

Rather than have them do this (it was an expensive quote), I now found a 2008 Honda fit at a local junk yard in person (this time I compared the VIN and first digits are a match and it appears to also be the base model), removed the steering column and the immobilizer box/antenna ring piece (this junk yard part had no key). I got access to my friends vehicle (Kinda funny to work on a car in the parking lot of a dealership a dusk), and installed just the newly acquired junk yard antenna/immobilizer to the steering column.

Honda dealership again tries to reprogram, now saying "Programming keeps failing & giving DTC code A-3" further dealership says "we need more info. What year are you getting you are getting the parts from? May be wrong year? Possibly recommend new key to start with?" This is where we have left it over the weekend.

OK, I couldn't confirm what vehicle the 1st replacement steering column came from as this was mail order. I did notice the key came with a key fob which our vehicle were trying to repair does not. Not sure if that indicates a totally incompatible security system beyond the immobilizer. That said everything fit together perfectly. I checked all the plugs and wires, all matched in color and order (when they sent me the replacement steering column, they just cut the wiring harness rather than disconnect plugs! so I had them for comparison).

Regardless my plan now is to take the ignition tumbler that fits original key off the original steering column, along with attached electrical components and attach that to the second steering column I got. (The one that i confirmed similar VIN, year, etc). This seems to remove completely the variable of the mail order steering column being incompatible.

Is this going to work? Can used immobilizer and computer be reprogrammed to communicate and match the security codes? (the dealership took on the job as if that was no issue but at times their communication has been confusing like half the time maybe they didn't understand they were parts from a junk yard). If this should work, why didn't it fix the issue when I just changed the immobilizer unit? are there other pieces to the security system beyond the key, immobilizer unit and computer that could be the issue?

(Finally, I'm very confident that I re-pinned that seemingly unrelated plug for the wipers correctly but if not is there a relay through there or elsewhere that could be causing an issue? The door locks are seized on this vehicle and I know security system has a connection there, could that be causing an issue with this reprogramming process?)

 

Any reason replacing immobilizer box/antenna that fits over the ignition with a junk yard part would not be able to be reprogrammed to work with original key and the vehicle CPU?