swapping immobilizers
 

So im now shopping for immobilizer repair or swapping to an immobilizer from another car. i see on ebay that you can purchase an immobilizer, dme, keys and mechanical ignition switch as a unit. my question is if i swap to a new ecu/immobilizer that has a different mileage than my cluster will that cause problems? i know if i did that to my bmw that a "tamper dot" would appear on the cluster indicating not actual mileage.

will any other problems arise from swapping dme/immobilizers?

I doo it all the time with no problems. Your cluster mileage will stay the same

Best thing to do is have it replaced by a reputable company that swaps EEPROMs.
All other options are pricey and will leave mismatched VINs and mileage (VIN is also in the cluster and climate control unit). Like Woody said, you can do it, but it's overkill and you'll have unmatched parts.

A repair shop that knows what it's doing will remove the EEPROM containing the car's VIN and stored keys from your old unit and put it into a new immobilizer, saving you a lot of trouble, work and possible issues down the road.

I fried my ECU doing some testing on a sensor, probes slipped and shorted something.

I had to replace my ECU/Immobilizer and ignition key sensor as a matched set.

As the others have said the Gauge Cluster computer must remember the mileage but the VIN and other info is from the new ECU unit.

It never occurred to me to swap the chips, but wouldn't a programmer copy of the memory and write to the new unit be the best approach?

I imagine the chips are soldered in place so if you over cook it you could lose all the data as well.