Found an identical salvage yard rig to mine (2002 HO w/six speed trans) and bought the ECM & PCM to be used as backups in case mine go out. Any issues or procedures when swapping out the ECM from one rig to another. The donor rig was totaled but the engine bay looked fine (mostly front end steering linkage damage). The donor had 60K less miles than mine and both computers were OEM so should be in good shape. I'm assuming I can just change the ECM with no need for a re-flash or anything?
TNX...Mike

 

Been doing a few Google searches and it looks like the ECM might need to be re-flashed with my VIN. Anyone tried this and who did the re-flash for you?

 

I' not sure about the 02, but the ECM and PCM need to match(VIN, Flash level), else the theft protection can kick in. I don't know if there are more parts that you'd need to get from the donor to get it working properly.
Also there may be problems with the mileage displayed. (Maybe also legal consequences if mileage displayed is less than mileage run in case you sell it)

 

Well, just got the PCM and ECM installed and was a little surprised but it worked perfectly. I did spend time to source out a rig that was absolutely identical to mine which might have been the trick. I also grounded out the donor ECM before starting the truck. This clears the ECM capacitors and memory so when you start up it takes a little time to learn your rig config. You also need to do an APPS reset after this. It needs to know where your peddle (idle to full) settings are. Anyway, the rig started right up and odometer was right on. The trip meter and clock are the only items that changed and that's normal. Took it for a test run for about 30 minutes and checked for codes with a ScanGauge. All looked good. I thought for sure the ECM would need a re-flash but lucked out on this swap. I had already run down a local Auto Computer shop who would re-flash the ECM if needed. Just wanted these two items for spares as my wife and I travel a lot. We're good to go!

 

Anyone know for sure if odometer readings are stored in the PCM or the ECM? I'm thinking PCM at this point but that's a guess.
Anyone?

 

I think that the visible info is stored in the gauge cluster, but there should be an hour counter in the ECM and mileage stored in the PCM.
Both can be read out via OBD2 and at least over here vehicles that are sold used are frequently checked for mismatches between odo and PCM, with a sanity check about hours and fuel counter (if applicable) in the ECM.

 

"visible info is stored in the gauge cluster, but there should be an hour counter in the ECM and mileage stored in the PCM"
That sort of makes sense with what I'm seeing. Since I never had the ECM re-flashed to get the correct VIN burned in, I'm guessing that if the the rig was scan with the proper reader my use of a donor would show up. As I'm just using these two donor computers as an emergency backup I might not care. If I actually had to use them full time I suppose I could have it re-programed and everything would be up to date and legit. Is that how you see it?

 

At least over here it's like that:
If you want to sell it and there's a module with higher mileage than you state it's fraud. ( If you state odo reads 100 k miles, but PCM reads 200 k miles- no fraud, you'll get the price for 200k. )
If you don't sell it it's a non issue. (over here)

Please take into account that this is an abbreviated view of the ramifications in a different jurisdiction.