Help with 2003 Silverado PCM swap

[balchz06]

Looking for some help with a pcm swap ? have an 03 silverado with a bad pcm (P59). Have been tuning on this truck for some time with a valid license. Got a used replacement pcm (also a P59) and can't get the truck to start, starter won?t engage at all.

-I've licensed the new pcm
-OS was different on the new pcm
-Took a prior tune from this truck and did a write entire
-OS, vehicle type and VIN showed up on the new pcm

Like I said no starter activity. I've toggled VATs on/off, tried the security relearn, the fuel pump pressurizes with key on, engine responds to special functions in the scanner. Is there something else that I need to do?

Thanks - Jeff

[Jon S.]

The 2003 P59 (1Mb) PCM and OS are unique.

The read / write protocol seems to be different than the later P59 PCMs and the 2004+ model year OS.

I stay away from these on LS conversion projects - as they seem prone to brick - even when flashed with a Tech 2 / MDI.

If you need a 2003 PCM (which it seems like you do), I would recommend getting one from a wrecking yard - from a similar 2003 vehicle.

[balchz06]

Thanks for the reply Jon. If I can find a 2003 PCM, I'll still have to license and flash it before I can use it - won't I be caught up possibly in the same situation I am now? I'll be selling the truck once I get this issue straightened out so would like to not invest any more than necessary.

[Jon S.]

The bricking issue is only when fully reprogrammed (i.e. a write entire flash) - especially with a different OS.

If you get a replacement PCM from a similar vehicle, read out the existing calibration, and then make changes to this calibration, as are necessary for your vehicle.

Updating the parameters in the replacement PCM to your requirements, would require only a calibration flash - which rarely causes an issue.

These extra precautions only apply to the 2003 P59 (1MB) PCMs.

[balchz06]

Great information, thank you Jon!