it's a bit more on the relearn procedure. once you can communicate with the truck and the laptop using the free version, you'll need the paid version to perform the relearn procedure.
once you have the engine all back together, the first step is to have it running and up to operating temp (at least 170 deg F) then for ease of access I would recommend having the upper intake horn removed from the engine so that you can access the three nuts holding the IP to the engine.
a little bit of caution here... make sure there are no fuel leaks and the fuel system doesn't have any air. the easy way to check for air is to remove the return hose from the IP (short 5" piece from the IP to the steel return line) and replace it with a clear hose. You can get the clear hose from any local home depot or hardware store, it does not have to be fuel rated hose, we are just checking to see if the IP is passing any air bubbles.
after you've verified that there isn't any air in the line get you a solid piece of board or a clipboard, something handy that you can lay flat over the intake opening to choke out the engine just in case it attempt to "run away" this will insure you can kill the engine manually if needed.
Before you start the engine with the intake horn removed, make sure that any and all thing are out of the way from being able to get sucked into the intake. leaves, dirt, tools, grease rags ect...
now, take your wrench and loosen the bottom two nuts holding the IP leaving the top one secure so the IP won't turn on you with the engine running. connect the laptop, connect to the PCM and start the truck leaving it idling. verify the engine is again up to operating temp.
Below is a run down on the procedure which sums it up (I copied this from another forum thread), but there are some cavorts, and some helpful tips to getting it close in the first try.
if the IP is too far advanced or retarded when you begin, there will be a code that comes up and the offset reading will be out of range. I will go into some detail on how to get it into range and possibly get it dead on on the first try in the next couple of posts.
- Start GMTDScan Tech.
- Connect to your truck.
- Go into the dashboard view and verify that the engine coolant temp is at, or above, 180 °F. If not, wait before proceeding.
- Go into the DTC view and verify that no trouble codes are present.
- Go into the TDC view.
- Take note of the current DES/ACT/TDCO values. OEM is +3.5°/+3.5°/-0.5°.
- Click the TDC Time Set ON button. DES should now read 0° and ACT should read +3.5° on average.
- Click the TDC Time Set OFF button to go back to normal operating mode.
- Click the TDC Learn ON button. The TDCO value will now fluctuate for about 20-30 seconds before setting itself. You can end the sequence prematurely by clicking the TDC Learn OFF button. The current TDCO value will then be set in the PCM.
- If you are not happy with the TDCO you get you must turn the injection pump. Towards the drivers side is "+" and towards the passenger side is "-". A 2mm move equals 5° so take it very easy and do not attempt to turn the injection pump while the engine is running!
- Repeat the TDC Learn procedure until the TDCO you want is attained.