Ok I am tryin to figure out something. I have a '96 Tahoe and I am swapping in a 2000 LQ4. The 6.0 came from a Silverado 2500 that had 4.10s, my Tahoe has 3.42s. How horrible would I run leaving the PCM alone? Or can I change this with tech2? Or would I need to go to the dealership?


Please help!!!

 

You have to get a custom tune done on the pcm regardless to turn disable the passlock and other codes for various things related to emissions you may or may not use during the swap. When the tune is done they will set the correct axle ratio for you and get it tweaked perfectly so it's a nice install where everything works correctly and not a hack job.

Dealership can't do anything for you all they can do is OE GM programming. Tech 2 does not have capability to turn off codes or disable features.

 

You need a gen3 pcm and harness for this swap. Your 96 computer will not work, and even if it did, the gen3 computers are much better. Look for a 2001-2002 pcm from a 2500hd.

 

Got the harness, PCM, and everything from the flexplate forward as far as the engine is conserned. I plan to get HpTuners but right now I gotta work with what I got. I'm in college for auto and my teacher was sayin the I may be able to use the tech2 for changing the gear ratio. I haven't gotten to that point yet but I'm tryin to be prepared before I get there.

 

Read post 2 again. Info is provided to you by a GM tech.

If you do not have a tune done you will not even be able to get it to start because of the factory passlock antitheft built into the pcm.

 

The Tech 2 and TIS can change the gear ratio, tire size and correct the speedo signal in LS type PCM's



Speed Calibration Reprogramming
1. With the Tech 2®, select Service Programming.

2. Identify vehicle information as requested by the Tech 2®.

3. Select the type of module you are programming.

4. Select the type of programming to be performed.

5. Verify the displayed VIN with the vehicle VIN. If the displayed VIN does not match the actual VIN, write down the actual VIN and correct the VIN at the Techline® terminal.

6. When complete, Exit Service Programming.

7. Turn OFF the Tech 2® and disconnect the Tech 2® from the vehicle.

8. Turn OFF the ignition.

9. Connect the Tech 2® to the Techline® terminal.

10. Select Service Programming.

11. Select Tech 2® as the tool you are using.

12. Select the type of programming to be performed.

13. Verify the displayed VIN with the vehicle VIN. Correct the VIN as necessary.

14. Select the type of module you are programming.

15. Select Speed Calibration. You need to know how to get to this place

16. Select Normal.

17. After the download is complete, turn OFF the Tech 2®.

18. Disconnect the Tech 2® from the Techline® terminal.

19. Install the Tech 2® to the data link connector (DLC).

20. Turn ON the Tech 2®.

21. Turn ON the ignition, with the engine OFF.

22. Select Diagnostics.

23. Select the correct model year of the vehicle.

24. Select XXXXXXXXXXXXXXX

25. Select Powertrain.

26. Select the correct engine size.

27. Select the correct transmission for the vehicle.

Important: Be sure to select the correct transmission for the vehicle. Even if the correct axle ratio and tire revolutions per mile are entered if the transmission selected is not correct for the vehicle, inaccurate speedometer calibration will result.

28. Select Special Functions.

29. Select Engine Output Controls.

30. Select Speed Calibration Reprogramming.

31. Select Reprogram Speed Calibration.

Important: This procedure will allow the user to change the speed calibration for the vehicle. This procedure should only be done when a new ECM/PCM has been installed or when the axle ratio or tire size has been changed.

32. Select Done to continue.

33. Enter the axle ratio using the F0 through F9 keys on the Tech 2® key pad.

34. Select Done.

35. Enter the tire revolutions per mile using the F0 through F9 keys on the Tech 2® key pad.

36. Select Done.

37. At this point all entered information can be verified if anything needs to be changed. Select previous screen and the input information can be changed.

38. If the information entered is correct, select reprogram and the Tech 2® will indicate Reprogram Successful.

39. At this point if for any reason the Speed Calibration still needs to be changed select restart. The axle ratio and tire revolutions per mile can be re-entered again without having to go back to the Techline® terminal.

 

You still gotta have tis 2 web to do it the tech 2 by itself cannot do the above. All the noobies think tech 2 is a magical machine that does all lol.