How to Troubleshoot a 2007 Tundra 5.7 4x4 That Cranks but Won't Start?

It sounds like you're dealing with a tricky situation. Since your Tundra cranks but won’t start and there's no communication with the engine parameters, there are a few things to consider. First, check the ECM relay; a failing relay can prevent the ECM from functioning properly. If the crankshaft position sensor is faulty, it could stop the spark, but you should also hear the fuel pump prime when you turn the ignition to the "ON" position. If the fuel pump isn’t priming, the fuel pump relay might be the culprit, and it could indicate that the fuel pump itself needs replacement. Make sure to inspect all fuses and relays, especially the higher amperage ones. If everything checks out, look at the secondary air injection system. Sometimes, if it's not properly connected, it can cause issues. You might also want to try starting the truck with the air pump unplugged, as this can help isolate the problem. If you've already checked the wiring and connections for the sensors and everything looks good, consider the body grounds. A poor ground connection can lead to all sorts of electrical issues, so ensure they are clean and secure. Since the VSC light is still flashing, it could indicate a restriction preventing the truck from starting. Check the wheel sensors for any broken wires or dirt that might be affecting their performance. If all these components are functioning correctly, it’s possible that the ECM itself is faulty. If you can, try to borrow an ECM from another vehicle to see if that resolves the issue. Given that you've already done a thorough inspection, replacing the ECM might be the next logical step if all else fails.