Not all 2002 Tundras came with the same alarm system. Some used one remote and others used another remote. I believe it depended on whether the alarm was installed at the factory or was installed at the distribution point or dealer. You need to look at your alarm ECU and find the FCC ID number. This will tell you which remote you need. The FCC ID numbers need to match.
Are you talking about the engine ECU or the alarm ECU. The alarm ECU is what you want. Mine is located behind the instrument cluster and is taped to the steering column. Is this the ECU that you are looking at?