While your car's transmission is regulated and managed by the TCM (transmission control module), it might exhibit issues if the ECM (engine control module) is problematic, even though they're technically separate ecosystems. For example, a bad ECM might incorrectly set the ignition timing or dump the wrong amount of fuel into the engine. In so doing, the engine's poor operation will inevitably carry over to odd problems with the transmission. You might, for instance, notice how your transmission is struggling to change gears or isn't shifting gears at all. If it's not fixed quickly, a bad ECM, in this scenario, would put added strain on the transmission. Over time, this alone would accelerate the wear and tear of the transmission, causing it to fail prematurely.