#3670, "RE: Removing stock computer and engine harness" In response to In response to 4
You probably know this by now, perhaps you drove around and the car eventually died , but the ECU controls the alternator. The tachometer signal is also routed in and out of the ECU same with the speedo. Must be running external radiator fan support as well. You disable the +5v reference to all the sensors as well. Disconnecting the harness disables these functions.