What is the difference between a Half Bridge and a Bridge output?

A Half Bridge Output is capable of either supplying system Voltage, or providing a Ground path for an externally powered device.  A Full Bridge Output combines two Half Bridges and allows for bi-directional control of devices such as motors.  A common use case for a Bridge Output in the M1 is to control the motor in a Drive By Wire throttle system.

Each Half Bridge is capable of supplying 9A or grounding 12A, a Full Bridge has the same constraints.  The Half Bridges have internal recirculation via an internal high side FET, so they can be used on loads such as VVT solenoids with needing an external recirculation diode to be installed into the wiring.  The RMS current is 4A.

The Half Bridges are capable of PWM operation, for low side (ground) switching they will run at 20KHz, high side (Supply) switching is 1KHz.

Note: Parasitic power feed is possible through these outputs, ensure that all loads wired to these outputs are supplied though switched power.

Operation

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Half Bridge Output 1 and Half Bridge Output 2 make Bridge Output 1
Half Bridge Output 3 and Half Bridge Output 4 make Bridge Output 2
Half Bridge Output 5 and Half Bridge Output 6 make Bridge Output 3
Half Bridge Output 7 and Half Bridge Output 8 make Bridge Output 4
Half Bridge Output 9 and Half Bridge Output 10 make Bridge Output 5

The Small Form Factor M1 ECU's (M122, M130, M170) have 3 Bridge Outputs available.  The Large Form Factor M1's have 5.

If one of the Half Bridge Outputs in a pair have been allocated to other functions, then that Bridge is not available to use. So as an example, if Half Bridge Output 1 is allocated to the Primary Fuel Pump, Half Bridge Output 3 to the Coolant Fans and Half Bridge Output 5 to the VVT, then there will be no Bridge outputs available to use.