RAM 1500 Truck 4WD V8-5.9L VIN Z (2002)
The ignition circuit sense input tells the PCM the ignition switch has energized the ignition circuit.
Battery voltage is also supplied to the PCM through the ignition switch when the ignition is in the RUN or START position. This is referred to as the
"ignition" circuit and is used to "wake up" the PCM. Voltage on the ignition input can be as low as 6 volts and the PCM will still function. Voltage is
supplied to this circuit to power the PCM's 8-volt regulator and to allow the PCM to perform fuel, ignition and emissions control functions.
POWER GROUNDS
The Powertrain Control Module (PCM) has 2 main grounds. Both of these grounds are referred to as power grounds. All of the high-current, noisy,
electrical devices are connected to these grounds as well as all of the sensor returns. The sensor return comes into the sensor return circuit, passes
through noise suppression, and is then connected to the power ground.
The power ground is used to control ground circuits for the following PCM loads:
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Generator field winding
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Fuel injectors
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Ignition coil(s)
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Certain relays/solenoids
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Certain sensors
SENSOR RETURN
The Sensor Return circuits are internal to the Powertrain Control Module (PCM).
Sensor Return provides a low-noise ground reference for all engine control system sensors. Refer to Power Grounds for more information.
