Outputs

AIR CONDITIONING (A/C) CLUTCH RELAY- PCM OUTPUT
DESCRIPTION
The A/C relay is located in the Power Distribution Center (PDC). The PDC is located in the engine compartment. Refer to label on PDC cover for relay location.

OPERATION
The Powertrain Control Module (PCM) activates the A/C compressor through the A/C clutch relay. The PCM regulates A/C compressor operation by switching the ground circuit for the A/C clutch relay on and off.

When the PCM receives a request for A/C from A/C evaporator switch, it will adjust idle air control (IAC) motor position. This is done to increase idle speed. The PCM will then activate the A/C clutch through the A/C clutch relay. The PCM adjusts idle air control (IAC) stepper motor position to compensate for increased engine load from the A/C compressor.

By switching the ground path for the relay on and off, the PCM is able to cycle the A/C compressor clutch. This is based on changes in engine operating conditions. If, during A/C operation, the PCM senses abnormally low idle speeds it will de-energize the relay. This prevents A/C clutch engagement. The relay will remain de-energized until the idle speed increases. The PCM will also de-energize the relay if coolant temperature exceeds 125° C (257° F) or low or high system pressure exists.

AUTO SHUTDOWN (ASD) RELAY-PCM OUTPUT
DESCRIPTION
The ASD relay is located in the Power Distribution Center (PDC).

OPERATION
The ASD supplies battery voltage to the fuel injectors and ignition coil(s). With certain emissions packages it also supplies voltage to the oxygen sensor heating elements. The ground circuit for the coil in the ASD relay is controlled by the Powertrain Control Module (PCM). The PCM operates the relay by switching the ground circuit on and off.

J1850-PCM INPUTS/OUTPUTS
OPERATION
The Powertrain Control Module (PCM) sends certain output signals through the J1850 bus circuits. These signals are used to control certain instrument panel located items and to determine certain identification numbers.

Refer to Instrument Panel and Gauges for additional information.

DATA LINK CONNECTOR-PCM INPUT AND OUTPUT
DESCRIPTION
The data link connector is located at the lower edge of the instrument panel near the steering column.

OPERATION
The 16-way data link connector (diagnostic scan tool connector) links the Diagnostic Readout Box (DRB) scan tool or the Mopar Diagnostic System (MDS) with the Powertrain Control Module (PCM).

FUEL PUMP RELAY-PCM OUTPUT
DESCRIPTION
The fuel pump relay is located in the Power Distribution Center (PDC).

OPERATION
The PCM energizes the electric fuel pump through the fuel pump relay. Battery voltage is applied to the fuel pump relay when the ignition key is ON. The relay is energized when a ground signal is provided by the PCM.

The fuel pump will operate for approximately three seconds unless the engine is operating or the starter motor is engaged.

GENERATOR FIELD SOURCE (+)-PCM OUTPUT
OPERATION
This output from the Powertrain Control Module (PCM) regulates charging system voltage to the generator field source (+) circuit. The voltage range is 12.9 to 15.0 volts. Models of previous years had used the ASD relay (directly) to apply the 12 volt + power supply to the generator field source (+) circuit.

GENERATOR FIELD DRIVER (-)-PCM OUTPUT
OPERATION
This output from the Powertrain Control Module (PCM) regulates charging system ground control to the generator field driver (-) circuit.

IDLE AIR CONTROL (IAC) MOTOR-PCM OUTPUT
DESCRIPTION
The IAC motor is mounted to the throttle body.

OPERATION
The motor is controlled by the Powertrain Control Module (PCM).

The throttle body has an air control passage that provides air for the engine at idle (the throttle plate is closed). The IAC motor pintle protrudes into the air control passage and regulates air flow through it. Based on various sensor inputs, the PCM adjusts engine idle speed by moving the IAC motor pintle in and out of the air control passage. The IAC motor is positioned when the ignition key is turned to the On position.

A (factory adjusted) set screw is used to mechanically limit the position of the throttle body throttle plate. Never attempt to adjust the engine idle speed using this screw. All idle speed functions are controlled by the PCM.

OXYGEN SENSOR HEATER RELAYS-PCM OUTPUT
DESCRIPTION
The 2 oxygen (O2) sensor heater relays (upstream and downstream) are located in the Powertrain Distribution Center (PDC).

OPERATION
Engines equipped with the California (NAE) Emissions Package use four O2 sensors.

Two of the four sensor heater elements (upstream sensors 1/1 and 2/1) are controlled by the upstream heater relay through output signals from the Powertrain Control Module (PCM).

The other two heater elements (downstream sensors 1/2 and 2/2) are controlled by the downstream heater relay through output signals from the PCM.

To avoid a large simultaneous current surge, power is delayed to the 2 downstream heater elements by the PCM for approximately 2 seconds.

RADIATOR COOLING FAN RELAY-PCM OUTPUT
DESCRIPTION
The pulse width modulated (PWM) radiator cooling fan relay is located behind the front bumper fascia below the right headlamp.

OPERATION
The PWM relay is used to control the speed of the electric radiator cooling fan. It allows for multiple fan speeds. This allows for improved fan noise and A/C performance, better engine cooling, and additional vehicle power.

PWM relay operation is controlled by the Powertrain Control Module (PCM). To operate the PWM relay, the PCM looks at inputs from:
- Engine coolant temperature
- Ambient temperature from the body controller
- Vehicle speed
- Transmission oil temperature
- A/C switch position (A/C request)