Jeep Cherokee (XJ): Automatic shutdown (asd) relay sense-pcm input. Battery voltage-pcm input. Brake switch-pcm input
DESCRIPTION The ASD 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 A 12 volt signal at this input indicates to the PCM
that the ASD has been activated. The relay is used to
connect the oxygen sensor heater element, ignition
coil and fuel injectors to 12 volt + power supply.
This input is used only to sense that the ASD relay
is energized. If the powertrain control module (PCM)
does not see 12 volts at this input when the ASD
should be activated, it will set a diagnostic trouble
code (DTC). OPERATION The battery voltage input provides power to the
Powertrain Control Module (PCM). It also informs
the PCM what voltage level is supplied to the ignition
coil and fuel injectors.
If battery voltage is low, the PCM will increase
injector pulse width (period of time that the injector
is energized). This is done to compensate for the
reduced flow through injector caused by the lowered
voltage. OPERATION When the brake light switch is activated, the Powertrain
Control Module (PCM) receives an input indicating
that the brakes are being applied. After
receiving this input, the PCM maintains idle speed to
a scheduled rpm through control of the Idle Air Control
(IAC) motor. The brake switch input is also used
to disable vent and vacuum solenoid output signals
to the speed control servoAutomatic shutdown (asd) relay
sense-pcm input
Battery voltage-pcm input
Brake switch-pcm input
Other materials:
Description and operation
Horn system
DESCRIPTION
A dual-note electric horn system is standard factory-
installed equipment on this model. The standard
equipment horn system features one low-note horn
unit and one high-note horn unit. The horn system
uses a non-switched source of battery current so that
the system will ...
