Tire Pressure Monitor Module Modes - Dodge ZB 2005 Service Manual

wheel pressure. The coil field must be applied for
six seconds in order to read the current tire air
pressure.
Lo Tire LCD Message and Warning Alert
The ''Lo Tire'' LCD message is located in the
Instrument Cluster. The message is used to inform
the driver that one or more of the tires have low air
pressure. The TPM module indirectly through the
BCM controls the ''Lo Tire'' message. The BCM
controls the ''Lo Tire'' LCD message by communi-
cating with the Instrument Cluster via the PCI
Bus. The Instrument Cluster controls the ''Lo Tire''
LCD message as well as providing a warning alert
signal to the BCM. When the ignition is first turned
on, the TPM module grounds the Low Tire Pressure
Signal circuit for 2 seconds. The ''Lo Tire'' LCD
message will be on for 2 seconds signifying that the
system is operational. If the BCM did not sense that
the TPM module has provided a ground path after
initial ignition on, and/or the TPM module has set a
DTC and is keeping the Low Tire Pressure Signal
circuit grounded, the BCM will set a DTC ten
seconds after the transition to run. The BCM will
turn the ''Lo Tire'' LCD message on, signifying a
problem with the TPM system.
TPM Diagnostic
After the Run/Start cycle and after initialization
of the TPM, the TPM module registers a TPM
Diagnostic when 1 or more tire transmitters are not
transmitting. These transmitters start to transmit
data after the wheel has reached 33 km/h (20
MPH.) Because the TPM module does not know
vehicle speed, the BCM must ignore this fault until
70 seconds after the vehicle speed is greater then 33
km/h (20MPH.) This timer keeps counting even if
the vehicle speed drops below 33 km/h (20 MPH.)
After the timer has elapsed, the BCM will monitor
the TPM module output for a fault. If the TPM
module output returns to low for greater then 3
seconds, then the BCM will set the fault and after
ten seconds, send a PCI Bus message (one or more
sensors not operating properly) to the cluster. When
the cluster receives this message, it will send a
single warning alert request to the BCM and dis-
play the ''Lo Tire'' LCD message. If this fault has not
set and the vehicle speed is below 33 km/h (20
MPH) for more than 15 minutes, then the 70 Second
timer will be reset. If the fault has set since the last
ignition on cycle, cycling the ignition switch will not
clear the fault.
Tire Pressure Low and Critical Tire Pressure
When the TPM module senses that pressure is
below one of two calibrated thresholds, Tire Pres-
sure Low or Critical Tire Pressure, the TPM module
will indirectly operate the ''Lo Tire'' LCD message
GENERAL INFORMATION
through the BCM and the warning alert through
the Instrument Cluster to the BCM.
If the tire pressure is low (20 to 14 psi), the Low
Tire Pressure Signal circuit will be pulsed to ground
by the TPM module for two seconds on and then two
seconds off. The BCM will send the ''Lo Tire'' LCD
message and the Instrument Cluster will send a
single warning alert request to the BCM. The BCM
will also set a Tire Pressure Low DTC.
If the tire pressure is critical (14 to 0 psi), the Low
Tire Pressure Signal circuit will be pulsed to ground
by the TPM module for one second on then one
second off. The BCM will then enable the ''Lo Tire''
LCD message and the Instrument Cluster will send
the PCI Bus message to the BCM to sound the
warning alert at the rate of one second off and one
second on. The BCM will also set a Critical Tire
Pressure DTC.
The module will continue to pulse to ground the
Low Tire Pressure Signal circuit until the ignition
is turned off, or the tire pressure transmitter(s)
transmits a pressure above the calibrated thresh-
old.
NOTE: A low tire pressure condition does not
set a DTC in the TPM module. The DRBIII
can be used to view the last 32 transmissions
in the module's memory and to confirm
which tire was reporting the low-pressure
condition.
If more than one condition is set at the same time,
the TPM module will prioritize when the ''Lo Tire''
LCD message will be enabled. The priority rank-
ings are listed below:
Critical Tire Pressure: ''Lo Tire'' LCD message
flashes at one second on and one second off.
Tire Pressure Low: ''Lo Tire'' LCD message
flashes at two seconds on and two seconds off.
TPM Module Initialized and TPM Diagnostic: ''Lo
Tire'' LCD message on.
Less than four ID's learned ''Lo Tire'' LCD mes-
sage on.
Transmitter Failure: ''Lo Tire'' LCD message on.
Normal tire pressure: ''Lo Tire'' LCD message not
on.
No faults: ''Lo Tire'' LCD message not on.
3.12.2 TIRE PRESSURE MONITOR
MODULE MODES
System Initialization
When the ignition is turned to the ''run'' position,
the TPM module performs a complete self-check of
all electrical components in the module.
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