2001 DODGE TOWN AND COUNTRY ESP

²Check thePCV valveand replace if necessary.
Not required if previously changed.*
²Replace thespark plugson 2.4 liter engines.
²Inspect the generator belt on 2.4 liter engines
and replace if necessary.
²Inspect the serpentine drive belt (3.3 liter and
3.8 liter engines) and replace if necessary. This main-
tenance is not required if belt was previously
replaced.
²Change the All Wheel Drive (AWD) power trans-
fer unit fluid. (See the note at the end of Schedule ±
B.)
²Inspect the tie rod ends and boot seals.
²Inspect the brake linings.
93,000 Miles (149 000 km)
²Change the engine oil.
²Replace the engine oil filter.
96,000 Miles (154 000 km)
²Change the engine oil.
²Replace the engine oil filter.
²Drain and replace the automatic transmission
fluid and filter.
²Adjust bands on 3±speed transmission. (See the
note at the end of Schedule ± B.)
99,000 Miles (158 000 km)
²Change the engine oil.
²Replace the engine oil filter.
²Inspect the brake linings.
100,000 Miles (160 000 km)
²Flush and replace engine coolant at 60 months
or 100,000 miles (160 000 km).
102,000 Miles (163 000 km)
²Change the engine oil.
²Replace the engine oil filter.
105,000 Miles (168 000 km)
²Change the engine oil.
²Replace the engine oil filter.
²Inspect theengine air cleaner element (fil-
ter)and replace as necessary.*
²Inspect the generator belt on 2.4 liter engines
and replace if necessary.
²Inspect the serpentine drive belt on 3.3 liter and
3.8 liter engines and replace if necessary. This main-
tenance is not required if the belt was previously
replaced.
²Change the All Wheel Drive (AWD) power trans-
fer unit fluid. (See the note at the end of Schedule ±
B.)
²Change the All Wheel Drive (AWD) overrunning
clutch and rear carrier fluid. (See the note at the end
of Schedule ± B.)
108,000 Miles (173 000 km)
²Change the engine oil.
²Replace the engine oil filter.
²Inspect the brake linings.
111,000 Miles (178 000 km)
²Change the engine oil.
²Replace the engine oil filter.
114,000 Miles (182 000 km)
²Change the engine oil.
²Replace the engine oil filter.
117,000 Miles (187 000 km)
²Change the engine oil.
²Replace the engine oil filter.
²Inspect the brake linings.
120,000 Miles (192 000 km)
²Change the engine oil.
²Replace the engine oil filter.
²Replace theengine air cleaner element (fil-
ter).
²Inspect thePCV valveand replace as neces-
sary.*
²Replace thespark plugson 2.4 liter engines.
²Inspect the generator belt and power steering
pump belt tension, replace the belt if necessary on
2.4 liter engines.
²Inspect the serpentine drive belt on 3.3 liter and
3.8 liter engines. Not required if replaced at 75,000,
90,000 or 105,000 miles.
²Replace theengine timing belton 2.4 liter
engines.
²Change the All Wheel Drive (AWD) power trans-
fer unit fluid. (See the note at the end of Schedule ±
B.)
²Inspect the tie rod ends and boot seals.
* This maintenance is recommended by Daimler-
Chrysler Corporation to the owner but is not
required to maintain the emissions warranty.
NOTE: Operating the vehicle more than 50% in
heavy traffic during hot weather, above 90ÉF (32ÉC),
using vehicle for police, taxi, limousine type opera-
tion or trailer towing require the more frequent tran-
saxle service noted in Schedule ± B. Perform these
services if vehicle usually operate under these con-
ditions.
NOTE: The AWD power transfer unit fluid and the
AWD overrunning clutch/rear carrier fluid must be
changed at the more frequent intervals shown in
schedule B if the vehicle is operated under any of
the conditions noted by an asterisk at the begin-
ning of the schedule.
RSLUBRICATION & MAINTENANCE0-15
MAINTENANCE SCHEDULES (Continued)
ProCarManuals.com

observed if the automatic adjuster is working prop-
erly. If one or more adjusters do not function prop-
erly, the respective drum must be removed for
adjuster servicing.
BRAKE LINES
DESCRIPTION - BRAKE TUBES AND HOSES
The brake tubes are steel with a corrosion-resis-
tant nylon coating applied to the external surfaces.
The flex hoses are made of reinforced rubber with fit-
tings at each end.
The primary and secondary brake tubes leading
from the master cylinder to the ABS ICU Hydraulic
Control Unit (HCU) or the non-ABS junction block
have a special flexible section. This flexible section is
required due to cradle movement while the vehicle is
in motion (The ICU and non-ABS junction block are
mounted to the cradle).If replacement of these
lines is necessary, only the original factory
brake line containing the flexible section must
be used.
OPERATION - BRAKE TUBES AND HOSES
The purpose of the chassis brake tubes and flex
hoses is to transfer the pressurized brake fluid devel-
oped by the master cylinder to the wheel brakes of
the vehicle. The flex hoses are made of rubber to
allow for the movement of the vehicle's suspension.
INSPECTION - BRAKE TUBES AND HOSES
Flexible rubber hose is used at both front brakes
and at the rear axle. Inspection of brake hoses
should be performed whenever the brake system is
serviced and every 7,500 miles or 12 months, which-
ever comes first (every engine oil change). Inspect
hydraulic brake hoses for surface cracking, scuffing,
or worn spots. If the fabric casing of the rubber hose
becomes exposed due to cracks or abrasions in the
rubber hose cover, the hose should be replaced imme-
diately. Eventual deterioration of the hose can take
place with possible burst failure. Faulty installation
can cause twisting, resulting in wheel, tire, or chassis
interference.
The brake tubing should be inspected periodically
for evidence of physical damage or contact with mov-
ing or hot components.
The flexible brake tube sections used on this vehi-
cle in the primary and secondary tubes from the
master cylinder to the ABS hydraulic control unit
connections must also be inspected. This flexible tub-
ing must be inspected for kinks, fraying and contact
with other components or with the body of the vehi-
cle.
BRAKE PADS/SHOES - FRONT
REMOVAL - FRONT DISC BRAKE SHOES
(DISC/DISC BRAKES)
(1) Raise the vehicle. (Refer to LUBRICATION &
MAINTENANCE/HOISTING - STANDARD PROCE-
DURE).
(2) Remove both front wheel and tire assemblies.
(3) Begin on one side of the vehicle.
(4) Remove the anti-rattle clip from the outboard
side of the caliper and adapter.
(5) Remove the two caliper guide pin bolts.
(6) Remove caliper from caliper adapter and brake
rotor.
CAUTION: Supporting weight of caliper by the flex-
ible brake fluid hose can damage the hose.
(7) Using wire or cord, hang the caliper from the
front strut assembly (Fig. 12). Support the caliper
firmly to prevent weight of caliper from being sup-
ported by the brake fluid hose.
(8) Remove the outboard brake shoe from the cali-
per adapter.
(9) Pull the inboard brake shoe away from the cal-
iper piston until the retaining clip on shoe is free
from the cavity in the caliper piston (Fig. 13).
(10) Repeat the above procedure on other side of
the vehicle.
Fig. 12 Stored Front Disc Brake Caliper
1 - STEERING KNUCKLE
2 - BRAKE FLEX HOSE
3 - CALIPER ASSEMBLY
4 - WIRE HANGER
5 - STRUT ASSEMBLY
RSBRAKES - BASE5-13
HYDRAULIC/MECHANICAL (Continued)
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ENGINE
DIAGNOSIS AND TESTING - ENGINE COOLING
SYSTEM
Establish what driving condition caused the cooling
system complaint. The problem may be caused by an
abnormal load on the system such as the following:
prolonged idle, very high ambient temperature, slight
tail wind at idle, slow traffic speed, traffic jam, high
speed, steep grade.
DRIVING TECHNIQUES
To avoid overheating the cooling system:
(1) Idle with A/C off when temperature gauge is at
end of normal range.
(2) Do not increase engine speed for more air flow
and coolant flow because the electric motor fan sys-
tems are not responsive to engine RPM. The added
cooling from higher coolant flow rate is more than
offset by increased heat rejection (engine heat added
to coolant).
TRAILER TOWING
Consult the owner's manual under Trailer Towing
and do not exceed specified limits.
VISUAL INSPECTION
If the cooling system problem is not caused by a
driving condition, perform a visual inspection to
determine if there was a recent service or accident
repair, including the following:
²Loose/damaged water pump drive belt
²Incorrect cooling system refilling (trapped air or
low level)
²Brakes possibly dragging
²Damaged hoses
²Loose/damaged hose clamps
²Damaged/incorrect engine thermostat
²Damaged cooling fan motor, fan blade and fan
shroud
²Damaged head gasket
²Damaged water pump
²Damaged radiator
²Damaged coolant recovery system
²Damaged heater core
²Open/shorted electrical circuits
If the visual inspection reveals none of the above
as cause for a cooling system complaint, refer to the
following diagnostic charts.
COOLING SYSTEM DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
PRESSURE CAP IS BLOWING
OFF STEAM AND/OR COOLANT.
TEMPERATURE GAUGE READING
MAY BE ABOVE NORMAL BUT
NOT HIGH. COOLANT LEVEL MAY
BE HIGH IN COOLANT RESERVE/
OVERFLOW TANK.1. Pressure relief valve in radiator
cap is defective, or was not
properly seated.1. Check condition of radiator cap
and cap seal. (Refer to 7 -
COOLING/ENGINE/RADIATOR
PRESSURE CAP - DIAGNOSIS
AND TESTING) Replace cap as
necessary.
2. Incorrect cap was installed. 2. Replace cap as necessary.
3. Incorrect coolant mixture. 3. Check concentration level of the
coolant. (Refer to 7 - COOLING/
ENGINE/COOLANT - DIAGNOSIS
AND TESTING) Adjust the ethylene
glycol-to-water ratio as required.
COOLANT LOSS TO THE
GROUND WITHOUT PRESSURE
CAP BLOWOFF. GAUGE IS
READING HIGH OR HOT.1. Coolant leaks in radiator, cooling
system hoses, water pump or
engine.1. Pressure test and repair as
necessary. (Refer to 7 - COOLING -
DIAGNOSIS AND TESTING)
7 - 14 ENGINERS
ProCarManuals.com

(1) Turn the ignition switch on (transmission in
park/neutral).
(2) Use the DRB III and select THEFT ALARM,
SKIM then MISCELLANEOUS.
(3) Select PCM REPLACED (GAS ENGINE).
(4) Enter secured access mode by entering the
vehicle four-digit PIN.
(5) Select ENTER to update PCM VIN.
NOTE: If three attempts are made to enter secure
access mode using an incorrect PIN, secured
access mode will be locked out for one hour. To
exit this lockout mode, turn the ignition to the RUN
position for one hour then enter the correct PIN.
(Ensure all accessories are turned off. Also monitor
the battery state and connect a battery charger if
necessary).
(6) Press ENTER to transfer the secret key (the
SKIM will send the secret key to the PCM).
(7) Press Page Back to get to the Select System
menu and select ENGINE, MISCELLANEOUS, and
SRI MEMORY CHECK.
(8) The DRB III will ask, Is odometer reading
between XX and XX? Select the YES or NO button on
the DRB III. If NO is selected, the DRB III will read,
Enter odometer Reading. Enter
the odometer reading from the Instrument Panel and
press ENTER.
PROGRAMMING THE SKIM
(1) Turn the ignition switch on (transmission in
park/neutral).
(2) Use the DRB III and select THEFT ALARM,
SKIM then MISCELLANEOUS.
(3) Select PCM REPLACED (GAS ENGINE).
(4) Program the vehicle four-digit PIN into SKIM.
(5) Select COUNTRY CODE and enter the correct
country.
NOTE: Be sure to enter the correct country code. If
the incorrect country code is programmed into
SKIM, the SKIM must be replaced.
(6) Select YES to update VIN (the SKIM will learn
the VIN from the PCM).
(7) Press ENTER to transfer the secret key (the
PCM will send the secret key to the SKIM).
(8) Program ignition keys to SKIM.
NOTE: If the PCM and the SKIM are replaced at the
same time, all vehicle keys will need to be replaced
and programmed to the new SKIM.
PROGRAMMING IGNITION KEYS TO THE SKIM
(1) Turn the ignition switch on (transmission in
park/neutral).
(2) Use the DRB III and select THEFT ALARM,
SKIM then MISCELLANEOUS.
(3) Select PROGRAM IGNITION KEY'S.
(4) Enter secured access mode by entering the
vehicle four-digit PIN.
NOTE: A maximum of eight keys can be learned to
each SKIM. Once a key is learned to a SKIM it (the
key) cannot be transferred to another vehicle.
If ignition key programming is unsuccessful, the
DRB III will display one of the following messages:
Programming Not Attempted - The DRB III
attempts to read the programmed key status and
there are no keys programmed into SKIM memory.
Programming Key Failed (Possible Used Key From
Wrong Vehicle) - SKIM is unable to program key due
to one of the following:
²faulty ignition key transponder
²ignition key is programmed to another vehicle.
8 Keys Already Learned, Programming Not Done -
SKIM transponder ID memory is full.
(5) Obtain ignition keys to be programmed from
customer (8 keys maximum).
(6) Using the DRB III, erase all ignition keys by
selecting MISCELLANEOUS and ERASE ALL CUR-
RENT IGN. KEYS.
(7) Program all ignition keys.
Learned Key In Ignition - Ignition key transponder
ID is currently programmed in SKIM memory.
BODY CONTROL MODULE
DESCRIPTION
The Body Control Module (BCM) is concealed
below the driver side end of the instrument panel in
the passenger compartment, where it is secured to
the dash panel.
The BCM utilizes integrated circuitry and informa-
tion carried on the Programmable Communications
Interface (PCI) data bus network along with many
hard wired inputs to monitor many sensor and
switch inputs throughout the vehicle. In response to
those inputs, the internal circuitry and programming
of the BCM allow it to control and integrate many
electronic functions and features of the vehicle
through both hard wired outputs and the transmis-
sion of electronic message outputs to other electronic
modules in the vehicle over the PCI data bus.
8E - 2 ELECTRONIC CONTROL MODULESRS
ELECTRONIC CONTROL MODULES (Continued)
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(M) Check Engine Lamp (MIL) will illuminate during engine operation if this Diagnostic Trouble Code was recorded.
(G) Generator Lamp Illuminated
GENERIC SCAN
TOOL CODEDRB SCAN TOOL DISPLAY DESCRIPTION OF DIAGNOSTIC TROUBLE CODE
P0071 Ambient Temp Sensor Preformance Ambient change less than 3É C in 200 Miles
P0106 (M) Barometric Pressure Out of Range MAP sensor input voltage out of an acceptable range
detected during reading of barometric pressure at key-on.
P0107 (M) Map Sensor Voltage Too Low MAP sensor input below minimum acceptable voltage.
P0108 (M) Map Sensor Voltage Too High MAP sensor input above maximum acceptable voltage.
P0111 (M) Intake Air Temp Sensor Preformance Intake Air change less than 3É C in 200 Miles
P0112 (M) Intake Air Temp Sensor Voltage Low Intake air (charge) temperature sensor input below the
minimum acceptable voltage.
P0113 (M) Intake Air Temp Sensor Voltage High Intake air (charge) temperature sensor input above the
maximum acceptable voltage.
P0116 Engine Coolant Temp Performance A rationatilty error has been detected in the coolant temp
sensor.
P0117 (M) ECT Sensor Voltage Too Low Engine coolant temperature sensor input below the minimum
acceptable voltage.
P0118 (M) ECT Sensor Voltage Too High Engine coolant temperature sensor input above the
maximum acceptable voltage.
P0121 (M) TPS Voltage Does Not Agree With
MAPTPS signal does not correlate to MAP sensor signal.
P0122 (M) Throttle Position Sensor Voltage
LowThrottle position sensor input below the acceptable voltage
range.
P0123 (M) Throttle Position Sensor Voltage
HighThrottle position sensor input above the maximum
acceptable voltage.
P0125 (M) Engine Coolant Temp Not Reached Time to enter Closed Loop Operation (Fuel Control) is
excessive.
P0130 1/1 O2 Sensor Heater Relay Circuit An open or shorted condition detected in the ASD or CNG
shutoff relay control ckt.
P0131 (M) 1/1 O2 Sensor Shorted To Ground Oxygen sensor input voltage maintained below normal
operating range.
P0132 (M) 1/1 O2 Sensor Shorted To Voltage Oxygen sensor input voltage maintained above normal
operating range.
P0133 (M) 1/1 O2 Sensor Slow Response Oxygen sensor response slower than minimum required
switching frequency.
P0134 (M) 1/1 O2 Sensor Stays at Center Neither rich or lean condition is detected from the oxygen
sensor input.
P0135 (M) 1/1 O2 Sensor Heater Failure Oxygen sensor heater element malfunction.
P0136 1/2 O2 Sensor Heater Relay Circuit An open or shorted condition detected in the ASD or CNG
shutoff relay control ckt.
P0137 (M) 1/2 O2 Sensor Shorted To Ground Oxygen sensor input voltage maintained below normal
operating range.
P0138 (M) 1/2 O2 Sensor Shorted To Voltage Oxygen sensor input voltage maintained above normal
operating range.
P0139 (M) 1/2 O2 Sensor Slow Response Oxygen sensor response not as expected.
8E - 10 ELECTRONIC CONTROL MODULESRS
POWERTRAIN CONTROL MODULE (Continued)
ProCarManuals.com

(M) Check Engine Lamp (MIL) will illuminate during engine operation if this Diagnostic Trouble Code was recorded.
(G) Generator Lamp Illuminated
GENERIC SCAN
TOOL CODEDRB SCAN TOOL DISPLAY DESCRIPTION OF DIAGNOSTIC TROUBLE CODE
P0140 (M) 1/2 O2 Sensor Stays at Center Neither rich or lean condition is detected from the oxygen
sensor.
P0141 (M) 1/2 O2 Sensor Heater Failure Oxygen sensor heater element malfunction.
P0143 1/3 O2 Sensor Shorted To Ground Oxygen sensor input voltage maintained below normal
operating range.
P0144 1/3 O2 Sensor Shorted To Voltage Oxygen sensor input voltage maintained above normal
operating range.
P0145 1/3 O2 Sensor Slow Response Oxygen sensor response slower than minimum required
switching frequency.
P0146 1/3 O2 Sensor Stays at Center Neither rich or lean condition is detected from the oxygen
sensor.
P0147 1/3 O2 Sensor Heater Failure Oxygen sensor heater element malfunction.
P0151 (M) 2/1 O2 Sensor Shorted To Ground Oxygen sensor input voltage maintained below normal
operating range.
P0152 (M) 2/1 O2 Sensor Shorted To Voltage Oxygen sensor input voltage sustained above normal
operating range.
P0153 (M) 2/1 O2 Sensor Slow Response Oxygen sensor response slower than minimum required
switching frequency.
P0154 (M) 2/1 O2 Sensor Stays at Center Neither rich or lean condition is detected from the oxygen
sensor.
P0155 (M) 2/1 O2 Sensor Heater Failure Oxygen sensor heater element malfunction.
P0157 (M) 2/2 O2 Sensor Shorted To Ground Oxygen sensor input voltage maintained below normal
operating range.
P0158 (M) 2/2 O2 Sensor Shorted To Voltage Oxygen sensor input voltage maintained above normal
operating range.
P0159 2/2 O2 Sensor Slow Response Oxygen sensor response slower than minimum required
switching frequency.
P0160 (M) 2/2 O2 Sensor Stays at Center Neither rich or lean condition is detected from the oxygen
sensor.
P0161 (M) 2/2 O2 Sensor Heater Failure Oxygen sensor heater element malfunction.
P0165 Starter Relay Control Circuit An open or shorted condition detected in the starter relay
control circuit.
P0171 (M) 1/1 Fuel System Lean A lean air/fuel mixture has been indicated by an abnormally
rich correction factor.
P0172 (M) 1/1 Fuel System Rich A rich air/fuel mixture has been indicated by an abnormally
lean correction factor.
P0174 (M) 2/1 Fuel System Lean A lean air/fuel mixture has been indicated by an abnormally
rich correction factor.
P0175 (M) 2/1 Fuel System Rich A rich air/fuel mixture has been indicated by an abnormally
lean correction factor.
P0178 Water in Fuel Sensor Voltage Too
LowFlex fuel sensor input below minimum acceptable voltage.
P0179 Flex Fuel Sensor Volts Too High Flex fuel sensor input above maximum acceptable voltage.
RSELECTRONIC CONTROL MODULES8E-11
POWERTRAIN CONTROL MODULE (Continued)
ProCarManuals.com

(M) Check Engine Lamp (MIL) will illuminate during engine operation if this Diagnostic Trouble Code was recorded.
(G) Generator Lamp Illuminated
GENERIC SCAN
TOOL CODEDRB SCAN TOOL DISPLAY DESCRIPTION OF DIAGNOSTIC TROUBLE CODE
P0182 CNG Temp Sensor Voltage Too Low Compressed natural gas temperature sensor voltage below
acceptable voltage.
P0183 CNG Temp Sensor Voltage Too High Compressed natural gas temperature sensor voltage above
acceptable voltage.
P0201 (M) Injector #1 Control Circuit An open or shorted condition detected in control circuit for
injector #1 or the INJ 1 injector bank.
P0202 (M) Injector #2 Control Circuit An open or shorted condition detected in control circuit for
injector #2 or the INJ 2 injector bank.
P0203 (M) Injector #3 Control Circuit An open or shorted condition detected in control circuit for
injector #3 or the INJ 3 injector bank.
P0204 (M) Injector #4 Control Circuit Injector #4 or INJ 4 injector bank output driver stage does
not respond properly to the control signal.
P0205 (M) Injector #5 Control Circuit Injector #5 output driver stage does not respond properly to
the control signal.
P0206 (M) Injector #6 Control Circuit Injector #6 output driver stage does not respond properly to
the control signal.
P0207 Injector #7 Control Circuit Injector #7 output driver stage does not respond properly to
the control signal.
P0208 Injector #8 Control Circuit Injector #8 output driver stage does not respond properly to
the control signal.
P0209 Injector #9 Control Circuit Injector #9 output driver stage does not respond properly to
the control signal.
P0210 Injector #10 Control Circuit Injector #10 output driver stage does not respond properly to
the control signal.
P0300 (M) Multiple Cylinder Mis-fire Misfire detected in multiple cylinders.
P0301 (M) CYLINDER #1 MISFIRE Misfire detected in cylinder #1.
P0302 (M) CYLINDER #2 MISFIRE Misfire detected in cylinder #2.
P0303 (M) CYLINDER #3 MISFIRE Misfire detected in cylinder #3.
P0304 (M) CYLINDER #4 MISFIRE Misfire detected in cylinder #4.
P0305 (M) CYLINDER #5 MISFIRE Misfire detected in cylinder #5.
P0306 (M) CYLINDER #6 MISFIRE Misfire detected in cylinder #6.
P0307 (M) CYLINDER #7 MISFIRE Misfire detected in cylinder #7
P0308 (M) CYLINDER #8 MISFIRE Misfire detected in cylinder #8.
P0309 (M) CYLINDER #9 MISFIRE Misfire detected in cylinder #9.
P0310 (M) CYLINDER #10 MISFIRE Misfire detected in cylinder #10.
P0320 No Crank Referance Signal at PCM No reference signal (crankshaft position sensor) detected
during engine cranking.
P0325 Knock Sensor #1 Circuit Knock sensor (#1) signal above or below minimum
acceptable threshold voltage at particular engine speeds.
P0330 Knock Sensor #2 Circuit Knock sensor (#2) signal above or below minimum
acceptable threshold voltage at particular engine speeds.
P0340 (M) No Cam Signal At PCM No fuel sync
8E - 12 ELECTRONIC CONTROL MODULESRS
POWERTRAIN CONTROL MODULE (Continued)
ProCarManuals.com

OPERATION - SENSOR RETURN - PCM INPUT
The sensor return circuit provides a low electrical
noise ground reference for all of the systems sensors.
The sensor return circuit connects to internal ground
circuits within the Powertrain Control Module
(PCM).
OPERATION - SCI RECEIVE - PCM INPUT
SCI Receive is the serial data communication
receive circuit for the DRB scan tool. The Powertrain
Control Module (PCM) receives data from the DRB
through the SCI Receive circuit.
OPERATION - IGNITION SENSE - PCM INPUT
The ignition sense input informs the Powertrain
Control Module (PCM) that the ignition switch is in
the crank or run position.
OPERATION - PCM GROUND
Ground is provided through multiple pins of the
PCM connector. Depending on the vehicle there may
be as many as three different ground pins. There are
power grounds and sensor grounds.
The power grounds are used to control the ground
side of any relay, solenoid, ignition coil or injector.
The signal ground is used for any input that uses
sensor return for ground, and the ground side of any
internal processing component.
The SBEC III case is shielded to prevent RFI and
EMI. The PCM case is grounded and must be firmly
attached to a good, clean body ground.
Internally all grounds are connected together, how-
ever there is noise suppression on the sensor ground.
For EMI and RFI protection the case is also
grounded separately from the ground pins.
OPERATION - 8-VOLT SUPPLY - PCM OUTPUT
The PCM supplies 8 volts to the crankshaft posi-
tion sensor, camshaft position sensor.
OPERATION - 5 VOLT SUPPLY - PCM OUTPUT
The PCM supplies 5 volts to the following sensors:
²A/C pressure transducer
²Engine coolant temperature sensor
²Manifold absolute pressure sensor
²Throttle position sensor
²Linear EGR solenoid
OPERATION - MODES OF OPERATION
As input signals to the PCM change, the PCM
adjusts its response to output devices. For example,
the PCM must calculate a different injector pulse
width and ignition timing for idle than it does for
Wide Open Throttle (WOT). There are several differ-
ent modes of operation that determine how the PCM
responds to the various input signals.There are two different areas of operation, OPEN
LOOP and CLOSED LOOP.
During OPEN LOOP modes the PCM receives
input signals and responds according to preset PCM
programming. Inputs from the upstream and down-
stream heated oxygen sensors are not monitored dur-
ing OPEN LOOP modes, except for heated oxygen
sensor diagnostics (they are checked for shorted con-
ditions at all times).
During CLOSED LOOP modes the PCM monitors
the inputs from the upstream and downstream
heated oxygen sensors. The upstream heated oxygen
sensor input tells the PCM if the calculated injector
pulse width resulted in the ideal air-fuel ratio of 14.7
to one. By monitoring the exhaust oxygen content
through the upstream heated oxygen sensor, the
PCM can fine tune injector pulse width. Fine tuning
injector pulse width allows the PCM to achieve opti-
mum fuel economy combined with low emissions.
For the PCM to enter CLOSED LOOP operation,
the following must occur:
(1) Engine coolant temperature must be over 35ÉF.
²If the coolant is over 35É the PCM will wait 44
seconds.
²If the coolant is over 50ÉF the PCM will wait 38
seconds.
²If the coolant is over 167ÉF the PCM will wait
11 seconds.
(2) For other temperatures the PCM will interpo-
late the correct waiting time.
(3) O2 sensor must read either greater than 0.745
volts or less than 0.1 volt.
(4) The multi-port fuel injection systems has the
following modes of operation:
²Ignition switch ON (Zero RPM)
²Engine start-up
²Engine warm-up
²Cruise
²Idle
²Acceleration
²Deceleration
²Wide Open Throttle
²Ignition switch OFF
(5) The engine start-up (crank), engine warm-up,
deceleration with fuel shutoff and wide open throttle
modes are OPEN LOOP modes. Under most operat-
ing conditions, the acceleration, deceleration (with
A/C on), idle and cruise modes,with the engine at
operating temperatureare CLOSED LOOP modes.IGNITION SWITCH ON (ZERO RPM) MODE
When the ignition switch activates the fuel injec-
tion system, the following actions occur:
²The PCM monitors the engine coolant tempera-
ture sensor and throttle position sensor input. The
RSELECTRONIC CONTROL MODULES8E-19
POWERTRAIN CONTROL MODULE (Continued)
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