Chrysler PT Cruiser. Manual - part 471

DIAGNOSIS AND TESTING

DIAGNOSIS AND TESTING - BRAKE/PARK
BRAKE INDICATOR

The brake/park brake indicator illuminates when

the parking brake is applied with the ignition switch
turned to the ON position. The same lamp will also
illuminate if one of the two (hydraulic or ABS) ser-
vice brake systems fail when the brake pedal is
applied.

To test the system:

• As the ignition switch is turned to the START

position the lamp should light.

• Turn ignition switch to the ON position and

apply the parking brake. The lamp should light.

If lamp fails to light inspect for:

• A broken or disconnected wire at the switch

• Defective switch

• A burned out Light Emitting Diode (LED)

• A damaged circuit board
To test the service brake warning system, refer to

Brakes, Diagnosis and Testing, Base Brake System
Diagnosis Charts, Red Brake Warning Lamp.

DIAGNOSIS AND TESTING - CHIME
CONDITIONS

NO TONE WHEN IGNITION SWITCH IS TURNED ON
AND DRIVERS SEAT BELT IS UNBUCKLED

(1) Using an ohmmeter, with the seat belt fully

retracted, check for continuity to ground at Pin 20 of
the 26-way cluster harness connector. If OK, go to
step 2. If not OK, repair as necessary.

(2) Using voltmeter, check for battery feed at Pin 4

of the 26-way cluster harness connector. Check for
ignition feed at Pin 14 of the 26-way cluster harness
connector. If not OK, repair as necessary.

NO FASTEN SEAT BELT LAMP WHEN IGNITION
SWITCH IS ON

(1) Check for battery feed at cluster harness con-

nector Pin 4.

(2) Check for ignition feed at cluster harness con-

nector Pin 14. Repair as necessary.

NO TONE WHEN HEADLAMPS ARE ON AND
DRIVERS DOOR IS OPEN

(1) Remove the key from the ignition.

(2) Check left door jamb switch for good ground

when drivers door is open.

(3) Check for ground at Pin 1 of the 26-way cluster

harness connector.

(4) Check for battery feed at cluster harness con-

nector Pin 4 of the 26-way cluster harness connector.

(5) Check for NO voltage at Pin 14. Ignition volt-

age must not be present for the chime to work.

(6) Check headlamp switch.

NO TONE WHEN KEY IS LEFT IN IGNITION AND
DRIVERS DOOR IS OPEN

(1) Check for continuity to ground at Pin 1 of the

26-way cluster harness connector. If OK, go to Step 4.
If not OK, repair as necessary.

(2) Check pin 19 of the 26-way connector to ground

while pulling key out/in from ignition switch. If not
chime, check ignition switch for problems.

(3) Using voltmeter, check for battery feed at Pin 4

of the 26-way cluster harness connector. Check for
NO ignition feed at Pin 14 of the 26-way cluster har-
ness connector. If OK, go to Step 4. If not OK, repair
as necessary.

(4) Open driver’s door and ensure the ignition key

is in the OFF, LOCK, or ACC position. Check for con-
tinuity to ground at Pin 9 of the 26-way cluster har-
ness connector. If ground OK, replace cluster printed
circuit board. If no ground, check key-in switch or
door switch wiring and repair as necessary.

DIAGNOSIS AND TESTING - FASTEN SEAT
BELTS

To test the fasten seat belts function, turn the igni-

tion switch to the ON position with the driver’s seat
belt unbuckled and fully retracted. The seat belt
warning lamp should light for four to eight seconds
and the tone should sound three to five times.

If the lamp does not light, check the connection at

the seat belt retractor. Replace as necessary.

DIAGNOSIS AND TESTING - KEY IN IGNITION

To test the key left in ignition function, insert key

into the ignition and open the driver’s door. Chime
should sound until key is removed from ignition or
driver’s door is closed.

If these conditions are met and there is still a

problem with the system, refer to Chime System
Conditions in this section for further diagnosis and
testing.

8B - 2

CHIME/BUZZER

CHIME/BUZZER (Continued)

ELECTRONIC CONTROL MODULES

TABLE OF CONTENTS

page

ANTILOCK BRAKE MODULE (MK25E)

DESCRIPTION

. . . . . . . . . . . . . . . . . . . . . . . . . . 1

OPERATION

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

REMOVAL

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

INSTALLATION

. . . . . . . . . . . . . . . . . . . . . . . . . . 2

CONTROLLER ANTILOCK BRAKE (MK20E)

DESCRIPTION

. . . . . . . . . . . . . . . . . . . . . . . . . . 3

OPERATION

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

REMOVAL

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

INSTALLATION

. . . . . . . . . . . . . . . . . . . . . . . . . . 4

DATA LINK CONNECTOR

DESCRIPTION

. . . . . . . . . . . . . . . . . . . . . . . . . . 4

OPERATION

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

HEATED SEAT MODULE

DESCRIPTION

. . . . . . . . . . . . . . . . . . . . . . . . . . 5

OPERATION

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

DIAGNOSIS AND TESTING - HEATED SEAT

MODULE

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

REMOVAL

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

INSTALLATION

. . . . . . . . . . . . . . . . . . . . . . . . . . 6

POWERTRAIN CONTROL MODULE

DESCRIPTION

OPERATION - SENSOR RETURN - PCM

INPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

DATA BUS COMMUNICATION RECEIVE -

PCM INPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

OPERATION - IGNITION SENSE - PCM

INPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

PCM GROUND

. . . . . . . . . . . . . . . . . . . . . . . . 7

OPERATION

. . . . . . . . . . . . . . . . . . . . . . . . . . 7

5 VOLT SUPPLY - PCM OUTPUT

. . . . . . . . . . 11

STANDARD PROCEDURE

STANDARD PROCEDURE - OBTAINING

DIAGNOSTIC TROUBLE CODES . . . . . . . . . . 11

STANDARD PROCEDURE - PINION

FACTOR SETTING . . . . . . . . . . . . . . . . . . . . . 11

STANDARD PROCEDURE - QUICK LEARN

PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . 11

REMOVAL

REMOVAL - 1.6L

. . . . . . . . . . . . . . . . . . . . . . 11

REMOVAL - 2.0, 2.4, and 2.4L Turbo

. . . . . . . 13

INSTALLATION

INSTALLATION - 1.6L

. . . . . . . . . . . . . . . . . . 15

INSTALLATION - 2.0, 2.4, and 2.4L TURBO

. . 15

SENTRY KEY IMMOBILIZER MODULE

DESCRIPTION

. . . . . . . . . . . . . . . . . . . . . . . . . 15

OPERATION

. . . . . . . . . . . . . . . . . . . . . . . . . . . 16

STANDARD PROCEDURE - SENTRY KEY

IMMOBILIZER SYSTEM INITIALIZATION

. . . . 16

REMOVAL

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

INSTALLATION

. . . . . . . . . . . . . . . . . . . . . . . . . 17

ANTILOCK BRAKE MODULE
(MK25E)

DESCRIPTION

The Antilock Brake Module (ABM) is a micropro-

cessor-based device which monitors the antilock
brake system (ABS) during normal braking and con-
trols it when the vehicle is in an ABS stop or when
in a traction control situation. The ABM utilizes a
47-way electrical connector on the vehicle wiring har-

ness. The power source for the ABM is through the
ignition switch in the RUN or ON position.

The ABM is mounted to the HCU as part of the

Integrated Control Unit (ICU) (Fig. 1). The ICU is
located in the engine compartment on the inboard
side of the left body frame rail. For information on
the ICU, (Refer to 5 - BRAKES/HYDRAULIC/ME-
CHANICAL/ICU (INTEGRATED CONTROL UNIT) -
DESCRIPTION).

ELECTRONIC CONTROL MODULES

8E - 1

OPERATION

The primary functions of the Antilock Brake Mod-

ule (ABM) are to:

• monitor the Antilock Brake System (ABS) for

proper operation.

• detect wheel locking or wheel slipping tenden-

cies by monitoring the speed of all four wheels of the
vehicle.

• control fluid modulation to the wheel brakes

while the system is in an ABS mode or the traction
control system is activated.

• store diagnostic information.

• provide communication to the scan tool while in

diagnostic mode.

The ABM constantly monitors the antilock brake

system for proper operation. If the ABM detects a
fault, it will send a message to the mechanical
instrument cluster (MIC) instructing it to turn on the
amber ABS warning indicator lamp and disable the
antilock braking system. The normal base braking
system will remain operational.

The ABM continuously monitors the speed of each

wheel through the signals generated by the wheel
speed sensors to determine if any wheel is beginning
to lock. When a wheel locking tendency is detected,
the ABM commands the ABM command coils to actu-
ate. The ABM command coils then open and close the

valves in the HCU that modulate brake fluid pres-
sure in some or all of the hydraulic circuits. The
ABM continues to control pressure in individual
hydraulic circuits until a locking tendency is no
longer present.

The ABM contains a self-diagnostic program that

monitors the antilock brake system for system faults.
When a fault is detected, the amber ABS warning
indicator lamp is turned on and the fault diagnostic
trouble code (DTC) is then stored in a diagnostic pro-
gram memory. These DTC’s will remain in the ABM
memory even after the ignition has been turned off.
The DTC’s can be read and cleared from the ABM
memory by a technician using a scan tool. If not
cleared with a scan tool, the fault occurrence and
DTC will be automatically cleared from the memory
after the identical fault has not been seen during the
next 3,500 miles of vehicle operation.

ANTILOCK BRAKE MODULE INPUTS

• wheel speed sensors (four)

• brake lamp switch

• ignition switch

• system relay voltage

• ground

• traction control lamp actuation (if equipped)

• diagnostic communication (PCI)

ANTILOCK BRAKE MODULE OUTPUTS

• amber ABS warning indicator lamp actuation

(through MIC)

• red BRAKE warning indicator lamp actuation

(through MIC)

• traction control lamp (if equipped)

• diagnostic communication. (PCI)

REMOVAL

Due to packaging and limited space it is necessary

to remove and disassemble the ICU to service the
Antilock Brake Module on this vehicle. (Refer to 5 -
BRAKES/HYDRAULIC/MECHANICAL/ICU

(INTE-

GRATED CONTROL UNIT) - REMOVAL)

INSTALLATION

Due to packaging and limited space it is necessary

to install the Antilock Brake Module on the HCU,
then install the ICU on the vehicle as an assembly.
(Refer to 5 - BRAKES/HYDRAULIC/MECHANICAL/
ICU (INTEGRATED CONTROL UNIT) - ASSEM-
BLY)

Fig. 1 Mk25e ICU

1 - ANTILOCK BRAKE MODULE (ABM)
2 - HYDRAULIC CONTROL UNIT (HCU)
3 - PUMP/MOTOR

8E - 2

ELECTRONIC CONTROL MODULES

ANTILOCK BRAKE MODULE (MK25E) (Continued)

CONTROLLER ANTILOCK
BRAKE (MK20E)

DESCRIPTION

The controller antilock brake (CAB) is a micropro-

cessor-based device which monitors the ABS system
during normal braking and controls it when the vehi-
cle is in an ABS stop. The CAB uses a 24-way elec-
trical connector on the vehicle wiring harness. The
power source for the CAB is through the ignition
switch in the RUN or ON position. The CAB is on
the PCI bus.

The CAB is mounted to the HCU as part of the

Integrated Control Unit (ICU) (Fig. 2). Attached to
the bottom of the HCU, it can be viewed from below,
just above the transaxle and left halfshaft (Fig. 3).
For information on the ICU, (Refer to 5 - BRAKES/
HYDRAULIC/MECHANICAL/ICU

(INTEGRATED

CONTROL UNIT) - DESCRIPTION)

OPERATION

The primary functions of the controller antilock

brake (CAB) are to:

• monitor the antilock brake system for proper

operation.

• detect wheel locking or wheel slipping tenden-

cies by monitoring the speed of all four wheels of the
vehicle.

• control fluid modulation to the wheel brakes

while the system is in an ABS mode or the traction
control system is activated.

• store diagnostic information.

• provide communication to the DRBIIIt scan tool

while in diagnostic mode.

The CAB constantly monitors the antilock brake

system for proper operation. If the CAB detects a
fault, it will send a message to the mechanical
instrument cluster (MIC) instructing it to turn on the
amber ABS warning indicator lamp and disable the
antilock braking system. The normal base braking
system will remain operational.

The CAB continuously monitors the speed of each

wheel through the signals generated by the wheel
speed sensors to determine if any wheel is beginning
to lock. When a wheel locking tendency is detected,
the CAB commands the CAB command coils to actu-
ate. The CAB command coils then open and close the
valves in the HCU that modulate brake fluid pres-
sure in some or all of the hydraulic circuits. The CAB
continues to control pressure in individual hydraulic
circuits until a locking tendency is no longer present.

The CAB contains a self-diagnostic program that

monitors the antilock brake system for system faults.
When a fault is detected, the amber ABS warning
lamp is turned on and the fault diagnostic trouble
code (DTC) is then stored in a diagnostic program
memory. These DTC’s will remain in the CAB mem-
ory even after the ignition has been turned off. The
DTC’s can be read and cleared from the CAB mem-
ory by a technician using the DRB scan tool. If not
cleared with a DRB scan tool, the fault occurrence
and DTC will be automatically cleared from the CAB
memory after the identical fault has not been seen
during the next 3,500 miles of vehicle operation.

CONTROLLER ANTILOCK BRAKE INPUTS

• wheel speed sensors (four)

• brake lamp switch

• ignition switch

Fig. 2 Integrated Control Unit (ICU)

1 - PUMP/MOTOR
2 - HCU
3 - PUMP/MOTOR WIRING CONNECTOR
4 - CAB

Fig. 3 CAB Location In Vehicle

1 - TRANSAXLE
2 - HCU
3 - LEFT HALFSHAFT
4 - CAB

ELECTRONIC CONTROL MODULES

8E - 3

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