When diagnosing a chassis system problem, it is
important to follow approved procedures where
applicable. These procedures can be found in this
General Information Section or in the service man-
ual procedures. Following these procedures is very
important to safety of individuals performing diag-
nostic tests.
4.2.2 VEHICLE PREPARATION FOR
TESTING
Make sure the vehicle being tested has a fully
charged battery. If it does not, false diagnostic codes
or error messages may occur.
4.2.3 SERVICING SUB-ASSEMBLIES
Some components of the chassis system are in-
tended to be serviced as an assembly only. Attempt-
ing to remove or repair certain system sub-
components may result in personal injury and/or
improper system operation. Only those components
with approved repair and installation procedures in
the service manual should be serviced.
4.2.4 DRBIIITSAFETY INFORMATION
WARNING: EXCEEDING THE LIMITS OF THE
DRBIIITMULTIMETER IS DANGEROUS. IT
CAN EXPOSE YOU TO SERIOUS OR
POSSIBLY FATAL INJURY. CAREFULLY
READ AND UNDERSTAND THE CAUTIONS
AND THE SPECIFICATION LIMITS.
²Follow the vehicle manufacturer 's service speci-
fications at all times.
²Do not use the DRBIIItif it has been damaged.
²Do not use the test leads if the insulation is
damaged or if metal is exposed.
²To avoid electrical shock, do not touch the test
leads, tips, or the circuit being tested.
²Choose the proper range and functions for the
measurement. Do not try voltage or current mea-
surement that may exceed the rated capacity.
²Do not exceed the limits shown in the table below:
FUNCTION INPUT LIMIT
Volts 0 - 500 peak volts AC
0 - 500 volts DC
Ohms (resistance)* 0 -1.12 megohms
Frequency Measured
Frequency Generated0-10kHz
Temperature -58 - 1100ÉF
-50 - 600ÉC* Ohms cannot be measured if voltage is present.
Ohms can be measured only in a non-powered
circuit.
²Voltage between any terminal and ground must
not exceed 500v DC or 500v peak AC.
²Use caution when measuring voltage above 25v
DC or 25v AC.
²Use the low current shunt to measure circuits up
to 10A. Use the high current clamp to measure
circuits exceeding 10A.
²When testing for the presence of voltage or cur-
rent, make sure the meter is functioning cor-
rectly. Take a reading of a known voltage or
current before accepting a zero reading.
²When measuring current, connect the meter in
series with the load.
²Disconnect the live test lead before disconnecting
the common test lead.
²When using the meter function, keep the
DRBIIItaway from spark plug or coil wires to
avoid measuring error from outside interference.
4.3 WARNINGS
4.3.1 VEHICLE DAMAGE WARNINGS
Before disconnecting any control module, make
sure the ignition is ªoffº. Failure to do so could
damage the module.
When testing voltage or continuity at any control
module, use the terminal side (not the wire end) of
the connector. Do not probe a wire through the
insulation; this will damage it and eventually cause
it to fail because of corrosion. Be careful when
performing electrical tests so as to prevent acciden-
tal shorting of terminals. Such mistakes can dam-
age fuses or components. Also, a second code could
be set, making diagnosis of the original problem
more difficult.
4.3.2 ROAD TESTING A COMPLAINT
VEHICLE
Some complaints will require a test drive as part
of the repair verification procedure. The purpose of
the test drive is to try to duplicate the diagnostic
code or symptom condition.
29
GENERAL INFORMATION
4.0 DISCLAIMERS, SAFETY,
WARNINGS
4.1 DISCLAIMERS
All information, illustrations, and specifications
contained in this manual are based on the latest
information available at the time of publication.
The right is reserved to make changes at any time
without notice.
4.2 SAFETY
4.2.1 TECHNICIAN SAFETY INFORMATION
WARNING: ENGINES PRODUCE CARBON
MONOXIDE THAT IS ODORLESS, CAUSES
SLOWER REACTION TIME, AND CAN LEAD
TO SERIOUS INJURY. WHEN THE ENGINE IS
OPERATING, KEEP SERVICE AREAS WELL
VENTILATED OR ATTACH THE VEHICLE
EXHAUST SYSTEM TO THE SHOP EXHAUST
REMOVAL SYSTEM.
Set the parking brake and block the wheels before
testing or repairing the vehicle. It is especially
important to block the wheels on front-wheel drive
vehicles; the parking brake does not hold the drive
wheels.
When servicing a vehicle, always wear eye pro-
tection, and remove any metal jewelry such as
rings, watchbands or bracelets that might make an
inadvertent electrical contact.
When diagnosing a chassis problem, it is impor-
tant to follow approved procedures where applica-
ble. These procedures can be found in the service
manual. Following these procedures is very impor-
tant to the safety of individuals performing diag-
nostic tests.
4.2.2 VEHICLE PREPARATION FOR
TESTING
Make sure the vehicle being tested has a fully
charged battery. If is does not, false diagnostic codes
or error messages may occur.
4.2.3 SERVICING SUB-ASSEMBLIES
Some components of the chassis system are in-
tended to be serviced as an assembly only. Attempt-
ing to remove or repair certain system sub-
components may result in personal injury and/or
improper system operation. Only those components
with approved repair and installation procedures in
the service manual should be serviced.
4.2.4 DRBIIITSAFETY INFORMATION
WARNING: EXCEEDING THE LIMITS OF THE
DRB MULTIMETER IS DANGEROUS. IT CAN
EXPOSE YOU TO SERIOUS OR POSSIBLY
FATAL INJURY. CAREFULLY READ AND
UNDERSTAND THE CAUTIONS AND THE
SPECIFICATION LIMITS.
²Follow the vehicle manufacturer 's service speci-
fications at all times.
²Do not use the DRBIIItif it has been damaged.
²Do not use the test leads if the insulation is
damaged or if metal is exposed.
²To avoid electrical shock, do not touch the test
leads, tips, or the circuit being tested.
²Choose the proper range and functions for the
measurement. Do not try voltage or current mea-
surements that may exceed the rated capacity.
²Do not exceed the limits shown in the table below:
FUNCTION INPUT LIMIT
Volts 0 - 500 peak volts AC
0 - 500 volts DC
Ohms (resistance)* 0 -1.12 megohms
Frequency Measured
Frequency Generated0-10kHz
Temperature -58 - 1100ÉF
-50 - 600ÉC
* Ohms cannot be measured if voltage is present.
Ohms can be measured only in a non-powered
circuit.
²Voltage between any terminal and ground must
not exceed 500v DC or 500v peak AC.
²Use caution when measuring voltage above 25v
DC or 25v AC.
²Use the low current shunt to measure circuits up
to 10A. Use the high current clamp to measure
circuits exceeding 10A.
²When testing for the presence of voltage or cur-
rent, make sure the meter is functioning cor-
rectly. Take a reading of a known voltage or
current before accepting a zero reading.
²When measuring current, connect the meter in
series with the load.
²Disconnect the live test lead before disconnecting
the common test lead.
²When using the meter function, keep the
DRBIIItaway from spark plug or coil wires to
avoid measuring error from outside interference.
5
GENERAL INFORMATION
4.0 DISCLAIMERS, SAFETY,
WARNINGS
4.1 DISCLAIMERS
All information, illustrations, and specifications
contained in this manual are based on the latest
information available at the time of publication.
The right is reserved to make changes at any time
without notice.
4.2 SAFETY
4.2.1 TECHNICIAN SAFETY INFORMATION
WARNING: ENGINES PRODUCE CARBON
MONOXIDE THAT IS ODORLESS, CAUSES
SLOWER REACTION TIME, AND CAN LEAD
TO SERIOUS INJURY. WHEN THE ENGINE IS
OPERATING, KEEP SERVICE AREAS WELL
VENTILATED OR ATTACH THE VEHICLE
EXHAUST SYSTEM TO THE SHOP EXHAUST
REMOVAL SYSTEM.
Set the parking brake and block the wheels before
testing or repairing the vehicle. It is especially
important to block the wheels on front wheel drive
vehicles; the parking brake does not hold the drive
wheels.
When servicing a vehicle, always wear eye pro-
tection, and remove any metal jewelry such as
watchbands or bracelets that might make electrical
contact.
When diagnosing a powertrain system problem,
it is important to follow approved procedures where
applicable. These procedures can be found in the
service manual. Following these procedures is very
important to the safety of individuals performing
diagnostic tests.
4.2.2 VEHICLE PREPARATION FOR
TESTING
Make sure the vehicle being tested has a fully
charged battery. If it does not, false diagnostic codes
or error messages may occur.
4.2.3 SERVICING SUB-ASSEMBLIES
Some components of the powertrain system are
intended to be serviced as an assembly only. At-
tempting to remove or repair certain system sub-
components may result in personal injury and/or
improper system operation. Only those components
with approved repair and installation procedures in
the service manual should be serviced.
4.2.4 DRBIIITSAFETY INFORMATION
WARNING: EXCEEDING THE LIMITS OF THE
DRBIIITMULTIMETER IS DANGEROUS. IT
CAN EXPOSE YOU TO SERIOUS OR
POSSIBLY FATAL INJURY. CAREFULLY
READ AND UNDERSTAND THE CAUTIONS
AND SPECIFICATION LIMITS.
Follow the vehicle manufacturer 's service specifi-
cations at all times.
²Do not use the DRBIIItif it has been damaged.
²Do not use the test leads if the insulation is
damaged or if metal is exposed.
²To avoid electrical shock, do not touch the test
leads, tip or the circuit being tested.
²Choose the proper range and function for the
measurement. Do not try voltage or current mea-
surements that may exceed the rated capacity.
²Do not exceed the limits shown in the table below:
FUNCTION INPUT LIMIT
Volts 0-500 peak volts AC
0-500 volts DC
Ohms (Resistance)* 0-1.12 megohms
Frequency Measure
Frequency Generated0-10 kHz
Temperature -58 - +1100ÉF
-50 - +600ÉC
* Ohms cannot be measured if voltage is present.
Ohms can be measured only in a non-powered
circuit.
²Voltage between any terminal and ground must
not exceed 500v DC or 500v peak AC.
²Use caution when measuring voltage above 25v
DC or 25v AC.
²The circuit being tested must be protected by a 10
amp fuse or circuit breaker.
²Use the low current shunt to measure circuits up
to 10 amps. Use the high current shunt to mea-
sure circuits exceeding 10 amps.
²When testing for the presence of voltage or cur-
rent, make sure the meter is functioning cor-
rectly. Take a reading of a known voltage or
current before accepting a zero reading.
²When measuring current, connect the meter in
series with the load.
²Disconnect the live test lead before disconnecting
the common test lead.
7
GENERAL INFORMATION
Symptom List:
P0560-SYSTEM VOLTAGE TOO LOW
*CHECKING THE CHARGING SYSTEM OPERATION - DIESEL
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P0560-SYSTEM VOLTAGE TOO
LOW.
When Monitored and Set Condition:
P0560-SYSTEM VOLTAGE TOO LOW
When Monitored: With the engine running.
Set Condition: The ECM detects the system voltage at least 0.5 volt below the target
charging voltage for at least 3 seconds.
POSSIBLE CAUSES
CHECK FOR CYCLING VOLTAGE ON THE GENERATOR FIELD DRIVER CIRCUIT
INTERMITTENT CONDITION
GENERATOR BELT CONDITION OR TENSION
HIGH RESISTANCE IN THE FUEL HEATER RELAY OUTPUT CIRCUIT TO THE ECM
GENERATOR FIELD DRIVER CIRCUIT SHORTED TO VOLTAGE
GENERATOR FUSED B+ CIRCUIT HIGH RESISTANCE
ECM/PCM RELAY OUTPUT CIRCUIT OPEN
GENERATOR GROUND CIRCUIT HIGH RESISTANCE
GENERATOR FIELD DRIVER CIRCUIT OPEN
ENGINE CONTROL MODULE
TEST ACTION APPLICABILITY
1NOTE: If there are any Battery Sense DTCs (P1511 or P1512) present with
this DTC, diagnose the Battery Sense DTCs first.
NOTE: Inspect the vehicle for aftermarket accessories that may exceed the
Generator capacity.
NOTE: The battery must be fully charged before continuing.
Inspect the generator belt condition and tension.
Is the generator belt in good condition and tensioned properly?All
Ye s®Go To 2
No®Repair as necessary.
Perform CHARGING VERIFICATION - VER-3.
120
DRIVEABILITY - DIESEL
CAUTION: The master cylinder (and its rear seal) is
used to create the seal for holding vacuum in the
vacuum booster. The vacuum seal on the master
cylinder MUST be replaced with a NEW seal when-
ever the master cylinder is removed from the vac-
uum booster.
CAUTION: When removing the vacuum seal from
the master cylinder do not use a sharp tool.
(8) Using a soft tool such as a trim stick, remove
the vacuum seal from the master cylinder mounting
flange.
(9) Install a NEW vacuum seal on rear mounting
flange of the master cylinder (Fig. 60).
(10) Position master cylinder on studs of booster,
aligning push rod on booster with master cylinder
piston.
(11) Install the two nuts mounting the master cyl-
inder to the booster (Fig. 55). Tighten both mounting
nuts to a torque of 25 N´m (225 in. lbs.).
(12) Connect wiring harness connector to brake
fluid level switch in the master cylinder fluid reser-
voir (Fig. 54).
(13) Connect primary and secondary brake tubes
to ABS ICU or non-ABS junction block (Fig. 55).
Tighten the tube nuts to 17 N´m (145 in lbs.).
(14) Install wiper module (unit). (Refer to 8 -
ELECTRICAL/WIPERS/WASHERS/WIPER MOD-
ULE - INSTALLATION)
(15) If equipped with speed control, install speed
control servo and connect wiring connector. Tighten
the mounting nuts to a torque of 14 N´m (124 in.
lbs.).(16) Install the battery tray. Install the two nuts
and one bolt attaching the battery tray to the vehicle.
Tighten the bolt and nuts to a torque of 14 N´m (124
in. lbs.).
(17) If vehicle is equipped with speed control, con-
nect the servo vacuum hose to the vacuum tank on
the battery tray.
(18) Install the air inlet resonator and hoses as an
assembly on the throttle body and air cleaner hous-
ing. Securely tighten hose clamp at air cleaner hous-
ing and throttle body.
(19) Secure the engine coolant filler neck to the
battery tray with its mounting screw.
(20) Install the battery, clamp and mounting nut.
(21) Install the positive battery cable on the bat-
tery.
(22) Install the negative battery cable on the bat-
tery.
(23) Install the battery thermal guard shield.
(24) Bleed the base brakes as necessary. (Refer to
5 - BRAKES - STANDARD PROCEDURE)
(25) Road test vehicle to ensure operation of the
brakes.
PROPORTIONING VALVE
DESCRIPTION - PROPORTIONING VALVE
(HEIGHT SENSING)
NOTE: Only vehicles without antilock brakes (ABS)
have a proportioning valve. Vehicles with ABS uti-
lize electronic brake distribution which is controlled
through the ABS integrated control unit.
Vehicles not equipped with ABS use a height sens-
ing proportioning valve. It is mounted to the body of
the vehicle above the rear axle (Fig. 61). It has an
actuator lever that attaches to the rear axle and
moves with the axle to help the valve sense the vehi-
cle height.
CAUTION: The height sensing proportioning valve
is not adjustable. No attempt should be made to
adjust it. It is replaced as a complete assembly.
CAUTION: The use of after-market load leveling or
load capacity increasing devices on this vehicle are
prohibited. Using air shock absorbers or helper
springs on this vehicle will cause the height sens-
ing proportioning valve to inappropriately reduce
the hydraulic pressure to the rear brakes. This inap-
propriate reduction in hydraulic pressure potentially
could result in increased stopping distance of the
vehicle.
Fig. 60 Vacuum Seal (Typical)
1 - MASTER CYLINDER ASSEMBLY
2 - VACUUM SEAL
RSBRAKES - BASE5-41
POWER BRAKE BOOSTER (Continued)
BATTERY SYSTEM DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
THE BATTERY SEEMS
WEAK OR DEAD WHEN
ATTEMPTING TO START
THE ENGINE.1. The battery has an
incorrect size or rating for
this vehicle.1. Refer to Battery Specifications for the proper
size and rating. Replace an incorrect battery, as
required.
2. The battery is physically
damaged.2. Inspect the battery for loose terminal posts or a
cracked and leaking case. Replace the damaged
battery, as required.
3. The battery terminal
connections are loose or
corroded.3. Refer to Battery Cable for the proper cable
diagnosis and testing procedures. Clean and
tighten the battery terminal connections, as
required.
4. The battery is discharged. 4. Determine the battery state-of-charge. Refer to
Standard Procedures for the proper test
procedures. Charge the faulty battery, as
required.
5. The electrical system
ignition-off draw is excessive.5. Refer to Standard Procedures for the proper
test procedures. Repair the faulty electrical
system, as required.
6. The battery is faulty. 6. Determine the battery cranking capacity. Refer
to Standard Procedures for the test procedures.
Replace the faulty battery, as required.
7. The starting system is
faulty.7. Determine if the starting system is performing
to specifications. Refer to Starting System for the
proper starting system diagnosis and testing
procedures. Repair the faulty starting system, as
required.
8. The charging system is
faulty.8. Determine if the charging system is performing
to specifications. Refer to Charging System for
the proper charging system diagnosis and testing
procedures. Repair the faulty charging system, as
required.
RSBATTERY SYSTEM8F-3
BATTERY SYSTEM (Continued)
BATTERY SYSTEM DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
THE BATTERY STATE OF
CHARGE CANNOT BE
MAINTAINED.1. The battery has an
incorrect size or rating for
this vehicle.1. Refer to Battery Specifications for the proper
specifications. Replace an incorrect battery, as
required.
2. The battery terminal
connections are loose or
corroded.2. Refer to Battery Cable for the proper cable
diagnosis and testing procedures. Clean and
tighten the battery terminal connections, as
required.
3. The generator drive belt is
slipping.3. Refer to Cooling System for the proper
accessory drive belt diagnosis and testing
procedures. Replace or adjust the faulty
generator drive belt, as required.
4. The electrical system
ignition-off draw is excessive.4. Refer to Standard Procedures for the proper
test procedures. Repair the faulty electrical
system, as required.
5. The battery is faulty. 5. Determine the battery cranking capacity. Refer
to Standard Procedures for the proper test
procedures. Replace the faulty battery, as
required.
6. The starting system is
faulty.6. Determine if the starting system is performing
to specifications. Refer to Starting System for the
proper starting system diagnosis and testing
procedures. Repair the faulty starting system, as
required.
7. The charging system is
faulty.7. Determine if the charging system is performing
to specifications. Refer to Charging System for
the proper charging system diagnosis and testing
procedures. Repair the faulty charging system, as
required.
8. Electrical loads exceed the
output of the charging
system.8. Inspect the vehicle for aftermarket electrical
equipment which might cause excessive electrical
loads.
9. Slow driving or prolonged
idling with high-amperage
draw systems in use.9. Advise the vehicle operator, as required.
THE BATTERY WILL NOT
ACCEPT A CHARGE.1. The battery is faulty. 1. Refer to Standard Procedures for the proper
battery charging procedures. Charge or replace
the faulty battery, as required.
ABNORMAL BATTERY DISCHARGING
Any of the following conditions can result in abnor-
mal battery discharging:
²Corroded or loose battery posts and terminal
clamps.
²A loose or worn generator drive belt.
²Electrical loads that exceed the output of the
charging system. This can be due to equipment
installed after manufacture, or repeated short trip
use.²Slow driving speeds (heavy traffic conditions) or
prolonged idling, with high-amperage draw systems
in use.
²A faulty circuit or component causing excessive
ignition-off draw.
²A faulty or incorrect charging system compo-
nent. Refer to Charging System for the proper charg-
ing system diagnosis and testing procedures.
8F - 4 BATTERY SYSTEMRS
BATTERY SYSTEM (Continued)
(2) Inspect the battery tray and battery holddown
hardware for damage. Replace any damaged parts.
(3) Slide the thermal guard off of the battery case.
Inspect the battery case for cracks or other damage
that could result in electrolyte leaks. Also, check the
battery terminal posts for looseness. Batteries with
damaged cases or loose terminal posts must be
replaced.
(4) Inspect the battery thermal guard for tears,
cracks, deformation or other damage. Replace any
battery thermal guard that has been damaged.
(5) Inspect the electrolyte level in the battery. Use
a putty knife or another suitable wide flat-bladed tool
to pry the cell caps off (Fig. 4).DO NOT USE A
SCREWDRIVER.Add distilled water to each bat-
tery cell until the liquid reaches the bottom of the
vent well or one centimeter above the battery plates.
DO NOT OVERFILL THE BATTERY CELLS.
(6) Inspect the battery built-in test indicator sight
glass for an indication of the battery condition. If the
battery is discharged, charge as required. Refer to
Standard Procedures for the proper battery built-in
indicator test procedures. Also refer to Standard Pro-
cedures for the proper battery charging procedures.
BATTERY
BATTERY
DESCRIPTION
A large capacity, low-maintenance storage battery
(Fig. 5) is standard factory-installed equipment on this
model. Male post type terminals made of a soft lead
Fig. 3 Clean Battery Terminal Post - Typical
1 - TERMINAL BRUSH
2 - BATTERY CABLE
3 - BATTERY
Fig. 4 Removing Battery Cell Caps - Typical
1 - PUTTY KNIFE
Fig. 5 Low-Maintenance Battery - Typical
1 - POSITIVE POST
2 - VENT
3 - CELL CAP
4 - TEST INDICATOR
5 - CELL CAP
6 - VENT
7 - NEGATIVE POST
8 - GREEN BALL
9 - ELECTROLYTE LEVEL
10 - PLATE GROUPS
11 - LOW-MAINTENANCE BATTERY
8F - 6 BATTERY SYSTEMRS
BATTERY SYSTEM (Continued)