
Symptom:
B1802 POWER SUPPLY OUT OF RANGE: VOLTAGE ABOVE 15.5
VOLTS
When Monitored and Set Condition:
B1802 POWER SUPPLY OUT OF RANGE: VOLTAGE ABOVE 15.5 VOLTS
When Monitored: With the engine running.
Set Condition: This DTC will set if the DCHA's power supply voltage exceeds 15.5 volts
for longer than six seconds.
POSSIBLE CAUSES
VEHICLE'S CHARGING SYSTEM OVERCHARGING
DCHA CONTROL UNIT FAULT
TEST ACTION APPLICABILITY
1WARNING: DO NOT OPERATE THE DCHA IN AN ENCLOSED AREA SUCH
AS A GARAGE THAT DOES NOT HAVE EXHAUST VENTILATION FACILI-
TIES. ALWAYS VENT THE DCHA's EXHAUST WHEN OPERATING THE
DCHA. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN
PERSONAL INJURY OR DEATH.
WARNING: ALLOW THE DCHA ASSEMBLY TO COOL BEFORE PERFORM-
ING A COMPONENT INSPECTION/REPAIR/REPLACEMENT. FAILURE TO
FOLLOW THESE INSTRUCTIONS MAY RESULT IN PERSONAL INJURY.
CAUTION: DO NOT PERFORM THIS TEST UNLESS DIRECTED HERE BY
THE CABIN HEATER PRE-TEST. ALWAYS PERFORM THE CABIN HEATER
PRE-TEST PRIOR TO PERFORMING ANY OTHER CABIN HEATER TEST
FOR THE RESULT TO BE VALID.
Check the vehicle's charging system for proper operation in accordance with the
Service Information.
Is the vehicle's charging system operating properly?All
Ye s®Replace the DCHA Heater Module in accordance with the Service
Information.
Perform CABIN HEATER VERIFICATION TEST - VER 1.
No®Repair the vehicle's charging system in accordance with the
Service Information.
Perform CABIN HEATER VERIFICATION TEST - VER 1.
307
CABIN HEATER

Symptom:
CHARGING VOLTAGE HIGH MESSAGE
When Monitored and Set Condition:
CHARGING VOLTAGE HIGH MESSAGE
When Monitored: During cranking or with the engine running.
Set Condition: When the Memory Seat Mirror Module receives three high charging
system voltage messages above 15.94 volts over the PCI Bus. Code will remain for 50
ignition cycles.
POSSIBLE CAUSES
PCM TROUBLE CODES
STORED CODE COMMUNICATION PROBLEMS
MEMORY SEAT MIRROR MODULE
INTERMITTENT PROBLEM
TEST ACTION APPLICABILITY
1 Turn ignition on.
With the DRBIIItread Engine DTCs.
Is the DTC P1594 Charging System Voltage Too High set in the Power Control
Module?All
Ye s®Refer to symptom *P1594-CHARGING SYSTEM VOLTAGE TOO
HIGH in the CHARGING category
Perform MEMORY SYSTEM VERIFICATION TEST - VER 1.
No®Go To 2
2 With the DRBIIIt, erase the DTC from Memory Seat Mirror Module.
Turn the ignition switch to the Off position then start the engine and let run for one
minute.
With the DRB check for the same DTC to reset in the MSMM.
Did the same DTC reset?All
Ye s®Go To 3
No®Test complete.
Perform MEMORY SYSTEM VERIFICATION TEST - VER 1.
3Note: Visually inspect the related wiring harness. Look for any chafed,
pierced, pinched, or partially broken wires.
Note: Visually inspect the related wiring harness connectors. Look for
broken, bent, pushed out, or corroded terminals.
Note: Refer to any technical service bulletins that may apply.
Were any problems found?All
No®Replace the Memory Seat Mirror Module.
Perform MEMORY SYSTEM VERIFICATION TEST - VER 1.
Ye s®Repair as necessary.
Perform MEMORY SYSTEM VERIFICATION TEST - VER 1.
643
MEMORY SEAT

Symptom:
CHARGING VOLTAGE LOW MESSAGE
When Monitored and Set Condition:
CHARGING VOLTAGE LOW MESSAGE
When Monitored: During cranking or with the engine running.
Set Condition: When the Memory Seat Mirror Module receives three low charging system
voltage messages below 9 volts over the PCI Bus. Code will remain for 50 ignition cycles.
POSSIBLE CAUSES
PCM TROUBLE CODES
STORED CODE COMMUNICATION PROBLEMS
MEMORY SEAT MIRROR MODULE
INTERMITTENT PROBLEM
TEST ACTION APPLICABILITY
1 Turn ignition on.
With the DRBIIItread Engine DTCs.
Is the DTC P1682 Charging System Voltage Too Low set in the Power Control
Module?All
Ye s®Refer to symptom *P1682-CHARGING SYSTEM VOLTAGE TOO
LOW in the CHARGING category
Perform MEMORY SYSTEM VERIFICATION TEST - VER 1.
No®Go To 2
2 With the DRBIIIt, erase the DTC from Memory Seat Mirror Module.
Turn the ignition switch to the Off position then start the engine and let run for one
minute.
With the DRB check for the same DTC to reset in the MSMM.
Did the same DTC reset?All
Ye s®Go To 3
No®Test complete.
Perform MEMORY SYSTEM VERIFICATION TEST - VER 1.
3Note: Visually inspect the related wiring harness. Look for any chafed,
pierced, pinched, or partially broken wires.
Note: Visually inspect the related wiring harness connectors. Look for
broken, bent, pushed out, or corroded terminals.
Note: Refer to any technical service bulletins that may apply.
Were any problems found?All
No®Replace the Memory Seat Mirror Module.
Perform MEMORY SYSTEM VERIFICATION TEST - VER 1.
Ye s®Repair as necessary.
Perform MEMORY SYSTEM VERIFICATION TEST - VER 1.
644
MEMORY SEAT

TEST ACTION APPLICABILITY
3 Turn the ignition off.
Disconnect the CAB connector.
Note: Check connector - Clean/repair as necessary.
Start the engine.
Raise engine speed above 1,800 RPM.
Measure the battery voltage.
Is the voltage above 16.5 volts ?All
Ye s®Refer to appropriate service information for charging system
testing and repair.
Perform ABS VERIFICATION TEST - VER 1.
No®Go To 4
4 Turn the ignition off.
Disconnect the CAB connector.
Note: Check connector - Clean/repair as necessary.
Measure the resistance of the ground circuits.
Is the resistance below 1.0 ohm?All
Ye s®Go To 5
No®Repair the Ground circuit for an open.
Perform ABS VERIFICATION TEST - VER 1.
5 If there are no potential causes remaining, view repair. All
Repair
Replace the Controller Antilock Brake.
Perform ABS VERIFICATION TEST - VER 1.
6 Turn the ignition off.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wire harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Refer to any Hotline letters or Technical Service Bulletins that may apply.
Were any problems found?All
Ye s®Repair as necessary.
Perform ABS VERIFICATION TEST - VER 1.
No®Test Complete.
29
BRAKES (CAB)
SYSTEM OVERVOLTAGE ÐContinued

Symptom:
SYSTEM UNDERVOLTAGE
When Monitored and Set Condition:
SYSTEM UNDERVOLTAGE
When Monitored: Ignition on. The CAB monitors the Fused Ignition Switch Output
circuit voltage above 10 km/h (6 mph) every 7 milliseconds for proper system voltage.
Set Condition: If the voltage is below 9.5 volts, the Diagnostic Trouble Code (DTC) is set.
POSSIBLE CAUSES
BATTERY VOLTAGE LOW
INTERMITTENT DTC
FUSED IGNITION SWITCH OUTPUT CIRCUIT HIGH RESISTANCE
CAB - INTERNAL FAULT
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, erase DTC's.
Turn the ignition off.
Turn the ignition on.
Start the engine.
Drive the vehicle above 16 km/h (10 mph) for at least 20 seconds.
Stop the vehicle
With the DRBIIIt, read DTC's.
Does the DRBIIItdisplay System Undervoltage DTC?All
Ye s®Go To 2
No®Go To 5
2 Engine Running.
Measure the battery voltage.
Is the battery voltage below 10 volts?All
Ye s®Refer to appropriate service information for charging system
testing and repair.
Perform ABS VERIFICATION TEST - VER 1.
No®Go To 3
3 Disconnect the CAB harness connector.
Turn the ignition on.
Measure the voltage of the Fused Ignition Switch circuit.
Is the voltage above 10 volts?All
Ye s®Go To 4
No®Repair the Fused Ignition Switch Output Circuit for high resis-
tance
Perform ABS VERIFICATION TEST - VER 1.
30
BRAKES (CAB)

TABLE OF CONTENTS - Continued
P0235-BOOST PRESSURE SENSOR SIGNAL VOLTAGE TOO LOW.............67
P0235-BOOST PRESSURE SENSOR SUPPLY VOLTAGE TOO HIGH OR LOW....70
P0335-CKP POSITION SENSOR CIRCUIT OVERSPEED RECOGNITION.........73
P0340-CKP POSITION SENSOR CIRCUIT DYNAMIC PLAUSIBILITY.............75
P0340-CMP POSITION SENSOR CIRCUIT CMP/CKP SYNC FAILURE...........77
P0340-CMP POSITION SENSOR CIRCUIT SIGNAL FREQUENCY TOO HIGH.....80
P0340-CMP POSITION SENSOR CIRCUIT STATIC PLAUSIBILITY...............80
P0380-GLOW PLUG CIRCUIT A OPEN CIRCUIT.............................84
P0380-GLOW PLUG CIRCUIT A SHORT CIRCUIT............................84
P0403-EGR SOLENOID CIRCUIT OPEN CIRCUIT............................87
P0403-EGR SOLENOID CIRCUIT SHORT CIRCUIT...........................90
P0480-FAN 1 CONTROL CIRCUIT OPEN CIRCUIT...........................92
P0480-FAN 1 CONTROL CIRCUIT SHORT CIRCUIT..........................94
P0481-FAN 2 CONTROL CIRCUIT OPEN CIRCUIT...........................96
P0481-FAN 2 CONTROL CIRCUIT SHORT CIRCUIT..........................98
P0500-VEHICLE SPEED SENSOR FREQUENCY TOO HIGH..................100
P0500-VEHICLE SPEED SENSOR HIGH LEVEL DURATION...................100
P0500-VEHICLE SPEED SENSOR PLAUSIBILITY...........................100
P0500-VEHICLE SPEED SENSOR SIGNAL VOLTAGE TOO HIGH..............100
P0514-BATTERY TEMP SENSOR CIRCUIT SIGNAL VOLTAGE TOO HIGH.......104
P0520- OIL PRESS SENSOR CIRCUIT MALF PLAUSIBILITY..................107
P0520-OIL PRESS SENSOR CKT MALF SUPPLY VOLTAGE TOO HIGH OR LOW .110
P0530-A/C PRESSURE SENSOR CIRCUIT PLAUSIBILITY....................112
P0530-A/C PRESSURE SENSOR CIRCUIT SIGNAL VOLTAGE TOO HIGH.......112
P0530-A/C PRESSURE SENSOR CIRCUIT SIGNAL VOLTAGE TOO LOW.......112
P0530-A/C PRESSURE SENSOR CIRCUIT SUPPLY VOLTAGE TOO HIGH OR
LOW.................................................................112
P0560-SYSTEM VOLTAGE TOO HIGH.....................................117
P0560-SYSTEM VOLTAGE TOO LOW.....................................120
*CHECKING THE CHARGING SYSTEM OPERATION - DIESEL................120
P0615-STARTER RELAY CIRCUIT SHORT CIRCUIT.........................124
P0620-GENERATOR FIELD CONTROL MALF BATTERY VOLTAGE
DEVIATION TOO HIGH.................................................126
P0620-GENERATOR FIELD CONTROL MALF BATTERY VOLTAGE
DEVIATION TOO LOW..................................................126
P0620-GENERATOR FIELD CONTROL MALF BATTERY VOLTAGE TOO HIGH . . .126
P0620-GENERATOR FIELD CONTROL MALF BATTERY VOLTAGE TOO LOW. . . .126
P0620-GENERATOR FIELD CONTROL MALF CHARGING VOLTS TOO LOW. . . .126
P0620-GENERATOR FIELD CONTROL MALF OPEN CIRCUIT.................126
P0620-GENERATOR FIELD CONTROL MALF SHORT CIRCUIT................126
P0620-GENERATOR FIELD CONTROL MALF UNSTABLE CURRENT...........126
P0627-FUEL LIFT PUMP RELAY CONTROL CIRCUIT OPEN CIRCUIT..........129
P0627-FUEL LIFT PUMP RELAY CONTROL CIRCUIT SHORT CIRCUIT.........131
P0641-SENSOR REFERENCE VOLTAGE A CKT VOLTAGE TOO HIGH..........133
P0651-SENSOR REFERENCE VOLTAGE B CKT VOLTAGE TOO HIGH..........133
P0641-SENSOR REFERENCE VOLTAGE A CKT VOLTAGE TOO LOW..........136
P0651-SENSOR REFERENCE VOLTAGE B CKT VOLTAGE TOO LOW..........136
P0645-A/C CLUTCH RELAY CIRCUIT OPEN CIRCUIT........................139
P0645-A/C CLUTCH RELAY CIRCUIT SHORT CIRCUIT......................142
P0685-ECM/PCM RELAY CONTROL CIRCUIT SHUTS OFF TOO EARLY........145
P0685-ECM/PCM RELAY CONTROL CIRCUIT SHUTS OFF TOO LATE..........147
P0703-BRAKE SWITCH SIGNAL CIRCUITS PLAUSIBILITY WITH
REDUNDANT CONTACT................................................149
iii

A/C PRESSURE SENSOR CIRCUIT SIGNAL
VOLTAGE TOO HIGH
A/C PRESSURE SENSOR CIRCUIT SIGNAL
VOLTAGE TOO LOW
A/C PRESSURE SENSOR CIRCUIT SUPPLY
VOLTAGE TOO HIGH OR LOW
A/C PRESSURE SENSOR CIRCUIT PLAUSI-
BILITY
SYSTEM VOLTAGE TOO HIGH
SYSTEM VOLTAGE TOO LOW
S/C SWITCH SIGNAL CIRCUIT SIGNAL VOLT-
AGE TOO HIGH
S/C SWITCH SIGNAL CIRCUIT SIGNAL VOLT-
AGE TOO LOW
S/C SWITCH SIGNAL CIRCUIT PLAUSIBILITY
ECM ERROR RECOVERY HAS OCCURRED
ECM ERROR REDUNDANT OVERRUN MONI-
TORING
ECM ERROR GATE ARRAY - QUANTITY STOP
ECM ERROR GATE ARRAY - COMMUNICA-
TION
ECM ERROR - COMMUNICATION NOT VERI-
FIED
STARTER RELAY CIRCUIT OPEN CIRCUIT
STARTER RELAY CIRCUIT SHORT CIRCUIT
GENERATOR FIELD CONTROL MALF BAT-
TERY VOLTAGE TOO HIGH
GENERATOR FIELD CONTROL MALF BAT-
TERY VOLTAGE TOO LOW
GENERATOR FIELD CONTROL MALF OPEN
CIRCUIT
GENERATOR FIELD CONTROL MALF SHORT
CIRCUIT
GENERATOR FIELD CONTROL MALF
CHARGING VOLTS TOO LOW
GENERATOR FIELD CONTROL MALF BAT-
TERY VOLTAGE DEVIATION TOO HIGH
GENERATOR FIELD CONTROL MALF BAT-
TERY VOLTAGE DEVIATION TOO LOW
GENERATOR FIELD CONTROL MALF UN-
STABLE CURRENT
SENSOR REFERENCE VOLTAGE A CKT VOLT-
AGE TOO HIGH
SENSOR REFERENCE VOLTAGE A CKT VOLT-
AGE TOO LOW
SENSOR REFERENCE VOLTAGE B CKT
VOLTAGE TOO HIGH
SENSOR REFERENCE VOLTAGE B CKT
VOLTAGE TOO LOW
A/C CLUTCH RELAY CIRCUIT OPEN CIRCUIT
A/C CLUTCH RELAY CIRCUIT SHORT CIR-
CUIT
ECM/PCM RELAY CONTROL CIRCUIT SHUTS
OFF TOO EARLY
ECM/PCM RELAY CONTROL CIRCUIT SHUTS
OFF TOO LATE
BRAKE SWITCH SIGNAL CIRCUITS INCOR-
RECT CAN MESSAGEBRAKE SWITCH SIGNAL CIRCUITS PLAUSI-
BILITY WITH REDUNDANT CONTACT
BRAKE SWITCH SIGNAL CIRCUITS PLAUSI-
BILITY WITH REDUNDANT CONTACT AFTER
INITIALIZATION
CLUTCH UPSTOP SWITCH PERF PLAUSIBIL-
ITY
CLUTCH UPSTOP SWITCH PERF PLAUSIBIL-
ITY WITH P/N SWITCH
FUEL RAIL PRESSURE MALFUNCTION
PRESSURE TOO HIGH - LIMITATION
FUEL RAIL PRESSURE MALFUNCTION
PRESSURE TOO LOW
FUEL RAIL PRESSURE MALFUNCTION SO-
LENOID OPEN
FUEL RAIL PRESSURE MALFUNCTION
LEAKAGE DETECTED
FUEL PRESSURE SOLENOID OPEN CIRCUIT
FUEL PRESSURE SOLENOID SHORT CIR-
CUIT
FUEL PRESSURE SOLENOID PLAUSIBILITY
IN AFTER-RUN
CALCULATED INJECTOR VOLTAGE - VOLT-
AGE 1 TOO LOW
CALCULATED INJECTOR VOLTAGE - VOLT-
AGE 2 TOO LOW
BATTERY SENSE LINE 1 VOLTAGE TOO
HIGH
BATTERY SENSE LINE 1 VOLTAGE TOO LOW
FUEL PRESS REG CURRENT CONTROL SIG-
NAL TOO HIGH
FUEL PRESS REG CURRENT CONTROL SIG-
NAL TOO LOW
GENERATOR FIELD CURRENT TOO HIGH
GENERATOR FIELD CURRENT TOO LOW
CAPACITOR VOLTAGE 1 VOLTAGE TOO HIGH
CAPACITOR VOLTAGE 1 VOLTAGE TOO LOW
CAPACITOR VOLTAGE 2 VOLTAGE TOO HIGH
CAPACITOR VOLTAGE 2 VOLTAGE TOO LOW
IGNITION SWITCH PLAUSIBILITY
AFTER RUN SHUT OFF ERROR - ZERO
QUANTITY
AFTERRUN SHUT OFF ERROR - INJ. POWER-
STAGE
VOLTAGE REGULATOR SIGNAL VOLTAGE
TOO HIGH
VOLTAGE REGULATOR SIGNAL VOLTAGE
TOO LOW
MIL/DIAG LAMP VIA J1850 BUS IN FRAME
RESPONSE ERROR
MIL/DIAG LAMP VIA J1850 BUS - STATUS
ERROR
J1850 COMMUNICATION BUS SHORT TO
VOLTAGE
J1850 COMMUNICATION BUS SHORT TO
GROUND
J1850 COMMUNICATION BUS TRANSMIT
BUFFER OVERRUN
5
GENERAL INFORMATION

Symptom:
P0560-SYSTEM VOLTAGE TOO HIGH
When Monitored and Set Condition:
P0560-SYSTEM VOLTAGE TOO HIGH
When Monitored: With the engine running.
Set Condition: The ECM detects battery voltage is above 17.5 volts.
POSSIBLE CAUSES
INTERMITTENT CONDITION
ECM - TARGET CHARGING VOLTAGE TOO LOW
GENERATOR FIELD DRIVER CIRCUIT SHORTED TO GROUND
GROUND CIRCUIT HIGH RESISTANCE
BATTERY SUPPLY CIRCUIT HIGH RESISTANCE
GENERATOR INTERNALLY SHORTED TO GROUND
ECM - FIELD DRIVER SHORTED TO GROUND
TEST ACTION APPLICABILITY
1NOTE: The battery must be fully charged and the generator belt must be in
good condition and tensioned properly before continuing.
Turn the ignition on.
With the DRB, actuate the Generator Field.
Measure the voltage between ground and the Generator Field Driver circuit by back
probing the Generator Field harness connector with a voltmeter.
Does the voltage cycle from B+ to below 2.0 volts?All
Ye s®Go To 2
No®Go To 6
NOTE: With the DRB, stop the Generator Field actuation.
2 Start the engine.
With the DRB, read the Target Charging voltage.
Is the Target Charging voltage above 13.0 volts?All
Ye s®Go To 3
No®Replace and program the Engine Control Module in accordance
with the Service Information.
Perform CHARGING VERIFICATION - VER-3.
11 7
DRIVEABILITY - DIESEL