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Symptom:
RELAY OUTPUT VOLTAGE
When Monitored and Set Condition:
RELAY OUTPUT VOLTAGE
When Monitored: Ignition On - Continuously.
Set Condition: When the CAB supply voltage is under 9.4, under 8.8 during an ABS event
or over 17.4 with vehicle speeds above 6 kph (4 mph).
POSSIBLE CAUSES
INTERMITTENT RELAY OUTPUT VOLTAGE DTC
BATTERY/CHARGING SYSTEM FAILURE
DAMAGED CAB/CAB HARNESS CONNECTOR
FUSED OPTIONAL EQUIPMENT RELAY OUTPUT CIRCUIT OPEN
FUSED B(+) CIRCUIT OPEN
GROUND CIRCUIT OPEN
ANTI-LOCK BRAKE CONTROLLER
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, read DTCs.
With the DRBIIIt, erase DTCs.
Turn the ignition off.
Turn the ignition on.
Start the engine.
Drive the vehicle above 6 km/h (4 mph) for at least 30 seconds.
Stop the vehicle.
With the DRBIIIt, read DTCs.
Does the DRBIIItdisplay RELAY OUTPUT VOLTAGE?All
Ye s!Go To 2
No!Go To 8
2 Turn the ignition off.
Perform a battery and charging system test in accordance with the Service Informa-
tion.
NOTE: Refer to symptom list for any problems related to the battery or
charging system.
Were any problems found?All
Ye s!Repair any charging system or battery related symptom(s) in
accordance with the Service Information.
Perform ABS VERIFICATION TEST - VER 1.
No!Go To 3
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BRAKES (CAB)
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TEST ACTION APPLICABILITY
3 Turn the ignition off.
Disconnect the CAB harness connector.
Inspect the CAB/CAB harness connector for damage.
Is there any broken, bent, pushed out, corroded or spread terminals?All
Ye s!Repair as necessary.
Perform ABS VERIFICATION TEST - VER 1.
No!Go To 4
4 Turn the ignition off.
Turn the ignition on.
With the DRBIIItin Sensors, read the Relay Output voltage.
Start the engine.
With the DRBIIItin Sensors, read the Relay Output voltage.
Select the Relay Output voltage that was displayed on the DRBIIIt.All
Voltage below 9.4 volts.
Go To 5
Voltage above 17.4 volts.
Go To 7
Voltage between 9.4 and 17.4 volts.
Go To 8
5 Turn the ignition off.
Disconnect the CAB harness connector.
Start the engine.
Allow the engine to idle.
WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
Measure the voltage of the Fused Optional Equipment Relay Output circuit in the
CAB harness connector.
Raise the engine speed above 2,000 RPM's.
Measure the voltage of the Fused Optional Equipment Relay Output circuit in the
CAB harness connector.
Is the voltage less than 9.4 volts?All
Ye s!Repair the Fused Optional Equipment Relay Output circuit for an
open.
Perform ABS VERIFICATION TEST - VER 1.
No!Go To 6
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BRAKES (CAB)
RELAY OUTPUT VOLTAGE ÐContinued
Page 383 of 2305

TEST ACTION APPLICABILITY
6 Turn the ignition off.
Disconnect the CAB harness connector.
Start the engine.
Allow the engine to idle.
WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
Measure the voltage of both Fused B(+) circuits in the CAB harness connector.
Raise the engine speed above 2,000 RPM's.
Measure the voltage of both Fused B(+) circuits in the CAB harness connector.
Is the voltage below 9.4 volts?All
Ye s!Repair the Fused B(+) circuit for an open.
Perform ABS VERIFICATION TEST - VER 1.
No!Go To 7
7 Turn the ignition off.
Disconnect the CAB harness connector.
Measure the voltage between the Fused B(+) circuit and both Ground circuits in the
CAB harness connector.
Is the voltage above 9.4 volts?All
Ye s!Repair any charging system related DTCs before continuing. If no
charging system or system voltage DTCs are present in any
module, replace the Controller Antilock Brake in accordance with
the Service Information.
Perform ABS VERIFICATION TEST - VER 1.
No!Repair the Ground circuit for an open.
Perform ABS VERIFICATION TEST - VER 1.
8 Turn the ignition off.
Visually inspect the related wiring harness.
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out, or corroded terminals.
Ensure the battery is fully charged.
Inspect the vehicle for aftermarket accessories that may exceed the Generator
System output.
Were any problems found?All
Ye s!Repair as necessary.
Perform ABS VERIFICATION TEST - VER 1.
No!Test Complete.
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BRAKES (CAB)
RELAY OUTPUT VOLTAGE ÐContinued
Page 384 of 2305
Symptom:
SOLENOID RELAY
When Monitored and Set Condition:
SOLENOID RELAY
When Monitored: Ignition On - Continuously.
Set Condition: When there is a voltage deviation from the expected result of a CAB
internal self check.
POSSIBLE CAUSES
INTERMITTENT SOLENOID RELAY DTC
DAMAGED CAB/CAB HARNESS CONNECTOR
FUSED OPTIONAL EQUIPMENT RELAY OUTPUT CIRCUIT OPEN
FUSED B(+) CIRCUIT OPEN
GROUND CIRCUIT OPEN
ANTI-LOCK BRAKE CONTROLLER
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, read DTCs.
With the DRBIIIt, erase DTCs.
Turn the ignition off.
Turn the ignition on.
With the DRBIIIt, read DTCs.
Does the DRBIIItdisplay SOLENOID RELAY?All
Ye s!Go To 2
No!Go To 6
2 Turn the ignition off.
Disconnect the CAB harness connector.
Inspect the CAB/CAB harness connector for damage.
Is there any broken, bent, pushed out, corroded or spread terminals?All
Ye s!Repair as necessary.
Perform ABS VERIFICATION TEST - VER 1.
No!Go To 3
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TEST ACTION APPLICABILITY
3 Turn the ignition off.
Disconnect the CAB harness connector.
Turn the ignition on.
Using a 12-volt test light connected to ground, check the Fused Optional Equipment
Relay Output circuit at the CAB harness connector.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Go To 4
No!Repair the Fused Optional Equipment Relay Output circuit for an
open.
Perform ABS VERIFICATION TEST - VER 1.
4 Turn the ignition off.
Disconnect the CAB harness connector.
Using a 12-volt test light connected to ground, check both Fused B(+) circuits at the
CAB harness connector.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Go To 5
No!Repair the Fused B(+) circuit for an open.
Perform ABS VERIFICATION TEST - VER 1.
5 Turn the ignition off.
Disconnect the CAB harness connector.
Using a 12-volt test light connected to 12-volts, check the CAB harness connector
Ground circuits.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Replace the Controller Antilock Brake in accordance with the
Service Information.
Perform ABS VERIFICATION TEST - VER 1.
No!Repair the Ground circuit for an open.
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.
Look for broken, bent, pushed out, or corroded terminals.
Were any problems found?All
Ye s!Repair as necessary.
Perform ABS VERIFICATION TEST - VER 1.
No!Test Complete.
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BRAKES (CAB)
SOLENOID RELAY ÐContinued
Page 398 of 2305

Symptom:
SYSTEM UNDERVOLTAGE
POSSIBLE CAUSES
INTERMITTENT DTC
DAMAGED CAB/CAB HARNESS CONNECTOR
FUSED OPTIONAL EQUIPMENT RELAY OUTPUT CIRCUIT HIGH RESISTANCE
FUSED B(+) CIRCUIT HIGH RESISTANCE
GROUND CIRCUIT HIGH RESISTANCE
ANTI-LOCK BRAKE CONTROLLER
TEST ACTION APPLICABILITY
1NOTE: An undercharged battery may cause this DTC to set. Repair any
Powertrain charging system DTCs before continuing.
Turn the ignition on.
With the DRBIIIt, read DTCs.
With the DRBIIIt, erase DTCs.
Turn the ignition off.
Turn the ignition on.
Start the engine.
With the DRBIIIt, read DTCs.
Does this DTC reset?All
Ye s!Go To 2
No!Go To 6
2 Turn the ignition off.
Disconnect the CAB harness connector.
Inspect the CAB/CAB harness connector for damage.
Is there any broken, bent, pushed out, corroded or spread terminals?All
Ye s!Repair as necessary.
Perform ABS VERIFICATION TEST - VER 1.
No!Go To 3
3 Turn the ignition off.
Disconnect the CAB harness connector.
Turn the ignition on.
Using a 12-volt test light connected to ground, check the Fused Optional Equipment
Relay Output circuit at the CAB harness connector.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Go To 4
No!Repair the Fused Optional Equipment Relay Output circuit for
high resistance.
Perform ABS VERIFICATION TEST - VER 1.
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BRAKES (CAB)
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TEST ACTION APPLICABILITY
4 Turn the ignition off.
Disconnect the CAB harness connector.
Using a 12-volt test light connected to ground, check both Fused B(+) circuits at the
CAB harness connector.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Go To 5
No!Repair the Fused B(+) circuit for high resistance.
Perform ABS VERIFICATION TEST - VER 1.
5 Turn the ignition off.
Disconnect the CAB harness connector.
Using a 12-volt test light connected to 12-volts, check the CAB harness connector
Ground circuits.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Replace the Controller Antilock Brake in accordance with the
Service Information.
Perform ABS VERIFICATION TEST - VER 1.
No!Repair the Ground circuit for high resistance.
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.
Look for broken, bent, pushed out, or corroded terminals.
Were any problems found?All
Ye s!Repair as necessary.
Perform ABS VERIFICATION TEST - VER 1.
No!Test Complete.
78
BRAKES (CAB)
SYSTEM UNDERVOLTAGE ÐContinued
Page 404 of 2305
9.0 CONNECTOR PINOUTS
BRAKE FLUID LEVEL SWITCHCAV CIRCUIT FUNCTION
1 20BR/YL BRAKE FLUID LEVEL INDICATOR SIGNAL
2 16BR GROUND
BRAKE LAMP SWITCH C1 (EXCEPT ESP)CAV CIRCUIT FUNCTION
1 20WT BRAKE SWITCH OUTPUT
2 16RD/BK FUSED IGNITION SWITCH OUTPUT (RUN-START)
3 20BK/BL/RD BRAKE LAMP SWITCH
4- -
BRAKE LAMP SWITCH C2 (EXCEPT ESP) - BLACKCAV CIRCUIT FUNCTION
1 16BK/BL/WT FUSED IGNITION SWITCH OUTPUT (RUN-START)
2 16BK/RD BRAKE LAMP SWITCH OUTPUT
3- -
C
O
N
N
E
C
T
O
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P
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N
O
U
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S
83
CONNECTOR PINOUTS