Dodge Ram Truck 1500-2500-3500. Manual — part 145

BRAKE SWITCH CIRCUIT — 81 (CONTINUED)

2.

BRAKE LAMP SWITCH

Turn ignition off.

Disconnect the Brake Lamp Switch harness connector.

Turn ignition on.

With the scan tool, monitor the brake switch status.

Connect and disconnect a jumper wire between the Ground circuit and the Brake Switch Signal circuit.

Does the scan tool display correctly with the jumper wire connected and disconnected?

Yes

>> Replace the Brake Lamp Switch in accordance with the Service Information.

Perform ABS VERIFICATION TEST - VER 1. (Refer to 5 - BRAKES/ELECTRICAL - DIAGNOSIS AND
TESTING)

No

>> Go To 3

3.

BRAKE SWITCH SIGNAL CIRCUIT SHORT TO VOLTAGE

Turn the ignition off.

Disconnect the CAB Module harness connector.

Turn the ignition on.

Measure the voltage of the Brake Switch Signal circuit.

Is there any voltage present?

Yes

>> Repair the Brake Switch Signal circuit for a short to volt-

age.

Perform ABS VERIFICATION TEST - VER 1. (Refer to 5 -
BRAKES/ELECTRICAL - DIAGNOSIS AND TESTING)

No

>> Go To 4

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BRAKES - ABS - ELECTRICAL DIAGNOSTICS

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BRAKE SWITCH CIRCUIT — 81 (CONTINUED)

4.

BRAKE SWITCH SIGNAL CIRCUIT OPEN

Turn the ignition off.

Measure the resistance of the Brake Switch Signal circuit between the
CAB harness connector and the brake switch harness connector.

Is the resistance above 5.0 ohms?

Yes

>> Repair the open Brake Switch Signal circuit.

Perform ABS VERIFICATION TEST - VER 1. (Refer to 5 -
BRAKES/ELECTRICAL - DIAGNOSIS AND TESTING)

No

>> Go To 5

5.

GROUND CIRCUIT OPEN

Using a 12–volt test light connected to 12 volts, check the Ground cir-
cuit at the brake switch harness connector.

NOTE: The test light should be illuminated and bright. Compare
the brightness to that of a direct connection to the battery.

Is the test light illuminated and bright?

Yes

>> Replace the Controller Anti-lock in accordance with the

Service Information. Refer to the symptom *Replacing the
Controller Anti-lock Brake for additional information.

Perform ABS VERIFICATION TEST - VER 1. (Refer to 5 -
BRAKES/ELECTRICAL - DIAGNOSIS AND TESTING)

No

>> Repair the Ground circuit for an open circuit or high resis-

tance.

Perform ABS VERIFICATION TEST - VER 1. (Refer to 5 -
BRAKES/ELECTRICAL - DIAGNOSIS AND TESTING)

DR/DH

BRAKES - ABS - ELECTRICAL DIAGNOSTICS

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ECU INTERNAL FAILURE -75

For a complete wiring diagram Refer to Section 8W.

•

When Monitored:
Ignition on.

•

Set Condition:
When the CAB internal micro processor has an open/short in the status line which fails to transmit at the
correct frequency.

Possible Causes

WHEEL SPEED SENSOR FAILURE

CONTROLLER ANTI-LOCK BRAKE

Diagnostic Test

1.

VERIFYING DTC

NOTE: Before continuing, check the Controller Anti-lock Brake harness connector terminals for corrosion,
damage, or terminal push out. Repair as necessary.
Turn the ignition on.

With the DRBIII

T

, erase DTC’s.

Turn the ignition off.

Turn the ignition on.

NOTE: Ensure that the Wheel Speed sensor are working properly.
With the DRBIII

T

, read DTC’s.

Does the DRBIII

T

display ECU INTERNAL FAILURE and a WHEEL SPEED SENSOR DTC’S?

Yes

>> Refer to the symptom list and diagnose the display Wheel Speed DTC.

Perform ABS VERIFICATION TEST - VER 1. (Refer to 5 - BRAKES/ELECTRICAL - DIAGNOSIS AND
TESTING)

No

>> Replace the Controller Anti-lock Brake in accordance with the Service Information. Refer to the symptom

*Replacing the Controller Anti-Lock Brake for additional information.

Perform ABS VERIFICATION TEST - VER 1. (Refer to 5 - BRAKES/ELECTRICAL - DIAGNOSIS AND
TESTING)

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BRAKES - ABS - ELECTRICAL DIAGNOSTICS

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EXCESSIVE DUMP TIME — 69

For a complete wiring diagram Refer to Section 8W.

•

When Monitored:
Ignition on.

•

Set Condition:
Antilock mode is active. Wheel speed is below 4 MPH (RWAL) and above 4 MPH (ABS). Vehicle is in two
wheel drive mode. Wheel speed history ruling out any unusual events during the proceeding 15 second
(RWAL) and 9 second (ABS). Need for more then maximum allowable dump cycles.

Possible Causes

INTERMITTENT EXCESSIVE DUMP TIME DTC

WHEEL SPEED WIRING HARNESS AND CONNECTORS

SUSPENSION

TONE WHEEL

WHEEL BEARING

BRAKE SYSTEM MECHANICAL CONDITION

ANTI-LOCK BRAKE HYDRAULIC CONTROL UNIT

Diagnostic Test

1.

BRAKE SYSTEM MECHANICAL CONDITION

Inspect the front and rear brakes for a mechanical condition that would cause any wheel(s) to lock-up during brak-
ing.

Inspect the Parking Brake to make sure it releases properly.

Were any problems found?

Yes

>> Repair the braking system as necessary in accordance with the Service Information.

Perform ABS VERIFICATION TEST - VER 1. (Refer to 5 - BRAKES/ELECTRICAL - DIAGNOSIS AND
TESTING)

No

>> Go To 2

2.

TONE WHEEL

Inspect each Tone Wheel for damage, missing teeth or looseness in accordance with the Service Information.

NOTE: The Tone Wheel Teeth should be perfectly square, not bent or nicked.

Were any problems found?

Yes

>> Replace the Tone Wheel as necessary in accordance with the Service Information.

Perform ABS VERIFICATION TEST - VER 1. (Refer to 5 - BRAKES/ELECTRICAL - DIAGNOSIS AND
TESTING)

No

>> Go To 3

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BRAKES - ABS - ELECTRICAL DIAGNOSTICS

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