Diagnosing Fault Code 113.298.02 on the CAT D6R: Brake Pedal Switch Troubles and Field Solutions

[MikePhua]

Introduction: When a Fault Code Disrupts a Workhorse
The Caterpillar D6R dozer is a staple in earthmoving fleets, known for its durability and mechanical simplicity. But even the most reliable machines can throw a wrench into operations when fault codes appear unexpectedly. One such code—113.298.02—relates to the service brake pedal switch and can trigger intermittent or erratic behavior in the transmission control system. This article breaks down the meaning of the code, explains the underlying systems, and offers practical steps for diagnosis and repair.
Understanding the Fault Code Structure
Caterpillar fault codes follow a structured format:
- MID 113: Refers to the transmission control module
- CID 298: Identifies the brake pedal switch circuit
- FMI 02: Indicates an erratic, intermittent, or incorrect signal
In plain terms, fault code 113.298.02 means the transmission controller is receiving unreliable data from the brake pedal switch—often due to misalignment, wear, or electrical issues.
Terminology Clarification
- Service Brake Pedal Switch: A sensor that detects when the brake pedal is fully depressed. It signals the controller to engage the parking brake or interrupt transmission functions.
- PWM (Pulse Width Modulation): A method of controlling voltage by varying the duty cycle of a signal. Used in some brake systems for fine control.
- Component Data Display Mode: A diagnostic mode that shows live data from machine sensors and switches.
- CONN 19: A specific connector in the wiring harness associated with the brake pedal switch.
How the Brake Pedal Switch Works
On the D6R, the brake pedal switch plays a critical role in safety and control:

• When the pedal is pressed to the floor, the switch closes its contacts
  
• This sends a signal to the transmission controller to engage the parking brake
  
• It also disables forward/reverse travel to prevent unintended movement
  
• If the switch is misaligned or faulty, the controller may receive false signals, triggering fault codes or erratic behavior
  

Field Anecdote: The Flash That Warned the Technician
A technician in Saskatchewan was troubleshooting a D6R with this fault code. While probing the switch terminals with the master switch ON, he accidentally shorted a live wire with his screwdriver—resulting in a bright flash and a scorched terminal. The lesson? Always disconnect power or isolate the circuit before testing. The switch carries 24 volts and can arc if mishandled.
Diagnostic Steps and Testing Procedure
To confirm the issue and resolve the fault:
1. Access the switch behind the cover above the brake pedal
2. Unplug connector CONN 19 (wires: 198-RD and G731-GY)
3. Use a multimeter to test continuity across the switch terminals
4. The switch should be open (no continuity) until the pedal is nearly at the floor
5. When fully depressed, the contacts should close, showing continuity
6. If the switch behaves erratically, replace or adjust it
7. Check wire terminals for corrosion, loose screws, or damaged insulation
Adjustment Tips

• Loosen the mounting screws and reposition the switch to ensure it activates only at full pedal depression
  
• Use a feeler gauge to set consistent clearance between the pedal and switch actuator
  
• Confirm that the switch does not trigger prematurely, which can confuse the controller
  

Electrical Safety and Precautions

• Always turn off the master switch before working on live circuits
  
• Use insulated tools when probing connectors
  
• Label wires before disconnecting to avoid miswiring
  
• Avoid testing PWM circuits with basic multimeters—use compatible diagnostic tools
  

Component Compatibility and Voltage Notes

• The brake pedal switch operates on 24 volts, unlike some PWM-controlled components that use 5 volts
  
• The hand-operated park button shares the same voltage circuit
  
• Mixing up these systems can lead to misdiagnosis or component damage
  

Preventive Maintenance Recommendations

• Inspect the brake pedal switch quarterly for wear or misalignment
  
• Clean connectors with contact cleaner and apply dielectric grease
  
• Check pedal travel and linkage for binding or excessive play
  
• Log fault codes and resolution steps for future reference
  
• Train operators to report erratic brake behavior immediately
  

Conclusion: A Small Switch with Big Consequences
The CAT D6R’s fault code 113.298.02 may point to a simple switch, but its implications for safety and control are significant. By understanding the electrical and mechanical interplay behind the brake pedal switch, technicians can resolve the issue confidently and prevent future disruptions. In the world of heavy equipment, even the smallest component can make or break a day’s work—and knowing how to tame a fault code is part of keeping the iron moving.