C117498 - C117498 Motor Drive Chip Temperature Abnormality

C117498 Fault Severity Definition

C117498 represents a specific diagnostic trouble code (DTC) for monitoring motor drive chip temperature within the Electronic Parking Brake (EPB) system. In this control architecture, the Electronic Parking Controller is responsible for sending precise control commands to the motor drive chip to execute locking and releasing actions of the parking brake. The appearance of this fault code indicates that the internal hardware monitoring system of the control unit has detected that the operating temperature of the motor drive chip has exceeded the preset safety threshold. From a system logic perspective, this is a direct manifestation of the thermal protection mechanism being triggered, aimed at preventing permanent damage to the drive module or motor loss of step due to overheating. This code belongs to critical hardware health metrics in the diagnostic tree and usually implies abnormalities in the thermal management circuits inside the controller, the chip itself, or its integrated cooling system.

Common Fault Symptoms

When C117498 fault is recorded, the vehicle electronic parking system will enter a protective restricted state, specifically as follows:

• Instrument Warning Indicator: The electronic handbrake light or red brake system warning light on the driver's side dashboard stays on constantly, indicating a system fault.
• Function Execution Impaired: Unable to complete the braking clamping (lock) action via the electronic parking button on the center console; it may also manifest as inability to release the braking state after engine shutdown.
• System Enters Failure Mode: To ensure driving safety, the controller will cut motor drive output, resulting in mechanical braking remaining in the current state; the system indicates complete function failure, requiring tow rescue or power cycle reset processing.
• Stored Fault Memory: The fault code is stored in the controller's DTC memory and remains recorded after ignition cycle restart until a specific clearing procedure is completed.

Core Fault Cause Analysis

Based on original data and control principles, the root causes of this fault can be summarized into potential anomalies across the following three dimensions:

1. Hardware Components (Drive Chip & Cooling System):

   • The motor drive chip inside the Electronic Parking Controller has excessively high internal junction temperature due to long-term high-load operation.
   • The temperature sensor within the chip itself fails, outputting false high-temperature signals that trigger protection logic.
   • Heavy dust accumulation on heat sinks around the controller or blocked airflow channels prevent heat from being dissipated to the surrounding environment in a timely manner.

2. Wiring and Connectors (Physical Connection):

   • Loose, oxidized, or short-circuited signal lines connecting the motor drive chip and temperature sensor cause the temperature feedback data read by the controller to differ from the actual environment.
   • Voltage fluctuations occur at the power supply end during motor drive chip operation, causing incorrect actuation of the chip overheat protection mechanism.

3. Controller (Logic Operation):

   • Deviations in the control logic inside the Electronic Parking Control Unit prevent it from correctly comparing temperature sensor feedback values against fault thresholds.
   • Fault record bits in memory are incorrectly set, causing the system to enter a permanent lock state.

Technical Monitoring and Trigger Logic

The determination of this fault code relies on the controller's real-time closed-loop monitoring of the motor drive chip's thermal status. The specific logic flow is as follows:

• Monitoring Target: The Electronic Parking Controller continuously acquires analog signals from the temperature sensor of the motor drive chip (typically feedback as digitally quantified voltage or PWM duty cycle) and compares them with the preset maximum allowable operating temperature.
• Trigger Condition: The unique prerequisite for fault determination is that the Start Switch is in ON Gear. At this time, the controller's power management module activates, self-check programs begin running, and the system scans the initial state and real-time temperature of the motor drive chip.
• Judgment Threshold Logic: When the monitored chip temperature value continuously exceeds the safety limit ($T_{limit}$) for a duration exceeding the allowed time window ($\Delta t$), or when a non-physical jump anomaly in the temperature signal is detected, the controller will immediately judge triggering C117498 fault condition.
• Data Processing Mechanism: This monitoring process occurs only during static self-check and dynamic operation after ignition switch activation; once the above temperature anomaly conditions are met, the controller will write the fault code and activate failure protection mode until repair and reset procedures are completed.