What Causes the Hill Descent Control Malfunction Light to Illuminate?
2 Answers
Here are the relevant reasons for the malfunction light illumination: 1. Node Fault: There is a fault in the PT-CAN related lines or a certain node. Using a fault detector, it was found that the Electronic Parking Brake control module (EPB) stored one current fault code: "U111281-ESP-CAN signal failure"; the Electronic Stability Program control module (ESP) also stored one current fault code: "U100104-CAN passive error"; the Engine Control Module (ECM) stored two historical fault codes: "U01018-Lost communication with TCU" and "U012687-Lost communication with SAS"; no fault codes were stored in other modules. Analyzing the fault codes, it is inferred that there is a fault in the PT-CAN related lines or a certain node. 2. Gateway Internal Fault: A loose connection in the gateway's internal circuit causes low network voltage. Measuring the battery voltage, the voltage when the ignition switch is off is 12.6V, the voltage when starting the engine is 10.9V, and the charging voltage is 14.3V, indicating the battery is normal. Based on repair experience, it was decided to first check the network voltage of the SAS (Safety Airbag System module). Disconnecting the SAS wiring connector, the voltage on terminal 2 (CAN-H) was measured at 2.73V, and the voltage on terminal 3 (CAN-L) was 2.31V, which is normal.
As a seasoned driver with years of experience, I've encountered the hill descent control malfunction light coming on several times. This system normally helps you descend steep slopes slowly, and when the light comes on, it indicates a problem with the system. Possible causes include dirty or damaged sensors, such as the wheel speed sensor or slope sensor. Loose or short-circuited wiring connections are also common, especially after driving on wet or bumpy roads. Additionally, software errors in the control module or low battery voltage can affect the system. I recommend first checking it yourself: wipe the sensor areas with a cloth and check if any fuses are blown. If the light remains on, you must take it to a professional repair shop immediately. Otherwise, there's a high risk of losing control when descending steep slopes—safety first. Don't delay too long; fixing it promptly can save you a lot of trouble.
