Fault Cause
Connector terminal deformation.
Fault Symptoms
A 2009 Honda Accord (model code CP1) with a mileage of 120,000 km was brought in for rear-end collision repairs. After repairs, it was noticed that the parking lights could be operated even when the ignition switch was off. Additionally, when the engine was started, the parking lights remained illuminated even if their switch was off, only turning off after the engine was stopped.
Inspection and Analysis
Upon careful observation, it was found that when the ignition switch was in the ACC or ON position, the left front parking light, both rear parking lights, and the license plate light remained lit, but the right front parking light did not. The right front parking light illuminated only when the parking light switch was in the ON position.
Referencing the wiring diagram, it was determined that the parking lights were controlled by the left and right multiplex integrated control units (MICU). Since the right front parking light did not work during the fault, issues like a short circuit in the navigation wiring or a malfunction of the right MICU were ruled out, as both the navigation panel lights and the right front parking light are controlled by the same unit.
The wiring was inspected starting with the trunk, where no abnormalities were found, eliminating the possibility of accident-induced damage. Next, the wiring from the left MICU’s D11 and F10 terminals was measured. With the ignition switch in the ON position, both terminals had a 12V output, and the parking lights were illuminated. Disconnecting D11 and F10 from the MICU caused the 12V output to disappear, and all parking lights turned off.
Upon further analysis, it was confirmed that the internal wiring of the left MICU was faulty. After disassembling the left MICU, it was discovered that the connector’s 10th pin was deformed, causing contact with the ACC power supply. Additionally, the 11th pin made contact with the D11 and F10 terminals.
Fault Resolution
The deformed connector terminal was repaired. A test drive confirmed the issue was resolved.
