What does code P1685 mean?

Q: What does code P1685 mean?

Driver 5 Line 5. P1685 on GM vehicles means the powertrain control module (PCM) has detected a fault on the serial data line it uses to communicate with the instrument panel cluster, specifically the circuit labeled Driver 5 Line 5 in GM's class 2 data bus architecture. The PCM monitors the voltage and message traffic on this line and sets the code when the expected signal is missing, shorted, or corrupted, which typically knocks out cluster functions like the odometer, PRNDL display, or warning lamps.

DTC codes / GM codes / P1685

P1685 · GMDriver 5 Line 5

P1685 on GM vehicles means the powertrain control module (PCM) has detected a fault on the serial data line it uses to communicate with the instrument panel cluster, specifically the circuit labeled Driver 5 Line 5 in GM's class 2 data bus architecture. The PCM monitors the voltage and message traffic on this line and sets the code when the expected signal is missing, shorted, or corrupted, which typically knocks out cluster functions like the odometer, PRNDL display, or warning lamps.

SystemPowertrain

Code typeGM specific

SeverityMedium

Fix difficultyProfessional

AreaComputer and output circuits

Guidance is general and written for GM vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.