Using a wiring diagram, check continuity of the high and low CAN Bus wires (usually orange/black and orange/brown) between the TCM and ECM. 4. Typical Fixes
The transmission or braking module itself is failing to communicate. p1648-vw
If internal module damage is diagnosed. If you can provide: The exact vehicle year and model (e.g., 2004 Passat 1.8T). Any other fault codes (e.g., P1626, ABS codes). If the ABS or Transmission light is on. Using a wiring diagram, check continuity of the
Improperly installed alarms, stereos, or OBD2 tuning devices interfering with data lines. 2. Symptoms Check Engine Light (MIL) illumination. Using a wiring diagram
Secondary Air Injection System Incorrect Flow Detected. P1648. 18056. Data Bus Powertrain Malfunction. Customer. JustAnswer Jeep Grand Cherokee Diesel P0700 P1648 Codes Explained