DTC P1600: Serial Communication Problem Between ECM & TCM: Condition
WARNING: This page is about a different car, the 2002 Suzuki Esteem. However, it is still accessible from the selected car via links, so may be relevant.
DTC is set when ECM detects no input voltage from TCM, or ECM detects a check sum error while engine is running. Possible causes are:
- Open or short circuit between TCM and ECM.
- Open TCM power or ground circuit.
- TCM malfunction.
- ECM malfunction.