Eclipse Vehicle P1600 Fault: Serial Communication Failure Leading to Transmission Limp Mode

Model: Mit Eclipse Fault Code: P1600 Posted: 2007-02-03 13:21

My Eclipse is displaying fault code P1600 — Serial Communication Link Failure between the ECM and TCU. As a result, the transmission remains stuck in third gear in limp mode. I have already removed both the Engine Control Module (ECM) and Transmission Control Unit (TCU) for inspection, and neither shows visible damage, burn marks, or fluid leaks. What should I check next or replace to resolve this issue? Any guidance would be greatly appreciated. Thanks, RK