DTC P1660: A/T FI Data Line Failure

Perform PCM reset procedure. See PCM RESET PROCEDURE/CLEARING CODES under SELF-DIAGNOSTIC SYSTEM. Turn ignition off. Start engine and allow to idle for at least one minute. If DTC P1660 resets, go to next step. If DTC P1660 does not reset, problem is intermittent. System is okay at this time. Check for poor connections or loose wires between TCM and PCM. Repair as necessary.
Turn ignition to OFF. Check for Blue wire continuity between TCM 26-pin connector terminal No. 20 and the PCM 22-pin connector terminal No. 2. Refer to the WIRING DIAGRAMS article. See Figure . If continuity exists, go to next step. If continuity does not exist, repair open Blue wire.
Disconnect PCM 22-pin connector and TCM 26-pin connector. Check for continuity between ground and PCM 22-pin connector terminal No. 2 (Blue wire). If continuity does not exist, go to next step. If continuity exists, repair short in Blue wire between PCM and TCM.
Measure voltage between TCM 26-pin connector terminals No. 12 (Black/Yellow wire) and No. 13 (Brown/Black wire), and between terminals No. 25 (Black/Yellow wire) and No. 26 (Brown/Black wire). If battery voltage is present, go to next step. If battery voltage is not present, repair open or short in suspect Black/Yellow wire between TCM and ECU fuse No. 4 (20-amp). If Black/Yellow wires are okay, repair open in suspect Brown/Black wire between TCM and G101 ground connection located on left side of engine. See WIRING DIAGRAMS article.
Substitute a known-good TCM. If DTC P1660 does not reset, replace original TCM. If DTC P1660 resets, substitute a known-good PCM, then recheck. If symptom or indication goes away, replace original PCM.