Possible causes – Weak battery– Faulty Transmission Control Module (TCM)– Harness is open or shorted between (TCM) and Engine Control Module (ECM)– Poor circuit electrical connection between (TCM) and (ECM) Tech description There is a service bulletin for the 2001 Infiniti I30. 2001 Infiniti I30 Factory Service Bulletin OBDII Code P1605 When is the obd…