Test No. 5: Key Confinement Prevention Function Does Not Operate

NOTE: Key confinement prevention function prevents the doors from being locked if ignition key is in the ignition lock cylinder.

Check key unlock warning switch. See KEY UNLOCK WARNING SWITCH under COMPONENT TESTS. If key unlock warning switch is okay, go to next step. If key unlock warning switch is defective, replace key unlock warning switch and recheck operation of key confinement prevention function. See KEY UNLOCK WARNING SWITCH under REMOVAL & INSTALLATION.
Check wiring harness and electrical connectors between key unlock warning switch and body Electronic Control Unit (ECU). See WIRING DIAGRAMS in POWER DOOR LOCKS & REMOTE KEYLESS ENTRY SYSTEMS - PRIUS article. Key unlock warning switch may also be referred to as unlock warning switch. Body ECU is located at driver's side of instrument panel on the fuse/relay box and contains an 18-pin and 20-pin electrical connector. See Figure. If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary and recheck operation of key confinement prevention function.
Check body ECU for proper voltage and input signals. See BODY ELECTRONIC CONTROL UNIT under PIN VOLTAGE TESTS. If proper voltage and input signals exist, go to next step. If proper voltage and input signals do not exist, repair as necessary and recheck operation of key confinement prevention function.
Replace body ECU with a known-good body ECU and recheck operation of key confinement prevention function. If key confinement prevention function operates properly, original body ECU was defective. If key confinement prevention function still does not operate properly, check wiring harness and electrical connectors between body ECU and key unlock warning switch for intermittent problem. See WIRING DIAGRAMS in POWER DOOR LOCKS & REMOTE KEYLESS ENTRY SYSTEMS - PRIUS article. Repair wiring harness or electrical connector as necessary.