Diagnostic Procedure
WARNING: This page is about a different car, the 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
For circuit wiring diagram, see Fig 1.
- Inspect the SEAT HTR fuse. Remove the SEAT HTR fuse from the driver side junction block. Check that the continuity exists of the SEAT HTR fuse. If the continuity is OK, go to the next step. If the continuity is not good, replace the fuse.
- Check the harness and connector between the battery and heater control housing. See Fig 2. If the voltage is OK, go to the next step. If the voltage is not good, repair or replace the harness or connector.
- Inspect the seat heater. See Fig 3. If the results are OK, go to the next step. If the results are not good, replace the seat heater. See SEAT HEATER (SEAT CUSHION) and/or SEAT HEATER (SEAT BACK) under REMOVAL & INSTALLATION.
- Check the harness and connector between the seat heater and body ground. If the harness and connector is OK, go to the next step. If the harness and connector is not good, repair or replace the harness or connector.
- Inspect the heater control housing sub-assembly. See Fig 4. If the results are OK, repair or replace the harness or connector. If the results are not good, check and replace the heater control housing sub-assembly. See AUTOMATIC A/C-HEATER SYSTEMS article in HVAC.