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Home >> Toyota >> 2001 >> 4Runner Base >> Repair and Diagnosis >> External Pages >> Different car >> Section 4 (Automatic A/C-Heater Systems) >> System Tests >> Back-Up Power Source Circuit
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Back-Up Power Source Circuit

WARNING: This page is about a different car, the 2001 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
  1. Remove A/C control assembly, leaving harness connectors connected. See A/C CONTROL ASSEMBLY  under REMOVAL & INSTALLATION. Turn ignition on. Measure voltage between connector A7 terminal No. 8 (Red/Green wire) and ground. If battery voltage is present, back-up power source circuit is okay. If battery voltage is not present, go to next step.
  2. Remove ECU-B (7.5-amp) fuse from instrument panel junction block. Check ECU-B fuse. Replace fuse as necessary. If fuse is okay, repair wiring between A/C-heater control assembly and battery. See WIRING DIAGRAMS .
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