Test No. 51: Horns Operate Abnormally
WARNING: This page is about a different car, the 2002 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
- Turn ignition off. Separate body control ECU from driver side junction block. See BODY CONTROL ELECTRONIC CONTROL UNIT under REMOVAL & INSTALLATION. Using a DVOM, check voltage reading between 12-pin driver side junction block-to-body control ECU connector terminal No. 10 and good body ground point. See Figure. See HORN in SYSTEM WIRING DIAGRAMS article. With horn button depressed, voltage should be below 1 volt; with horn button released, voltage should be 10-14 volts. Check Black wire between battery and horn relay. See POWER DISTRIBUTION in SYSTEM WIRING DIAGRAMS article. Voltage should be 10-14 volts. If wires, harnesses and connectors are okay, go to next step. If wires, harnesses or connectors are not okay, repair as required. After repairs, perform confirmation test. See CONFIRMATION TEST .
- Check wiring harnesses and electrical connectors between battery and engine compartment junction block, between engine compartment junction block and driver side junction block, between engine compartment junction block and horns, between driver side junction block and body control ECU, and all power and ground connections. See HORN and POWER DISTRIBUTION in SYSTEM WIRING DIAGRAMS article. If wiring harnesses or electrical connectors are defective, repair as necessary. After repairs, perform confirmation test. See CONFIRMATION TEST .