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Defogger Relay Test: LS400

WARNING: This page is about a different car, the 1992 Lexus SC 400, 1992 Lexus SC 300, 1992 Lexus LS 400, and 1992 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. Remove relay from junction block No. 1 under left side of dash. Using an ohmmeter, check for continuity between relay terminals No. 3 and 4. See Fig 1. If continuity does not exist, replace relay. If continuity exists, go to next step.
    Fig 1: Identifying Rear Defogger Relay Terminals (LS400)
    G92H01017Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. Check for continuity between terminals No. 1 and 2. If continuity exists, replace relay. If continuity does not exist, go to next step.
  3. Connect battery voltage to relay terminals No. 3 and 4. Check for continuity between terminals No. 1 and 2. If continuity exists, relay is okay. If continuity does not exist, replace relay.
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