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System Testing

  1. Start engine. Ensure coolant temperature is below 109°F (43°C). Using a voltmeter, ensure voltage is present between positive terminal and body ground. See POSITIVE TERMINAL WIRE COLORS  table for correct wire color application. Ensure voltmeter probe is inserted from rear of connector. See Fig 1.
    POSITIVE TERMINAL WIRE COLORS

    Application Wire Colors
    Corolla FWD White/Red
    Corolla RWD White/Blue
    Pickup, 4Runner (1)
    Tercel Sedan White/Red
    Tercel Wagon White/Blue
    (1) Wire color not available.
  2. Warm engine to above 131°F (55°C). Ensure no voltage is present. If no problem is found, system is okay. If system fails to operate as specified, perform following component tests.
Fig 1: Checking Cold Mixture Heater
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