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Rear Window Defogger Function Test

NOTE:
  • Before testing, check the No. 10 (7.5 A), No. 59 (20 A), and No. 60 (IGN) (50 A) fuse in the under-dash fuse/relay box.
  • Be careful not to scratch or damage the defogger wires with the tester probe.
  1. Turn the ignition switch to ON (II), then turn the rear window defogger switch ON.
  1. Measure the voltage between the positive terminal (A) and body ground. There should be battery voltage.
    • If there is no voltage, check for:
    • -
      Faulty rear window defogger relay.
      -
      Faulty rear window defogger switch.
      -
      An open in the BLU wire to the positive terminal.
    • If there is battery voltage, go to Step 3 .
  1. Turn the ignition switch to LOCK (0).
  1. Disconnect the negative terminal (B) from the rear window defogger.
  1. Check for continuity between the negative terminal and body ground. There should be continuity.
    If there is no continuity, check for an open in the BLK wire or poor ground (G602). If there is continuity, go to Step 6 .
  1. Reconnect the negative terminal to the rear window defogger.
  1. Turn the ignition switch to ON (II), then turn the rear window defogger switch ON.
  1. Touch the voltmeter positive probe to each point on each defogger wire, and the negative probe to the negative terminal.
    • If the voltage is as specified, the defogger wire up to that point is OK.
    • If the voltage is not as specified, repair the defogger wire.
    • -
      If it is more than specified at one of the points, there is a break in the negative half of the wire.
      -
      If it is less than specified at one of the points, there is a break in the positive half of the wire.