Honda Accord/Civic/Prelude 1973-1983 Repair Guide

Rear Window Defogger System

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The rear window defogger system consists of a rear window with 2 vertical bus bars and a series of electrically connected grid lines baked on the inside surface. A control switch and a relay are also used in this system.

Since the grid lines can be damaged or scraped off with sharp instruments, caution should be used when cleaning the glass or removing foreign materials, decals or stickers. Normal glass cleaning solvents or hot water used with rags or toweling is recommended.

REMOVAL & INSTALLATION



Rear Window Defogger Switch
ACCORD
  1. Disconnect the negative battery cable. Remove the combination meter housing.
  2.  
  3. Pull out the combination meter housing far enough to gain access to the rear defroster switch retaining screws.
  4.  
  5. Disconnect the switch electrical connector. Remove the switch retaining screws and remove the switch from the rear of the meter housing.
  6.  
  7. Installation is the reverse order of the removal procedure. Check system for proper operation.
  8.  

CIVIC
  1. Disconnect the negative battery cable and remove the lower dashboard panel.
  2.  
  3. Disconnect the wire harness from behind the console. Depress the switch locking pawls and remove the switch from the front of the dash panel.
  4.  
  5. Installation is the reverse order of the removal procedure. Check system for proper operation.
  6.  

PRELUDE
  1. Disconnect the negative battery cable. Lower the steering column and remove the lower dashboard panel.
  2.  
  3. Remove the 4 instrument panel retaining screws. Pull the instrument panel out and disconnect the wire connectors.
  4.  
  5. Remove the instrument panel. Remove the rear defroster switch retaining screws and pull the switch out of the instrument panel.
  6.  
  7. Installation is the reverse order of the removal procedure. Check system for proper operation.
  8.  

COMPONENT TESTING



Rear Defroster Relay

See Figure 1

  1. Check for continuity between top left A terminal and the bottom left B terminal, when applying battery voltage to upper right C terminal and grounding the lower right D terminals.
  2.  



Click image to see an enlarged view

Fig. Fig. 1: Testing the defroster relay

  1. Once the voltage is removed from the C and D terminals, there should be no continuity in the relay. If the relay fails this test, replace it. The relays are located under the dash on the left side.
  2.  

Rear Window Defogger Grid

See Figure 2

  1. Turn ON the rear window defroster switch. Connect the positive lead of a voltmeter to the center of each filament and connect the negative lead to the body of the vehicle.
  2.  



Click image to see an enlarged view

Fig. Fig. 2: Defogger circuit-typical

  1. The standard voltage at the center of the filament is 6 volts. If the meter is higher than 6 volts, the problem exists in the ground side of the filament.
  2.  
  3. If the meter indication is low or 0, the problem is between the center and the power side. Isolate the problem grid line and mark the break in the grid wire.
  4.  

 
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