Function Test

Before troubleshooting the rear window circuit, perform multiplex integrated control system troubleshooting using B-CAN System Diagnosis Test Mode A (see TROUBLESHOOTING - B-CAN SYSTEM DIAGNOSIS TEST MODE A ).

NOTE:

Be careful not to scratch or damage the defogger wires with the tester probe.
Before testing, check the No. 14 (40 A) fuse in the under-hood fuse/relay box and No. 30 (7.5 A) fuse in the under-dash fuse/relay box.

Measure the voltage between the positive terminal (A) and body ground with the ignition switch and defogger switch ON.
There should be battery voltage.
- If there is no voltage, check for:
  - Faulty defogger relay.
  - Faulty window antenna coil.
  - Faulty climate control unit (audio-HVAC-display module)
  - An open in the BLK/YEL wire to the positive terminal.
- If there is voltage, go to step 2.
  
  Fig 1: Measuring Voltage Between Positive Terminal And Body Ground With Ignition Switch And Defogger Switch
  Courtesy of AMERICAN HONDA MOTOR CO., INC.
Disconnect the negative terminal (B) from the rear window defogger.
Check for continuity between the negative terminal (B) and body ground.
If there is no continuity, check for an open in the BLK/YEL wire and ground. If there is continuity, go to step 4.
Reconnect the negative terminal to the rear window defogger.
Turn the ignition switch ON (II) and the rear window defogger switch ON.
Touch the voltmeter positive probe to the points (1), (2), (3) 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 atone 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 negative half of the wire.