Function Test

NOTE:

Before testing, check the No. 14 (40 A) and No. 2 (30 A) fuses in the under-hood fuse/relay box and the No. 30 (7.5 A) fuse in the driver's under-dash fuse/relay box.
Before testing, troubleshoot the B-CAN System Diagnosis Test Mode A (see TROUBLESHOOTING - B-CAN SYSTEM DIAGNOSIS TEST MODE A ).
Aftermarket window tinting should be removed before testing.
With the defogger ON, holding a cup of hot water to the rear window will form steam that can assist in diagnosing a broken or under-performing grid line or section.
Be careful not to scratch or damage the defogger wires with the tester probe.

Turn the ignition switch to ON (II) and then turn the rear window defogger switch ON.
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 (see POWER RELAY TEST ).
  - Faulty climate control unit.
  - Faulty glass antenna coil.
  - An open in the BLU wire to the positive terminal.
- If there is voltage, go to step 3.
Fig 1: Measuring Voltage Between Positive Terminal And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Measure the voltage between negative terminal (B) and body ground. There should be less than 0.2 V.
- If there is less than 0.2 V, go to step 4.
- If there is more than 0.2 V, check for:
- An open or high resistance in the wire.
- Poor ground (G851).
Touch the voltmeter positive probe to each point on each defogger wire, and the negative probe to the negative terminal.

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.