Rear Window Defogger Function Test

• Be careful not to scratch or damage the defogger wires with the tester probe.
  
• Before testing, check the No. 12 (20A) fuse in the under-dash fuse/relay box.
  

1.

Check for 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: an open in the wire between the defogger switch and positive terminal. faulty the defogger switch If there is battery voltage, go to 2.

2.	Check for continuity between the negative terminal (B) and body ground. If there is no continuity, check for: an open in the BLK wire. Poor ground (G602)

3.

Touch the voltmeter positive probe to the halfway point of each defogger wire, and the negative probe to the negative terminal. There should be about 6 V with the ignition switch and the defogger switch ON. If the voltage is as specified, the defogger wire is OK. If the voltage is not as specified, repair the defogger wire. If it is more than 6 V, there is a break in the negative half of the wire. If it is less than 6 V, there is a break in the positive half of the wire.