Rear Window Defogger
Function Test
CAUTION: Be careful not to scratch or damage the
defogger wires with the tester probe.
1. Check for voltage between the positive terminal
and body ground with the ignition switch and the
defogger switch ON. There should be battery
voltage.
• If there is no voltage, check for:
— Faulty defogger relay.
— An open in the BLK/GRN wire.
• If there is battery voltage, go to step 2.
POSITIVE TERMINAL NEGATIVE TERMINAL
2. Disconnect the positive terminal, check for con-
tinuity between the negative terminal and body
ground. If there is no continuity, check for an open
in the defogger ground wire.
3. Reconnect the positive terminal, touch the
voltmeter positive lead to the middle of each defog-
ger wire, and the negative lead to the negative ter-
minal. There should be approximately 6 V with the
ignition switch and the defogger switch ON.
• If the voltage is as specified, the defogger wire
is OK.
• If there is battery voltage, the defogger wire is
broken on the negative side.
• If there is no voltage, the defogger wire is
broken on the positive side.
Defogger Wires Repair
To make an effective repair, the broken section must be
no longer than one inch.
1. Lightly scrub the area around the break with fine
steel wool, then clean it with alcohol.
2. Carefully mask above and below the broken section
with cellophane tape.
OPEN
CELLOPHANE
TAPE
DEFOGGER WIRE
3. Using a small brush, apply a heavy coat of silver
conductive paint extending about 1/8″ on both
sides of the break. Thoroughly mix the paint before
use. Let it dry for thirty minutes.
PAINT
4. Check for proper operation with a voltmeter (it
should read half of battery voltage at the mid-
point).
5. Apply a second coat of paint in the same way. Let it
dry for three hours before removing the tape.
Function Test
CAUTION: Be careful not to scratch or damage the
defogger wires with the tester probe.
1. Check for voltage between the positive terminal
and body ground with the ignition switch and the
defogger switch ON. There should be battery
voltage.
• If there is no voltage, check for:
— Faulty defogger relay.
— An open in the BLK/GRN wire.
• If there is battery voltage, go to step 2.
POSITIVE TERMINAL NEGATIVE TERMINAL
2. Disconnect the positive terminal, check for con-
tinuity between the negative terminal and body
ground. If there is no continuity, check for an open
in the defogger ground wire.
3. Reconnect the positive terminal, touch the
voltmeter positive lead to the middle of each defog-
ger wire, and the negative lead to the negative ter-
minal. There should be approximately 6 V with the
ignition switch and the defogger switch ON.
• If the voltage is as specified, the defogger wire
is OK.
• If there is battery voltage, the defogger wire is
broken on the negative side.
• If there is no voltage, the defogger wire is
broken on the positive side.
Defogger Wires Repair
To make an effective repair, the broken section must be
no longer than one inch.
1. Lightly scrub the area around the break with fine
steel wool, then clean it with alcohol.
2. Carefully mask above and below the broken section
with cellophane tape.
OPEN
CELLOPHANE
TAPE
DEFOGGER WIRE
3. Using a small brush, apply a heavy coat of silver
conductive paint extending about 1/8″ on both
sides of the break. Thoroughly mix the paint before
use. Let it dry for thirty minutes.
PAINT
4. Check for proper operation with a voltmeter (it
should read half of battery voltage at the mid-
point).
5. Apply a second coat of paint in the same way. Let it
dry for three hours before removing the tape.