RAM 1500 Van V8-5.2L CNG VIN T (1999)
Rear Window Defogger: Testing and Inspection
Defogger System Operation Check
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, REFER TO AIR BAGS AND SEAT BELTS/AIR BAGS BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE.
FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
The operation of the electrically heated rear window defogger system can be confirmed in one of the following manners:
1. Turn the ignition switch to the On position. While monitoring the instrument panel voltmeter, set the defogger switch in the On position. When the
defogger switch is turned On, a distinct voltmeter needle deflection should be noted.
2. Turn the ignition switch to the On position. Set the defogger switch in the On position. The rear window defogger operation can be checked by
feeling the rear window glass. A distinct difference in temperature between the grid lines and the adjacent clear glass can be detected within three
to four minutes of operation.
Rear Window Glass Grid Test
3. Using a 12-volt DC voltmeter, contact the rear glass heating grid terminal A (right side) with the negative lead, and terminal B (left side) with the
positive lead. The voltmeter should read battery voltage.
The above checks will confirm system operation. Illumination of the defogger switch indicator lamp means that there is electrical current available at the
output of the rear window defogger logic and timer circuitry, but does not confirm that the electrical current is reaching the rear glass heating grid lines.
If the defogger system does not operate, the problem should be isolated in the following manner:
1. Confirm that the ignition switch is in the On position.
