2014 Jeep Wrangler JK Factory Service Manual 08 - Electrical

Heated Glass

DESCRIPTION

CAUTION:

Grid lines can be damaged or scraped off with sharp instruments. Care should be taken when cleaning or removing foreign materials, decals or stickers from the rear glass. Normal glass cleaning solvents or hot water used with soft toweling is recommended.


The rear window defogger system, also known as electric backlight (EBL), consists of two vertical bus bars (1) linked by a series of grid lines (2) fired onto the inside surface of the rear window (3).

The EBL system is turned on or off by a switch located in the A/C-heater control at the center of the instrument panel (Refer to 08 - Electrical/8G - Heated/Cooled Systems/Heated Glass/SWITCH, Defogger - Description) .

OPERATION



NOTE:

ATC control shown. MTC control similar.


When equipped, the Electric Back Light (EBL) system is controlled by a momentary switch located in the mode control knob (4), on the A/C-heater control (1) in the instrument panel. When the rear window defogger switch is pressed to ON with the ignition switch in RUN, the switch sends a request signal over the Controller Area Network (CAN) bus to the Totally Integrated Power Module (TIPM) to energize the internal EBL high side driver. When energized, the EBL high side driver provides battery current to the rear window defogger grid lines. An amber indicator in the control knob will illuminate to indicate when the EBL system is ON.The grid lines heat the glass to help clear the rear window surface of fog or frost.


NOTE:

The EBL system turns off automatically after 10 minutes of initial operation. Each following activation cycle of the EBL system will last 5 minutes.

The EBL system will be automatically turned off after an initial programmed time interval of about ten minutes as long as the ignition switch is in RUN. After the initial time interval has expired, if the rear window defogger switch is pressed to ON again during the same ignition cycle, the EBL system will automatically turn off after about five minutes. The EBL system will also turn off if the ignition switch is turned to any position other than RUN or by manually pressing the rear window defogger switch a second time.

Repair of the rear window defogger grid lines, bus bars, terminals or pigtail wires can be accomplished using the Mopar® Rear Window Defogger Repair Kit (Part Number 04549275) or equivalent (Refer to 08 - Electrical/8G - Heated/Cooled Systems/Heated Glass/GRID, Defogger - Standard Procedure) .

The EBL control system is diagnosed using a scan tool (Refer to 28 - DTC-Based Diagnostics).

DIAGNOSIS AND TESTING - ELECTRIC BACK LIGHT (EBL) SYSTEM



NOTE:

Illumination of the defogger switch indicator lamp does not necessarily mean that electrical current is reaching the rear window glass heating grid.


NOTE:

See Wiring Information for circuit descriptions and diagrams.

Operation of the EBL system can be confirmed by the following:



NOTE:

Typical heated rear window glass shown.

  1. Use a scan tool and check for Diagnostic Trouble Codes (DTCs) related to the rear window defogger switch, Cabin Compartment Node (CCN) and the Totally Integrated Power Module (TIPM). If no DTCs are found, go to Step #2. If any DTCs are found, repair as required, then proceed to Step #2.

    2.  
  2. Turn the ignition switch to RUN. Set the rear window defogger switch to ON. Rear window defogger operation can be checked by feeling the surfaces of the rear window glass. A distinct difference in temperature between the grid lines (5) and the adjacent clear glass should be detected within three to four minutes of operation.

    3.  
  3. If a temperature difference is not detected, use a 12-volt DC voltmeter and contact the rear glass heating grid terminal A (1) with the negative lead, and terminal B (2) with the positive lead. The voltmeter should read battery voltage. If the voltmeter does not read battery voltage, check the following:

    • Confirm the ignition switch is in RUN.
    • Confirm the rear window defogger switch is ON.
    • Confirm the EBL feed wire (3) is connected to the heating grid positive terminal and that there is continuity between the TIPM and the heating grid.
    • Confirm the EBL ground wire (6) is connected to the heating grid negative terminal and that there is continuity to ground.

    4.  
  4. If broken defogger grid lines or bus bars are suspected, use a 12-volt DC voltmeter and contact terminal A with the negative lead and each rear glass heating grid line at its mid-point C (4) with the positive lead. The voltmeter should read approximately 6 volts at each grid line mid-point. If the voltmeter does not read approximately 6 volts, repair the open grid line(s) or bus bar(s) (Refer to 08 - Electrical/8G - Heated/Cooled Systems/Heated Glass/GRID, Defogger - Standard Procedure) .

    5.  
  5. If the EBL system operation has been verified but the rear window defogger indicator does not illuminate, replace the A/C-heater control (Refer to 24 - Heating and Air Conditioning/Controls/CONTROL, A/C and Heater - Removal) .

    6.