Lincoln Town Car - Ford (Crown Victoria) - Mercury (Grand Marquis)
1988 Lincoln Town Car - Ford (Crown Victoria) - Mercury (Grand Marquis)
36-86-1 Window, Rear-Defroster 36-86-1
SECTION 36-86 Window, Rear-Defroster
SUBJECT PAGE
DESCRIPTION AND OPERATION 36-86-1
MAJOR SERVICE OPERATIONS
Grid Wire Repair 36-86-2
Lead Wire Terminal Repair 36-86-4
REMOVAL AND INSTALLATION
Control Assembly 36-86-2
Window 36-86-2
SUBJECT PAGE
SPECIAL SERVICE TOOLS 36-86-4
TESTING
Control Assembly Tests 36-86-1
Grid Wire Test 36-86-2
VEHICLE APPLICATION 36-86-1
VEHICLE APPLICATION Lincoln Town Car, Ford Crown Victoria/Mercury Grand Marquis.
DESCRIPTION AND OPERATION The heated rear window defroster system consists of a control assembly mounted on the climate control head, a series of grid lines baked on the inside surface of the rear window and system wiring. The grid lines consist of two layers. The first layer is brown in color as viewed from the exterior, and the second layer is silver in color as viewed from the interior. The control assembly has a lever spring-loaded to center position, to turn the system on or off, and a timercontrolled relay that turns off automatically after approximately 10 minutes of operation. If more than 10 minutes are required, the control can be reactivated for another 10 minutes by pushing the lever momentarily to the ON position. This operation can be repeated as required. When the lever is pushed to the ON position the normally open contacts in the control are mechanically closed, thus providing power from battery to the rear window grids, the indicator lamp, the heated outside mirror and also triggering the timing circuit. This contact will remain closed until the timer turns it off, the lever is pushed momentarily to the OFF position, or the ignition switch is turned to the OFF position.
Power for the rear window grids, the outside rearview mirror and the indicator lamp is supplied directly from the battery side of the starter motor relay through a fuse link which protects the circuit.
Power for the control timer comes from the accessory terminal of the ignition switch. This power is available whenever the ignition switch is in the RUN position. This circuit is protected by a fuse, located in the fuse panel.
FIGURE 1 - Wiring Diagram, Heated Rear Window:
TESTING
Control Assembly Tests
1. Ground pin 2 and connect a jumper wire between pins 4 and 3. Connect a 12-volt test lamp between pin 1 and ground (Fig. 1).
2. Apply power to pin 4. The test lamp should not light.
3. Momentarily actuate the lever to the ON position. The test lamp should come on and stay on after the lever returns to the normal position.
4. Test lamp should go off under any one or more of the following conditions:
^ If lever is moved to the OFF position.
^ Jumper wire between pins 3 and 4 is removed.
^ Approximately 10 minutes has elapsed.
1988 Lincoln Town Car - Ford (Crown Victoria) - Mercury (Grand Marquis)
36-86-2 Window, Rear-Defroster 36-86-2
Grid Wire Test
1. Using a strong lamp inside the vehicle, visually inspect the wire grid from the outside. A broken grid wire will appear as a brown spot.
2. Run the engine at idle. Set the control switch to ON. The indicator lamp should come on.
3. Working inside the vehicle with a 12-volt DC voltmeter such as Rotunda Digital Volt Ohm Meter 007-00001 or equivalent, contact the broad redbrown strips on the rear window (positive lead to battery side and negative lead to ground side). The meter should read 10-13 volts. A lower voltage reading indicates a loose ground wire (pigtail) connection at the ground side of the glass.
4. Contact a good ground point with the negative lead of the meter. The voltage reading should not change.
5. With the negative lead of the meter grounded, touch each grid line of the heated rear window at its midpoint with the positive lead. A reading of approximately 6-volts indicates that the line is good. A reading of zero volts indicates that the line is broken between the midpoint and the B+ side of the grid line. A reading of 12-volts indicates that the circuit is broken between the midpoint of the grid line and ground.
FIGURE 2 - Control Assembly Location:
REMOVAL AND INSTALLATION
Control Assembly
Removal and Installation Refer to Fig. 2
1. Remove knob from control lever.
2. Remove applique.
3. Remove screws retaining the climate control head to the instrument panel and remove the climate control head.
4. Remove control assembly from the climate control head assembly.
5. To install, reverse Steps 1 through 4.
Window Disconnect wire leads at each end of the glass (Fig. 3). Remove window. Refer to Section 43-11.
MAJOR SERVICE OPERATIONS
Grid Wire Repair
NOTE: A single break or any breaks that total more than 25 mm (1 inch) in one grid cannot be repaired. The window must be replaced. For breaks less than 25 mm (1 inch) long, use the following procedure: