F: Rear Window Will Not Defrost - Town Car

Pinpoint Test F - Rear Window Will Not Defrost - Town Car

NOTE: Ford DOES NOT provide a procedure to perform the following pinpoint test without the Rotunda New Generation Star (NGS) tester 007-00500 or equivalent.

F1 - Check Fuse 13 (10A)

- Turn ignition switch to RUN.
- Press heated back window switch and light.
- Read voltage at fuse junction panel fuse 13 (10A).

Is there voltage at the fuse?

YES GO to F7.
NO CHECK fuse D (40A) in power distribution box and fuse junction panel fuse 13 (10A). Note that fuse 13 will only have power when rear defroster is active. If fuse is good, GO to F2.

F2 - Test Heated Back Window Switch

- Connect Rotunda New Generation Star Tester 007-00500 or equivalent to data link connector.
- Request heated back window switch status PID RDEF_SW.

Does PID indicate heated back window switch and light active?

YES SERVICE heated back window switch and light for stuck switch. SERVICE circuit 688 (GY/LB) for short to ground. RETEST system.
NO GO to F3.

F3 - Test Heated Back Window Switch Light

- While holding heated back window switch and light, request heated back window switch status PID.

Does PID RDEF_SW indicate heated back window switch and light active?

YES GO to F4.
NO SERVICE heated back window switch and light. SERVICE circuit 688 (GY/LB) for open circuit. RETEST system.

F4 - Test Ignition Status

- Turn ignition switch to RUN.
- Request ignition switch status PID IGN_DD.

Does PID indicate ignition in run?

YES GO to F5.
NO CHECK fuses 6 (1OA) and 9 (5A). If both fuses are good, SERVICE circuits 294 (W/LB) and 1003 (GY/Y). RETEST system.

F5 - Test Heated Back Window Feed

- Disconnect lighting control module connector C4.
- Read voltage at pin C4-2 of connector.

Does voltage read B+?

YES GO to F6.
NO SERVICE circuit 175 (BK/Y). RETEST system.

F6 - Test Heated Back Window Output

- Using a jumper wire, short lighting control module pins C4-1 and C4-2.
- Read voltage at fuse 13 (10A).

Is voltage reading B+?

YES REPLACE lighting control module. RETEST system.
NO SERVICE circuit 18. RETEST system.

F7 - Test Heated Back Window Indicator

- Make sure that window defroster is still on.

Is window defroster indicator lit?

YES GO to F8.
NO SERVICE heated back window switch and light. RETEST system.

F8 - Test Voltage On Circuit 186 (BR/LB)

- Make sure that window defroster is still on.
- Read voltage on connector to radio isolator module circuit 186 (BR/LB).

Is voltage reading B+?

YES GO to F9.
NO SERVICE circuit 186 (BR/LB). RETEST system.

F9 - Test Radio Isolator Module Input

- Make sure that window defroster is still on.
- Read voltage on output of radio isolator module to window grid.

Is voltage reading B+?

YES GO to F10.
NO SERVICE radio isolator module. RETEST system.

F10 - Test Grounds

- Check for continuity from vehicle ground to circuit 57 (BK) of radio isolator module.

Is there continuity?

YES GO to F11.
NO SERVICE circuit 57 (BK). RETEST system.

F11 - Test Radio Isolator Module Ground

- Check for continuity to ground through the radio isolator module from the ground output to the window defroster.

Is there continuity?

YES REPLACE back window glass. RETEST system.
NO REPLACE radio isolator module. RETEST system.