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DTC B1438 - Wiper Mode Select Switch Circuit Failure

WARNING: This page is about a different car, the 1997 Mercury Sable and 1997 Ford Taurus. However, it is still accessible from the selected car via links, so may be relevant.
  1. If DTC B1450 is retrieved with DTC B1438, go to step 8). If DTC B1450 is not retrieved with DTC B1438, go to next step.
  2. Using New Generation Star Tester (007-00500), request WPMODE PID from GEM. If PID reads open, go to next step. If PID does not read open, go to step 6).
  3. Disconnect multifunction switch connector C1. See Fig 1 . Turn ignition on. Measure voltage between multifunction switch connector C1, terminal No. 1 (Pink/Yellow wire) and GEM connector C3, terminal No. 4 (Pink/Yellow wire). See Figure . Measure voltage between multifunction switch connector C1, terminal No. 6 (Light Blue/Orange wire) and GEM connector C3, terminal No. 3 (Light Blue/Orange wire). If voltage is 4-6 volts on either circuit, replace multifunction switch and retest system. If voltage is not 4-6 volts on either circuit, go to next step.
    Fig 1: Identifying Multifunction Switch Connector C1 Terminals
    G95C34936Courtesy of FORD MOTOR CO.
  4. Disconnect GEM connector C3. Measure resistance between multifunction switch connector C1, terminal No. 1 (Pink/Yellow wire) and GEM connector C3, terminal No. 4 (Pink/Yellow wire). Measure resistance between multifunction switch connector C1, terminal No. 6 (Light Blue/Orange wire) and GEM connector C3, terminal No. 3 (Light Blue/Orange wire). If voltage is 5 ohms or less, on both circuits, go to next step. If resistance is not 5 ohms or less on both circuits, repair suspect circuit and retest system.
  5. Connect NGS tester to Data Link Connector (DLC). Turn ignition on. Wiggle wiper/washer harness between multifunction switch and GEM. If DTC B1438, B1450 or both are retrieved during wiggle test, repair intermittent open in circuits No. 684 (Pink/Yellow wire) and/or No. 680 (Light Blue/Orange wire) and retest system. If DTC B1438 is retrieved again, replace GEM and retest system.
  6. Disconnect GEM connector C3. Turn ignition on. Measure voltage between multifunction switch connector C1, terminal No. 1 (Pink/Yellow wire) and GEM connector C3, terminal No. 4 (Pink/Yellow wire). Measure voltage between multifunction switch connector C1, terminal No. 6 (Light Blue/Orange wire) and GEM connector C3, terminal No. 3 (Light Blue/Orange wire). If battery voltage exists on both circuits, go to next step. If battery voltage does not exist on both circuits, go to step 5).
  7. Turn ignition off. Disconnect multifunction switch connector C1. Turn ignition on. Measure voltage between multifunction switch connector C1, terminal No. 1 (Pink/Yellow wire) and GEM connector C3, terminal No. 4 (Pink/Yellow wire). Measure voltage between multifunction switch connector C1, terminal No. 6 (Light Blue/Orange wire) and GEM connector C3, terminal No. 3 (Light Blue/Orange wire). If battery voltage exists on both circuits, repair short to battery voltage in suspected circuit. If battery voltage does not exist on both circuits, replace multifunction switch and retest system.
  8. Using NGS tester, request WPMODE PID from GEM. If PID reads open, go to next step. If PID does not read open, go to step 12).
  9. Disconnect GEM C3 connector. Turn multifunction switch to HI position. Measure resistance between GEM C3 connector, terminal No. 16 (Dark Blue wire) and GEM C3 connector, terminal No. 4 (Pink/Yellow wire). If resistance is 5 ohms or less, go to next step. If resistance is not 5 ohms or less, go to step 11).
  10. Connect NGS tester to DLC. Turn ignition on. Wiggle wiper/washer harness between multifunction switch and GEM. If DTC B1438, B1450 or both are retrieved during wiggle test, repair faulty circuit and retest system. If DTC B1438, B1450 or both are not retrieved during wiggle test, check for DTC(s). See DIAGNOSTIC PROCEDURE  . If DTC B1438 is retrieved again, replace GEM and retest system.
  11. Disconnect multifunction switch connector C1. Measure resistance between GEM connector C3, terminal No. 16 (Dark Blue wire) and multifunction switch connector C1, terminal No. 4 (Pink/Yellow wire). If resistance is 5 ohms or less, replace multifunction switch and retest system. If resistance is not 5 ohms or less, repair circuit No. 682 (Dark Blue wire) and retest system.
  12. Disconnect GEM connector C3. Turn ignition on. Measure voltage between GEM connector C3, terminal No. 16 (Dark Blue wire) and ground. If battery voltage exists, go to next step. If battery voltage does not exist, go to step 10).
  13. Turn ignition off. Disconnect multifunction switch connector C1. Measure voltage between GEM connector C3, terminal No. 16 (Dark Blue wire) and ground. If battery voltage exists, repair short to battery voltage in circuit No. 682 (Dark Blue wire). If circuit No. 682 (Dark Blue wire) was shorted to battery voltage, GEM will be damaged internally. Repair short, replace GEM and retest system. If battery voltage does not exist, replace GEM and retest system.
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