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DTC B1438: Wiper Mode Select Switch Circuit Failure

  1. Check For DTCs  - If DTC B1450 is retrieved with DTC B1438, go to step 7). If DTC B1450 is not retrieved with DTC B1438, go to next step.
  2. Check PID  - Access WPMODE PID from GEM. If PID reads OPEN, go to next step. If PID does not read open, go to step 5).
  3. Check Wiper Switch Circuits  - Disconnect multifunction switch connector C259. See Fig 1 . Turn ignition on. Measure voltage between ground and multifunction switch connector C259, terminal No. 1 (Dark Blue/ White wire), and then connector C259, terminal No. 6 (Orange wire). If voltage is 4-6 volts on both circuits, replace multifunction switch and retest system. If voltage is not 4-6 volts on both circuits, go to next step.
    Fig 1: Identifying Multifunction Switch Connector C259 Terminals
    G95J34933Courtesy of FORD MOTOR CO.
  4. Check Orange & Dark Blue/White Wires For Open  - Disconnect GEM connectors C233 and C234. See Figure . Measure resistance of Dark Blue/White wire between multifunction switch connector C259, terminal No. 1 and GEM connector C233, terminal No. 19. Also measure resistance of Orange wire between multifunction switch connector C259, terminal No. 6 and GEM connector C234, terminal No. 10. If resistance 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. Check Orange & Dark Blue/White Wires For Short  - Disconnect GEM connectors C233 and C234. Reconnect multifunction switch. Turn ignition on. Measure voltage between ground and GEM connector C233, terminal No. 19 (Dark Blue/White wire) and connector C234, terminal No. 10 (Orange wire). If battery voltage exists, go to next step. If battery voltage does not exist, recheck DTCs. If DTC B1438 returns, replace GEM. Restore electrical connections and check system operation.
  6. Check Multifunction Switch For Short  - Turn ignition off. Disconnect multifunction switch connector C259. Turn ignition on. Measure voltage between ground and GEM harness connector C234, terminal No. 10 (Orange wire) and GEM connector C233, terminal No. 19 (Dark Blue/White wire). If voltage exists on either wire, repair wire for short to voltage. If voltage does not exist on either wire, replace multifunction switch.
  7. Check PID  - Access GEM PID WPMODE. If PID reads OPEN, go to next step. If PID does not read open, go to step 10).
  8. Check Brown/White Wire For Open  - Disconnect GEM connector C233. Turn multifunction (wiper) switch to HI position. Measure resistance between GEM connector C233, terminal No. 14 (Brown/White wire) and GEM connector C234, terminal No. 10 (Orange wire). If resistance is 5 ohms or less, go to next step. If resistance is greater than 5 ohms, recheck for DTCs. If DTC B1438 returns, replace GEM. Restore electrical connections and check system operation.
  9. Check Multifunction Switch  - Disconnect multifunction switch connector C259. Measure resistance between GEM connector C233, terminal No. 14 (Brown White wire) and multifunction switch connector C259, terminal No. 4 (Brown/White wire). If resistance is 5 ohms or less, replace multifunction switch. Restore electrical connections and check system operation. If resistance is not 5 ohms or less, repair open Brown/White wire.
  10. Check Brown/White Wire For Short  - Disconnect GEM connector C233. Turn ignition on. Measure voltage between GEM connector C233, terminal No. 14 (Brown/White wire) and ground. If battery voltage exists, go to next step. If battery voltage does not exist, recheck for DTCs. If DTC B1438 returns, replace GEM. Restore electrical connections and check system operation.
  11. Check Wiper Switch  - Turn ignition off. Disconnect multifunction switch connector C259. Measure voltage between GEM connector C233, terminal No. 14 (Brown/White wire) and ground. If battery voltage does not exist, replace multifunction switch. Restore electrical connections and check system operation. If battery voltage exists, repair short to power in Brown/White wire. If Brown/White wire was shorted to power, GEM will be damaged internally. Repair short, replace GEM. Restore electrical connections and check system operation.
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