Rear wiper stays on continuously , even when switched off at stack

Sounds like a wiring problem:
1. One of the wires attached to a pin in the connector attached to the wiring at the motor (not on the motor) may be corroded or have come loose, making intermittent contact, or
2. One of the wires in the harness between the motor and the switch is crimped somewhere around the tailgate and is intermittently opening, or
3. A bad motor ground wire connection at the tailgate.

Did you check the wiper relay's in the under hood fuse box ? There are two ,wiper run/park relay & wiper high low relay ! Also ,did you check fuse's ? fuse # 11 - 30amp location cental juction box . The wiper switch is a input to the GEM module . Generic electronic module . The module in most cases isn't the problem ! Learning how to test these electronic systems is , people do not know how to test so they just replace parts . What they should do is take the vehicle to ford certified Technician who has the knowledge and testing equipment to find an fix it .

The generic electronic module (GEM) receives inputs from the following:

• multifunction switch
• anti-lock brake control module (vehicle speed signal [VSS])
• ignition switch

The GEM uses these inputs to control the outputs to the following:

• windshield wiper high/low relay
• windshield wiper run/park relay
• windshield washer relay
• rear wiper motor relay
• rear window washer relay
• 
  GEM Diagnostic Trouble Code (DTC) Index DTC Description Source Action B1240 Wiper Washer Rear Pump Relay Circuit Failure GEM GO to Pinpoint Test K . B1241 Wiper Washer Rear Pump Relay Circuit Short to Battery + GEM GO to Pinpoint Test K . B1342 ECU is Defective GEM CLEAR the DTCs. REPEAT the GEM self-test. If DTC B1342 is retrieved, INSTALL a new GEM. REFER to Section 419-10 . B1431 Wiper Brake/Run Relay Circuit Failure GEM If the windshield wipers are inoperative, GO to Pinpoint Test B .
  If the windshield wipers stay on continuously, GO to Pinpoint Test C . B1432 Wiper Brake/Run Relay Circuit Short to Battery GEM GO to Pinpoint Test B . B1434 Wiper Hi/Low Speed Relay Coil Circuit Failure GEM GO to Pinpoint Test D . B1436 Wiper Hi/Low Speed Relay Coil Circuit Short to Battery GEM GO to Pinpoint Test D . B1438 Wiper Mode Select Switch Circuit Failure GEM If the windshield wipers are inoperative, GO to Pinpoint Test B .
  If both the windshield and rear window wipers are inoperative, GO to Pinpoint Test L . B1441 Wiper Mode Select Switch Circuit Short to Ground GEM GO to Pinpoint Test C . B1446 Wiper Park Sense Circuit Failure GEM If the intermittent windshield wiper speed does not operate correctly, GO to Pinpoint Test E .
  If the speed dependent interval mode does not operate correctly, GO to Pinpoint Test G .
  If both windshield and rear wipers are inoperative, GO to Pinpoint Test L . B1450 Wiper Wash/Delay Switch Circuit Failure GEM If the intermittent windshield wiper speed does not operate correctly, GO to Pinpoint Test E .
  If the wash and wipe function does not operate correctly, GO to Pinpoint Test F .
  If both the windshield and rear wipers are inoperative, GO to Pinpoint Test L . B1453 Wiper Wash/Delay Switch Circuit Short to Ground GEM If the windshield wipers stay on continuously, GO to Pinpoint Test C .
  If the wash and wipe function does not operate correctly, GO to Pinpoint Test F . B1458 Wiper Washer Pump Motor Relay Circuit Failure GEM GO to Pinpoint Test F . B1460 Wiper Washer Pump Motor Relay Coil Circuit Short to Battery GEM GO to Pinpoint Test F . B1473 Wiper Low Speed Circuit Motor Failure GEM If the windshield wipers are inoperative, GO to Pinpoint Test B .
  If the windshield wipers do not operate at high or low speed correctly, GO to Pinpoint Test D .
  If the intermittent windshield wiper speed does not operate correctly, GO to Pinpoint Test E . B1475 Accessory Delay Relay Contact Short to Battery GEM REFER to Section 501-11 . B1476 Wiper High Speed Circuit Motor Failure GEM If the windshield wipers are inoperative, GO to Pinpoint Test B .
  If the windshield wipers do not operate at high or low speed correctly, GO to Pinpoint Test D .
  If the intermittent windshield wiper does not operate correctly, GO to Pinpoint Test E . B1611 Rear Wiper Mode Switch Circuit Failure GEM GO to Pinpoint Test H . B1614 Rear Wiper Mode Switch Circuit Short to Ground GEM GO to Pinpoint Test I . B1820 Rear Wiper Motor Up Relay Circuit Short to Battery + GEM GO to Pinpoint Test H . B1839 Rear Wiper Motor Circuit Failure GEM GO to Pinpoint Test H . - All other DTCs. GEM REFER to Section 419-10

I think you need to get your junction box checked.

Most likely it's your rear wiper motor, unless there's a short somewhere in your wiring leading to your motor. It's a little tricky to get to, to replace it, but very doable. If you don't want to replace it then you can just unplug the connecter right on the motor to make it stop.

To take the motor off you'll have to take off the rear hatch interior plastic cover, remove a few bolts inside, and then take off the wiper and arm to remove a large bolt. I have a 1999 grand cherokee and had three bad rear wiper motors with different problems. I just gave up and don't use it anymore :(

Also, if you're really bad with cars, you can just take the whole wiper and arm off until someone else can fix it :)

Wow, the wiper still goes with the battery disconnected, that's amazing! Just joking ;-) Seriously, it sounds like it could be a short in the switch to control the wiper or a wire has shorted causing the wiper to stay on. Probably, if you replace the switch, the problem will be solved. If you know someone with the same type of car, you could "borrow" their switch and connect it to your car to see it that is the problem. I hope this helps.

You will have to first check the wiper motor relay in case it has become fused and stuck.
After that, then you need to check the switch operation on the wiper stalk.

wiper motors have a circuit, always 12V on, which returns them to the rest position even after the switch is in OFF position. I would suspect a malfunction in that circuit. it is inside the motor body and not replaceable other than by replacing the whole wiper motor.

Back window wiper switches/levers are tricky, especially on German-brand automobiles.
Just make sure that the lever/switch is on 'O' or OFF. I overlooked this once on an Opel Astra, and mistook it for the signal lever. Move the switch to all positions to ensure that there is no damage to the physical contacts or electronic controllers of the wiper.
If the wiper cycles even in off position, the controller or motor will need to be replaced.

Every wiper motor has a switch built into it that is supposed to shut off the wiper when it reaches it's 'home' position. Apparently that is getting stuck. If you're brave you can try taking it a apart and check it out, otherwise you probably need a new motor.

Principles of Operation
Operation of the windshield wiper and washer is controlled by the front wiper/washer amplifier assembly. The front wiper/washer amplifier input comes from the multifunction switch by means of a voltage divider circuit. A constant voltage is applied to the multifunction switch by the front wiper/washer amplifier. When the multifunction switch is moved into the LO, HI, or intermittent position, the voltage is directed through a series of resistors. This results in various voltages being returned to the module for each switch position. The module then grounds the appropriate circuit, based on the voltage signal received back from the multifunction switch. This causes the wipers to run intermittently, or at the appropriate speed. Voltage is supplied to the wiper motor by the CJB fuse F46 (20A).
When the multifunction switch wash button is depressed, it bypasses all of the resistors returning a full voltage signal to the module. The module then grounds the appropriate circuits to operate the windshield washer pump for as long as the switch is depressed. The windshield wiper speed is dependent on the position of the windshield wiper/washer switch.
Voltage for the windshield washer pump is also provided by CJB fuse F46 (20A).
Operation of the rear wiper and washer is controlled by the rear wiper/washer switch.
Voltage is supplied to the rear window wiper motor by the fuse junction panel fuse F44 (10A).
The rear window wiper motor ground is made or broken by the rear wiper/washer switch. When the rear wiper/washer switch is moved into the WIPER position, it grounds the rear window wiper motor circuit, causing the rear window wiper motor to run once every 10-15 seconds.
Voltage to the rear washer pump motor is also supplied by the CJB fuse F44 (10A). The rear washer pump is directly controlled by the rear wiper/washer switch which makes or breaks the ground for the washer pump motor, depending upon its position.
If the vehicle is equipped with a movable liftgate glass, a liftgate glass switch is utilized to prevent rear window wiper operation when the liftgate glass is open. This same switch also causes the rear window wiper to drop down approximately three inches when the liftgate glass latch is released.
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• The wipers stay on continuously — rear wiper

• Circuit.
• Rear wiper/washer switch.

• GO to Pinpoint Test L .

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Measure the resistance between rear wiper/washer switch C288 pin 6, component side and rear wiper/washer switch C288 pin 2, component side.

• Is the resistance less than 5 ohms with the switch depressed, and greater than 10,000 ohms with it released?

Yes GO to L2 .
No INSTALL a new rear wiper/washer switch. TEST the system for normal operation.

Measure the resistance between rear wiper/washer switch C288 pin 6, circuit WB08 (BU/YE), harness side and ground.

• Is the resistance greater than 10,000 ohms?

Yes INSTALL a new rear wiper /washer switch. TEST the system for normal operation.
No REPAIR circuit WB08 (BU/YE). TEST the system for normal operation.