W202 Windshield Wiper starts itself

Wiper/Washer System Components
The Wiper/Washer System consists of the following electrical components:
• Accessory relay
• Heated washer nozzles w/XA7
• WASH NOZ 10A fuse
• Windshield washer fluid level switch
• Windshield washer pump motor
• Windshield wiper motor
• Windshield wiper motor module
• Windshield wiper/washer switch
• Wiper/washer switch 10A fuse
• Wiper motor 30A fuse

Wiper/Washer System Operation
The windshield wiper motor module is part of the windshield wiper motor cover and controls wiper motor operation. The accessory voltage supply circuit to the windshield wiper motor assembly is used to operate the wiper motor in all modes. The windshield wiper motor is a 2 speed motor and is operated at low speed in all modes except HIGH. The accessory voltage supply circuit to the windshield wiper/washer switch is used to supply the windshield wiper switch signal circuits. The windshield wiper switch signal circuit voltage levels to the wiper motor module determine the wiper motor operating mode.
When the wiper/washer switch is in the LOW position voltage is supplied through a 24K ohm resistor within the switch to the windshield wiper switch signal 2 circuit, and accessory voltage is supplied to the windshield wiper switch signal 1 circuit. The reduced voltage from the wiper switch signal 2 circuit and accessory voltage from the wiper switch signal 1 circuit causes the wiper motor module to close the wiper motor accessory voltage supply circuit to the wiper motor low speed terminal.

Do you know how to test automotive electrical circuit's using a DVOM - digital volt ohmmeter ? Do you know what a wiring diagram is an how to read one ? Free wiring diagrams here http://www.bbbind.com/free-tsb Enter vehicle info. year , make , model an engine size. Under system click on body & accessories ,then under subsystem click on wiper/ washer's . Click the search button then the blue link.

Windshield Wiper/Washer System Components
The windshield wiper/washer system consists of the following components:
• Windshield wiper/washer switch
• Windshield wiper motor
• Windshield washer pump
• Windshield washer relay
• Outside moisture sensor
• FRT WIPER 25A fuse
• W/S WASH 15A fuse
Windshield Wiper/Washer System Operation
Accessory voltage and ground is supplied to the windshield wiper motor and provides the power for operating the wiper motor and logic power to the wiper motor module. The WASH, MIST, LOW, and DELAY modes are controlled by the windshield wiper/washer switch through a series of internal resistors. The windshield wiper switch supply voltage circuit is a 12-volt reference from the wiper motor module to the wiper/washer switch, and the switch position determines the point on the resistor assembly where the reference voltage is applied. The windshield wiper switch signal 1 circuit supplies the voltage from the resistor assembly to the wiper motor module and the signal voltage determines the operating mode. High speed operation is controlled by the windshield wiper/washer switch through the windshield wiper switch high signal circuit. The windshield wiper switch high signal circuit is supplied 12 volts by the wiper motor module and when the wiper/washer switch is turned to the HIGH position the windshield wiper switch high signal circuit is grounded through the switch ground circuit. The windshield washer pump is controlled through the windshield wash relay. The windshield wash relay coil and switch is supplied battery positive voltage, and during WASH mode the wiper motor module grounds the washer relay control circuit energizing the relay. When the relay is energized battery positive voltage to the switch side of the relay is supplied to the washer pump control circuit.

The is the symptom of a defective wiper switch.

There are two relay's in the under hood fuse / relay box . Wiper relay an wiper relay 2 . Maybe one is bad . also check fuse #14 25 amp. Wiper fuse.Plus the BCM - body control module has a hand in making the wipers work . Are you familiar with automotive electronic control modules ?
The Wiper/Washer System consists of the following components:
• Windshield wiper/washer switch
• Body control module (BCM)
• Wiper micro relay
• Wiper 2 relay
• Wiper diode
• Windshield wiper motor
• Windshield washer pump
• Windshield washer nozzles
• Windshield washer solvent container
• Windshield wiper arm and blade assemblies
• Windshield wiper transmission
• WIP/WASH 10A fuse
• WIPER 25A fuse

Wiper/Washer System Description
The body control module (BCM) controls wiper motor low speed operation. The washer pump and high speed operation are controlled directly by the wiper/washer switch. The windshield wiper/washer switch supplies voltage on the signal circuits to the BCM for windshield wiper/washer operation. When WASH, MIST, DELAY, LOW, or HIGH is detected, the BCM energizes the wiper micro relay by suppling voltage to the relay coil. This allows battery voltage from the WIPER fuse to flow through the relay switched input then through the contacts and out the relay switched output to the wiper 2 relay switch contacts. Since the wiper 2 relay switch contacts are normally closed to the low speed circuit of the windshield wiper motor, the motor will operate at low speed.

Do you have any speed !

First you need a wiring diagram, free at http://www.bbbind.com/free_tsb.html Then you need a DVOM - digital volt ohm meter to test the circuit . Then if your not familiar with automotive electrical systems testing ,go on youtube an check out Electric Testing Techniques You Need to Know Also having a factory diagnostic trouble shooting chart would also be usefull . You could just start replacing parts , you mite get lucky . The wiper motor is a high fail part , so is the switch ..You could find the fuse is blown ! But fuse's don't usually blow without a reason . Short to ground , low resistance . ( high current flow) Also knowing how they work and what all is involved in making them work.
The Wiper/Washer System consists of the following components:
• Windshield wiper/washer switch
• Windshield wiper motor module
• Windshield wiper motor
• Windshield washer pump motor
• FRT/WPR/WSHR 25A fuse

Wiper/Washer System Operation
The windshield wiper motor module is part of the windshield wiper motor cover and controls wiper motor operation. The windshield wiper motor is a 2 speed motor and is operated at low speed in all modes except HIGH. The accessory voltage supply circuit to the windshield wiper motor assembly is used to operate the wiper motor in all of the low speed modes. The accessory voltage supply circuit to the windshield wiper/washer switch is used to supply the windshield wiper switch signal circuits and the wiper motor high speed circuit.
When the wiper/washer switch is in the LOW position voltage is supplied through a 24K ohm resistor within the switch to the windshield wiper switch signal 2 circuit, and accessory voltage is supplied to the windshield wiper switch signal 1 circuit. The reduced voltage from the wiper switch signal 2 circuit and accessory voltage from the wiper switch signal 1 circuit causes the wiper motor module to close the wiper motor accessory voltage supply circuit to the wiper motor low speed terminal.
Windshield wiper/washer system MIST operation is identical to LOW operation except that the MIST switch is a press and release type. When the wiper switch is moved to the MIST position and released, low speed wiper motor operation is started and will continue until 1 cycle is complete. If the wiper switch is moved to the MIST position and held, the windshield wiper motor will operate in the LOW mode until the switch is released.

Don't the wipers work in any mode ?
1
Did you review the Wiper/Washer System description and operation and perform the necessary inspections?
YES - Go to Step 2
NO - Go to Symptoms - Wiper/Washer Systems
2
Turn ON the ignition , with the engine OFF.
Operate the windshield wiper/washer switch through all the switch positions.
Does the windshield wiper/washer system operate normally?
YES - Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
NO - Go to Step 3
3
Turn OFF the ignition.
Disconnect the harness connector of the windshield wiper motor.
Turn the ignition ON, with the engine OFF.
Connect a test lamp from the accessory voltage circuit of the windshield wiper motor to a good ground.
Does the test lamp illuminate?
YES - Go to Step 4
NO - Go to Step 13
4
Connect a test lamp from the accessory voltage circuit to the ground circuit of the windshield wiper motor.
Does the test lamp illuminate?
YES - Go to Step 5
NO - Go to Step 14
5
Connect a test lamp from the signal 2 circuit of the windshield wiper switch to a good ground.
Press the windshield washer switch.
Does the test lamp illuminate?
YES - Go to Step 11
NO - Go to Step 6
Let me know if you make it this far and i will send rest of diagnostic's

When the windshield wiper / washer switch is turned to the OFF position while the wiper motor is somewhere in mid-cycle, the wiper motor module will continue to operate the wiper motor until the wipers reach the park position. If the ignition is turned off while the wipers are in mid-cycle, the wipers will stop immediately where they are. The wipers will park the next time the ignition is cycled to the ON position.

Schematic Reference: Wiper/Washer Schematics


1

Did you review the Wiper/Washer System Description and Operation and perform the necessary inspections?
Go to Step 2
Go to Symptoms - Wiper/Washer Systems

2

1. Turn the ignition ON.
2. Turn the windshield wiper/washer switch OFF.

Are the windshield wipers always on?
Go to Step 3
Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

3

Disconnect the windshield wiper/washer switch connector.
Are the windshield wipers always on?
Go to Step 4 if yes
Go to Step 7 if no

4

1. Disconnect the windshield wiper motor connector.
2. Test the windshield wiper switch signal 1 circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?
Go to Step 11
Go to Step 5

5

Test the windshield wiper switch signal 2 circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 11
Go to Step 6

6

Test the windshield wiper motor high speed circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 11
Go to Step 9

7

Inspect for poor connections at the windshield wiper/washer switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 11
Go to Step 8

8

Replace the windshield wiper/washer switch. Refer to Windshield Wiper and Washer Switch Replacement - On Vehicle in Steering Wheel and Column.
Is the repair complete?
Go to Step 11
--

9

Inspect for poor connections at the windshield wiper motor. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 11
Go to Step 10

10

Replace the windshield wiper motor. Refer to Windshield Wiper Motor Replacement .
Is the repair complete?
Go to Step 11
--

11

Operate the system in order to verify the repair.
Did you correct the condition?
The Wiper / Washer System consists of the following components:
?€¢
Windshield wiper / washer switch

?€¢
Windshield wiper system module / motor

?€¢
Windshield washer fluid pump

?€¢
Windshield washer fluid level switch

?€¢
Instrument panel cluster (IPC)

?€¢
ACC 15-amp fuse

?€¢
WSW 30-amp fuse

Usually a sign the park switch inside the motor is faulty.

Hi,
The 'stalk' that controls all these functions is faulty. Your truck SHOULD still be under warranty...Take it in.

GL,
Td

If both wipers don't move, could be the switch or the wiper motor.

Could be anything but based on experience the probability points to the self cancelling switching in the motor gearbox.