My rear wiper on my 03' 4runner will wipe one time and just get stuck there and do nothing. I've replaced the rear wiper motor and the front/rear wiper switch on the steering wheel already.

Did you check fuse's & relays ?
Rear Window Wiper Operation
The rear wiper motor is controlled by the SJB. The SJB supplies power to the rear wiper motor from the integrated rear wiper relay. The SJB will activate the relay when all of the following conditions are met:

• Ignition switch is in the ON position
• Liftgate glass and liftgate are closed
• Multi-function switch is in the ON or intermittent position

The SJB also supplies voltage to the rear wiper motor from SJB fuse 21 (15A) when the ignition switch is in the ON position. This power feed is used to continue the wipe cycle when the multi-function switch is turned to the OFF position. The SJB receives inputs from the multi-function switch that applies ground to the low speed wipe input or applies ground to the intermittent wipe input. When either of these circuits are grounded, the SJB activates the integrated rear wiper relay and power is supplied to the rear wiper motor to move the rear wiper motor from the park position. An internal switch in the rear wiper motor then moves to the run position which connects the accessory relay power to the rear wiper motor. When the rear wiper motor returns to the park position, the internal switch in the rear wiper motor moves back to the park position. If the multi-function switch is in the ON position, the rear wiper relay is still activated, power is supplied to the rear wiper motor, and the wipe cycle starts again. If the multi-function switch is in the intermittent position, the rear wiper relay does not activate until the predetermined dwell time has elapsed, at which time the SJB activates the rear wiper relay and the wipe cycle starts again. The SJB is the smart junction box .(computer )

Rear Washer System
The SJB supplies power to the rear washer pump from fuse 21 (15A) when the ignition switch is in the ON or ACC position. The rear washer pump receives ground from the multi-function switch when the wash function is turned ON. The multi-function switch also signals the SJB when the rear wash is activated and the SJB then activates the rear wiper.

Sounds like the wiper switch is failing. It's not uncommon.

What make , model & year vehicle ? The rear washer shouldn't have anything to do with the front one , nor the wiper motor for that matter .

Do you know how these wipers Work / what controls them ? Do you know what a smart junction box is ?
Rear Window Wiper Operation
The rear wiper motor is controlled by the SJB. The SJB supplies power to the rear wiper motor from the integrated rear wiper relay. The SJB will activate the relay when all of the following conditions are met:

• Ignition switch is in the ON position
• Liftgate glass and liftgate are closed
• Multifunction switch is in the ON or INTERMITTENT position

The SJB also supplies voltage to the rear wiper motor from SJB fuse 21 (10A) when the ignition switch is in the ON position. This power feed is used to continue the wipe cycle when the multifunction switch is turned to the OFF position. The SJB receives inputs from the multifunction switch that applies ground to the low speed wipe input or applies ground to the intermittent wipe input. When either of these circuits are grounded, the SJB activates the integrated rear wiper relay and power is supplied to the rear wiper motor to move the rear wiper motor from the PARK position. An internal switch in the rear wiper motor then moves to the RUN position which connects the accessory relay power to the rear wiper motor. When the rear wiper motor returns to the PARK position, the internal switch in the rear wiper motor moves back to the PARK position. If the multifunction switch is in the ON position, the rear wiper relay is still activated, power is supplied to the rear wiper motor, and the wipe cycle starts again. If the multifunction switch is in the INTERMITTENT position, the rear wiper relay does not activate until the predetermined dwell time has elapsed, at which time the SJB activates the rear wiper relay and the wipe cycle starts again.

Do you know what DTC'S - diagnostic trouble codes are ?
Smart Junction Box (SJB) Diagnostic Trouble Code (DTC) Index DTC Description Source Action B1244 Wiper Rear Motor Run Relay Coil Circuit Failure SJB If the rear wiper is inoperative, Go To Pinpoint Test B . If the rear wiper is always ON, Go To Pinpoint Test D . B1245 Wiper Rear Motor Run Relay Coil Circuit Short to Battery SJB Go To Pinpoint Test B . B1614 Wiper Rear Mode Select Switch Circuit Failure SJB Go To Pinpoint Test D .
Did you have it checked for DTC'S ?

Sounds like the switch .

sorry so be the barer of bad news wiring loom fault

Try replacing the wiper switch.

No solution sorry - mine have done exactly the same - will wipe front screen if you mess with the stalk - rear wiper works when you push the stalk forwards or backwards but no washer to either - have you found a solution? Kind regards - Andy

Sounds like a problem within the wiper motor not turning off at rest or not reaching it's rest point to be able to turn itself off, probably needs a new motor. Disconnecting it should have no relation to the front washer operation, you can confirm this by reconnecting the wiper motor to try.

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Check for a bent arm, pos. was bent by scruber.  Or was it on during the wash? it may have been stuck at one point and the wiper motor still turning, and is now out of time. Arm position to motor shaft position.