The rear wiper on my '17 Cherokee "misses" the center of the window. The blade is new (factory), and the arm has never been damaged. It doesn't skip or drag or make any noise, and when I watch if work, it looks to be in contact with the window, but apparently it's not in contact enough to not leave the middle untouched. I'm kind of at a loss to figure this out. I'm contemplating buying a new arm for it, but am hesitant to make that leap until I see if anyone here has any ideas first.
Thoughts? Suggestions?
Thanks!

 

It looks like you have mineral or ice buildup on your window directly below the sprayer nozzle. is your wiper blade clean?
Go to a gas station and clean the back winddow.

 

The window has been cleaned (either by me at home, or at the car wash) a number of times. The wiper blade is new and clean, and it continues to somehow miss this spot.

 

it almost looks like yours might be distorted in the middle pivot, see the gap in mine. yours iff its partially lifted there may be why. your plastic secure cover thing looks like it may have some where on it, is the bolt tight.

Is your blade this length style

Is your spring at the base still there

 

The wiper blade does appear to lay flat on the window for it's entire length (it's kind of hard to see in this picture that I just now took). The spring is in place. The wiper blade is a OEM blade. I checked the nut holding the arm, and it is tight, wouldn't budge when I tried to tighten it down any more

 

youre using a 5 year old wiper blade on a crossover rear window, get a new darn blade. This is our 3rd one. Rear blades face a lot more abrasive things, snow, frozen stuff etc. its flat worn out. you want to replace it before you start etching your glass with metal frame parts.

Get a new blade from walmart and report results. I think it will fix it.

 

i can also see in the pic the blade is worn in terms of "rolling" its lost its ability to hold a blade shape over a swipe and im guessing mid sweep is the worst angle for it to be able to maintain and thats why it doesnt work there. ez-pz

 

I did do the obvious thing and replaced the blade. The blade is less than 6 months old. When this problem cropped up, I bought an aftermarket blade and it didn't fix the problem, so I went to the dealer and bought an OEM blade, which is what is in the photo. These were not the first replacement blades for that window, and they won't be the last, but changing the blades doesn't seem to be the solution.

 

can you copy a picture of my blade on your back screen? I see some things but I cant tell if its just perspective difference. try and get the angle and level the same, close is all you need
your arm almost looks closer to the glass

 

 

the only thing I can remotely tell is different/strange. Not sure what that means if anything, investigate

 

I see what you're talking about.
I bit the bullet and bought a whole new wiper arm. It didn't seem to fix the problem. I'm resigned to just living with this (it's not the end of the world).

 

is your splined shaft thing that the wiper pivots on Square? square to the window/everything? Im almost wondering if you have some install issue where the motor is not shimed or something correct or the glass is installed off kilter. otherwise, is your glass proper contour? There can only be so many casuses can you turn the wiper on and then go to the wiper arm and hold the base and feel the rotation, see if it has any hiccups or see if its loose. loose at 12 o clock maybe. or wiggle etc i can try ours. also, maybe even pull a fuse while its at 12 and see how its angled or something

 

Rear Wiper System

REAR WIPER SYSTEM

============================================The rear wiper motor operation is controlled by the Body Control Module (BCM), which uses relays soldered onto the BCM Printed Circuit Board (PCB) to control rear wiper system operation for energizing or de-energizing the rear wiper motor. The BCM uses internal programming and electronic messages received over the Controller Area Network (CAN) data bus received from the right (wiper) multifunction switch through the microcontroller internal to the Steering Column Control Module (SCCM) and a hard wired input from the rear wiper motor park switch to provide the rear wiper and washer system operating modes.

The rear wiper motor park switch is a single pole, single throw, momentary switch within the wiper motor that is mechanically actuated by the wiper motor transmission components. The park switch alternately closes and opens a voltage signal for the rear wiper motor electronic control logic circuitry of the BCM. The park switch is normally an open circuit when the rear wiper blade is in the parked position, and is connected to fused ignition output when the rear wiper blade is anywhere except parked.

This park switch input allows the electronic logic circuits of the BCM to control all of the electronic features of rear wiper motor operation and to keep the motor energized long enough to complete its current wipe cycle and park the wiper blade at the base of the glass after the status of the rear wiper system or the ignition switch transitions to Off. The internal BCM circuitry pulls the park switch sense input to ground when the switch is open so that the microcontroller sees a ground when the wiper blade is parked.

The rear wiper motor is grounded at all times through a take out with an eyelet terminal connector in the body wire harness that is secured to a ground location in the passenger compartment. The automatic resetting circuit breaker protects the motor from overloads. The rear wiper motor transmission converts the rotary output of the wiper motor to the back and forth wiping motion of the rear wiper arm and blade on the liftgate glass.

The hard wired inputs and outputs of the rear wiper motor may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the rear wiper motor or the electronic controls and communication between other modules and devices that provide some features of the rear wiper and washer system. The most reliable, efficient and accurate means to diagnose the rear wiper motor or the electronic controls and communication related to rear wiper motor operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
================================================== =========

ear Wiper And Washer System

DIAGNOSIS AND TESTING - REAR WIPER AND WASHER SYSTEM

WARNINGTo avoid serious or fatal injury on vehicles equipped with airbags, disable the Supplemental Restraint System (SRS) before attempting any steering wheel, steering column, airbag, Occupant Classification System (OCS), seat belt tensioner, impact sensor or instrument panel component diagnosis or service. Disconnect and isolate the battery negative (ground) cable, then wait two minutes for the system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the SRS. Failure to follow these instructions may result in accidental airbag deployment.



If the rear wiper motor operates, but the wiper motor output shaft does not move, replace the ineffective rear wiper motor. If the washer pump/motor operates, but no washer fluid is dispensed on the glass; or, if the wiper operates, but chatters, lifts, or does not clear the glass, clean and inspect the rear wiper and washer system components as required. (Refer to Electrical/8R - Wipers/Washers - Cleaning) and (Refer to Electrical/8R - Wipers/Washers - Inspection).

The hard wired rear wiper and washer system circuits and components may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin out information and location views for the various wire harness connectors, splices and grounds.

However, conventional diagnostic methods will not prove conclusive in the diagnosis of the electronic controls and communication between other modules and devices that provide some features of the rear wiper and washer system. The most reliable, efficient and accurate means to diagnose the rear wiper and washer system or the electronic controls and communication related to rear wiper and washer system operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.


NOTEThe rear wiper and washer switches are integral to the right (wiper) multifunction switch in the Steering Column Control Module (SCCM). The multifunction switches communicate with the SCCM microcontroller. The SCCM microcontroller is a gateway to the Controller Area Network (CAN) data bus and communicates with the Body Control Module (BCM) over the CAN bus. The BCM controls rear wiper motor operation through the rear wiper relay that is integral to the Printed Circuit Board (PCB) within the BCM.Before performing any of the following tests, determine whether the other functions of the SCCM multifunction switches are operational. If other SCCM switch functions are ineffective, diagnose and repair that problem before attempting to repair the rear wiper and washer system.


REAR WIPER AND WASHER SYSTEM DIAGNOSIS CONDITION POSSIBLE CAUSES CORRECTION WIPER MOTOR DOES NOT OPERATE IN ANY SWITCH POSITION 1. Ineffective motor ground circuit. 1. Test and repair open wiper motor ground circuit if required. 2. Ineffective motor feed circuits. 2. Test and repair motor feed circuit between BCM and rear wiper motor if required. 3. Ineffective SCCM inputs or outputs. 3. Use a diagnostic scan tool and the appropriate diagnostic information for further SCCM diagnosis. 4. Ineffective BCM inputs or outputs. 4. Use a diagnostic scan tool and the appropriate diagnostic information for further BCM diagnosis. 5. Ineffective wiper motor. 5. Test and replace open or shorted wiper motor if required. WIPER DOES NOT PARK CORRECTLY 1. Ineffective wiper motor park switch input circuit. 1. Test and repair wiper park switch input circuit between BCM and rear wiper motor if required. 2. Ineffective BCM inputs or outputs. 2. Use a diagnostic scan tool and the appropriate diagnostic information for further BCM diagnosis. 3. Ineffective wiper motor park switch. 3. Test and replace rear wiper motor if required. WIPER MOTOR OPERATES SLOWLY 1. Ineffective wiper motor. 1. Check amperage draw with wiper arm disconnected from rear wiper motor output shaft. Correct draw should be about 6 amperes. If incorrect, refer to the appropriate Possible Cause that follows: 2. Amperage draw too low. 2. Test and repair shorted rear wiper motor signal and fused ignition switch output (run - accessory) circuits if required. 3. Amperage draw too high. 3. With wiper arm disconnected from wiper motor output shaft check for binding between output shaft and motor output shaft housing. If binding is detected, lubricate if required. If no binding is detected, replace the wiper motor if required. WASHER PUMP DOES NOT OPERATE 1. Ineffective washer pump ground circuit. 1. Test and repair open washer pump ground circuit if required. 2. Ineffective washer pump feed circuit. 2. Test and repair washer pump feed circuit between BCM and washer pump if required. 3. Ineffective SCCM inputs or outputs. 3. Use a diagnostic scan tool and the appropriate diagnostic information for further SCCM diagnosis. 4. Ineffective BCM inputs or outputs. 4. Use a diagnostic scan tool and the appropriate diagnostic information for further BCM diagnosis. 5. Ineffective washer pump. 5. Test and replace open or shorted washer pump if required.Copyright ©2022 by Chilton, an imprint of Cengage Learning

The rear wiper blade and wiper arm should be inspected periodically, not just when wiper performance problems are experienced. This inspection should include the following points:
CAUTIONDo not allow the wiper arm to spring back against the glass without the wiper blade in place or the glass may be damaged.

1. Carefully inspect the wiper blade for any indications of worn or uneven edges (1), foreign material deposits (2), hardening or cracking (3), deformation or fatigue (4), or splitting (5). Inspect the wiper blade support components and the wiper arm for damage (6). If the wiper arm and blade are contaminated with any foreign material, clean them and the glass as required. (Refer to Electrical/8R - Wipers/Washers - Cleaning). If the wiper blade or arm is damaged, replace it with a new unit. Do not attempt to repair a wiper arm or blade that is damaged or corroded.
   
2. Carefully lift the wiper blade off of the glass. Note the action of the wiper arm hinge. The wiper arm should pivot freely at the hinge, but with no lateral looseness evident. If there is any binding evident in the wiper arm hinge, or there is evident lateral play in the wiper arm hinge, replace the wiper arm.
   
   
   
   
   
3. Once proper hinge action of the wiper arm is confirmed, check the hinge for proper spring tension. The spring tension of the wiper arm should be sufficient to cause the rubber squeegee to conform to the curvature of the glass. Replace a wiper arm if it has insufficient spring tension to maintain contact between the squeegee and the glass.
   
4. After cleaning and inspecting the wiper components and the glass, if the wiper blade still fails to clear the glass without smearing, streaking, chattering, hazing, or beading, replace the wiper blade.
   

 

Hi, It could be that the wiper mounting nub to which the wiper arm & blade is attached is bent or mal-aligned. Mine did pretty much the same but I fixed it somewhat. In my case I knew the cause. I had my hatch opened and started to drive out of my garage until I heard a thud! The garage door caught the wiper and bent the wiper assembly. The wiper motor is mounted directly behind the glass and was knocked off kilter. I got to work better but not 100%. Before I fixed it somewhat, the blade hardly touched the window. In your case unless you can remember something which could have damaged the wiper motor assembly, I would not rule out that a mechanical car wash bent the assembly. I don't do car washes as years ago I got scratches on a new Benz and no more. Just a thought.