Diagnosing False Wipes (Automatic Wiper Only)

WARNING: This page is about a different car, the 2020 Jeep Renegade. However, it is still accessible from the selected car via links, so may be relevant.

False wipes, are unnecessary wipes that occur when the control knob of the right multifunction switch is in one of the two automatic wiper sensitivity positions and no rain or moisture is apparent within the wipe pattern on the windshield glass. Because this system is designed to operate whenever it detects moisture, if the switch is in one of the automatic wiper sensitivity positions any road spray, bug splatters or mist from passing cars or trucks may occasionally cause the wipers to cycle. These are normal characteristics of this system and are not false wipes.

False wipes generally are the result of foreign material or flaws that interfere with the system optics. The optics for this system allow the Light Rain Sensor Module (LRSM) to precisely transmit several InfraRed (IR) light beams and monitor the intensity of these beams reflected from the outer surface of the windshield glass to determine the presence of moisture. The sensitivity of this system is such that anything that distorts the focus or intensity of the IR light beams or impacts the ability of the photo diodes within the LRSM to see and accurately measure these light beams can result in the LRSM logic misinterpreting the resulting input data as moisture on the windshield. The optics for this system include the lenses of the LRSM, the adhesive silicone gelatin (SilGel) layer that bonds the LRSM to the inside of the windshield and the windshield glass.

The following procedure should only be used if false wipe occurrences are frequent and persistent. Perform diagnosis of the wiper system, the right multifunction switch and microcontroller of the Body Control Module (BCM) and the LRSM using a diagnostic scan tool and the appropriate diagnostic procedures before performing the following:

NOTE:

The LRSM mounting bracket is serviced as a unit with the windshield glass. If either the bracket or the glass is ineffective or damaged, the entire LRSM bracket and windshield glass unit must be replaced. Also, if the LRSM is removed from the mounting bracket for any reason, the integrity of the adhesive silicone gelatin (SilGel) layer of the LRSM will be compromised and the silicone gelatin pad must be replaced with a new unit.

Carefully inspect the outer surface of the windshield glass for physical damage, including scratches, cracks or chips in the vicinity of the LRSM mounting bracket. Scratches, cracks or chips in the windshield glass outside the area of the LRSM mounting bracket lenses will not cause false wipes. If OK, go to Step 2 . If not OK, replace the damaged windshield.
From the outside of the windshield glass, carefully inspect the adhesive layer between the windshield glass and the LRSM bracket for any large voids (air pockets). If an adhesive void greater than about 1 millimeter (0.04 inch) is observed, replace the flawed silicone gelatin pad. If OK, go to Step 3 .
Lightly pull the LRSM away from the windshield bracket to confirm that both sides of the spring steel LRSM mounting band are fully engaged with the mounting bracket on the inside of the windshield glass. If OK, go to Step 4 . If not OK, install the LRSM mounting band onto the bracket as required.
Remove the LRSM from the mounting bracket. Carefully inspect the LRSM mounting bracket for any physical damage and inspect the windshield glass area within the LRSM mounting bracket for contamination. If OK, go to Step 5 . If contaminated, clean any foreign material from the windshield glass using rubbing alcohol and a lint-free cloth. If damaged, replace the damaged LRSM bracket and windshield as a unit.
Carefully replace the LRSM with a new unit. Refer to MODULE, LIGHT RAIN SENSOR, REMOVAL AND INSTALLATION .