When diagnosing a failed Passenger Presence System (PPS) pressure sensor on current models of the Buick Cascada, Envision, LaCrosse; Chevrolet Bolt, Camaro, Colorado, Corvette, Cruze, Malibu, Silverado, Spark, Suburban, Tahoe; Cadillac CT6, Escalade, XT5; GMC Acadia, Canyon, Sierra, and Yukon, the new sensor will come with a seat cushion as part of a service kit. Do not install the new pressure sensor without the new seat cushion. These two parts are part of a calibrated set. (Fig. 14)
TIP:Replace the Passenger Presence System as a complete assembly. Do not mix any of the old parts with the new parts.
Fig. 14
Recently, parts returned under warranty show that the sensor is being replaced while the seat cushion is not. If only the new sensor is installed, the repair is incomplete and the PPS may not operate properly. As a general rule, install all of the parts included in a service kit.
Each of the foam seat cushions are stamped with the date and time of production. If the sensor is replaced without the seat cushion and GM calls for the parts, it will be evident that the repairs were not completed properly.
Shown below is the PPS sensor (light green color) from the Cruze front passenger seat. (Fig. 15)
Fig. 15
PPS Operation
The Passenger Presence System is used to monitor the type of occupant that is sitting in the front passenger seat and communicates the status to the inflatable restraint sensing and diagnostic module. The inflatable restraint sensing and diagnostic module uses this information to determine whether to enable or suppress the deployment of the passenger instrument panel air bag. The Passenger Presence Module consists of an electronic control module, a pressure sensor mat in the seat, a harness, and passenger air bag on/off indicators.
The Passenger Presence Module transmits and receives a low-level electric field. The measured capacitance value of this field is used to determine the type of occupant sitting in the front passenger seat. If the measured capacitance is less than a calibrated value, the passenger instrument panel air bag is disabled. If the measured capacitance is greater than a calibrated value, the passenger instrument panel air bag is enabled.
Previous PPS systems had the pressure sensor located on top of the seat cushion. On the current PPS system, the pressure sensor is located under the seat cushion foam. (Fig. 16)
Fig. 16
TIP:The PPS is a calibrated system that requires rezeroing anytime the seat cushion trim attachments have been removed or the PPS has been replaced. Refer to the appropriate Service Information during any seat repairs.
– Thanks to Bill Taylor
