The inflatable restraint passenger presence system (PPS) continuously monitors for critical faults. If the PPS determines there is a fault internal to the electronic control unit (ECU) or sensor mat, the PPS will set DTC 056, turn the passenger air bag status indicator to OFF, and notify the sensing and diagnostic module (SDM) of a fault in the PPS through a non class 2 communications circuit. Other DTCs like DTC 034 or DTC 036 may set along with DTC 056. Diagnose all current DTCs before diagnosing DTC 056. The PPS, heated seat element, and seat bottom cushion is only service as a complete kit, which is a calibrated system and must be replaced as a complete unit. If a service kit was installed, DTC 056 will be set current and the Rezeroing Procedure must be performed before the DTC can be cleared.

Ignition voltage is between 9-16 volts.

DTC 034 or DTC 036 may set along with DTC 056. Diagnose all current DTCs before diagnosing DTC 056. This DTC 056 indicates that you have installed a service kit or have an internal fault to the ECU or sensor mat.

Schematic Reference

SIR Schematics

Connector End View Reference

SIR Connector End Views

Electrical Information Reference

1. Ignition ON, use the scan tool. Go to the passenger presence system (PPS) menu, then retrieve the DTCs. Refer to Passenger Presence System Flash Code Procedures . Verify DTC 034 or DTC 036 does not set.

⇒	If either DTC 034 or DTC 036 sets then refer to Diagnostic Trouble Code (DTC) List - Vehicle .

2. Check to see if the PPS has been replaced. Verify the correct PPS has been installed.

⇒	If the incorrect PPS was installed replace with the correct PPS. Then perform the Passenger Presence System Rezeroing .

3. Perform the Passenger Presence System Rezeroing and recheck for DTC 0056. Verify that DTC 0056 does not reset.

⇒	If DTC 0056 sets, then replace the PPS and rezero.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.