DTC 38 - Low Pressure Detected, Sensor Open Or Short To Ignition

Every time ignition switch is turned to ON position, SDM performs a series of self tests to check for internal malfunctions. If no internal faults are detected, SDM measures voltages in ignition 1, 36 VLR (back-up power supply), and deployment loop circuits. If all of these circuit voltages are within pre-defined parameters, SDM will measure resistance of inflator modules. Next phase of self diagnostics is Continuous Monitoring. During this phase, SDM measures voltage at B8 terminal and compares it to voltage at B9 terminal. SDM will set code 38 if voltage differential falls below a pre-determined limit for about 1/2 second. If this fault occurs intermittently, most probable causes are a poor connection at SDM or passenger-side inflator module, a malfunctioning passenger-side inflator module, or a damaged SIR wiring harness.

1. Checks for an open circuit inside passenger-side inflator module.
2. Checks for an open circuit in low pressure sensor circuit.
3. Checks for an open circuit in low pressure sensor ground circuit
4. Checks for a short circuit between low pressure sensor circuit and battery power.

Fig 1: DTC 38 - Low Pressure Detected, Sensor Open Or Short To Ignition

Courtesy of GENERAL MOTORS CORP.